JP3568047B2 - Method of forming photovoltaic element - Google Patents

Description

振動劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を湿度５５％、温度２６℃の暗所に設置し、振動周波数６０Ｈｚで振幅０．１ｍｍの振動を５００時間加えた後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（振動劣化試験後の光電変換効率／初期光電変換効率）により行った。
【０１０５】
光劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を、湿度５５％、温度２６℃の環境に設置し、ＡＭ１．５（１００ｍＷ／ｃｍ^２）光を５００時間照射後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（光劣化試験後の光電変換効率／初期光電変換効率）により行った。測定の結果、（ＳＣ実１）に対して（ＳＣ比１）の光劣化後の光電変換効率の低下率及び振動劣化後の光電変換効率の低下率は以下のようになった。
【０１０６】

バイアス印加時の高温高湿度環境における振動劣化及び光劣化の測定を行った。予め初期光電変換効率を測定しておいた２つの太陽電池を湿度９２％、温度８６℃の暗所に設置し、順方向バイアス電圧として０．７２Ｖを印加した。一方の太陽電池には上記の振動を与えて、振動劣化を測定し、さらにもう一方の太陽電池にはＡＭ１．５の光を照射して、光劣化の測定を行った。測定の結果、（ＳＣ実１）に対して、（ＳＣ比１）の振動劣化後の光電変換効率の低下率及び光劣化後の光電変換効率の低下率は以下のようになった。
【０１０７】

光学顕微鏡を用いて層剥離の様子を観察した。（ＳＣ実１）では層剥離は見られなかったが、（ＳＣ比１）では層剥離が僅かに見られた。
以上のように本発明の太陽電池（ＳＣ実１）が、従来の太陽電池（ＳＣ比１）よりも太陽電池の光電変換効率における曲線因子、シリーズ抵抗、特性むら、光劣化特性、密着性、耐久性においてさらに優れた特性を有することが分かった。
【０１０８】
（実施例２）
図３に示す堆積装置を用いて図１のタンデム型太陽電池を作製した。
実施例１と同様な方法により準備された反射層２０１と反射増加層２０２が形成されている基坂４９０をロードチャンバー４０１内の基板搬送用レール４１３上に配置し、不図示の真空排気ポンプによりロードチャンバー４０１内を圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１０９】
次にあらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０２及び堆積チャンバー４１７内へゲートバルブ４０６を開けて搬送した。基板４９０の裏面を基板加熱用ヒーター４１０に密着させ加熱し、堆積チャンバー４１７内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１１０】
以上のようにして成膜の準備が完了した後、μｃ−ＳｉからなるＲＦｎ型層２０３を形成した。
μｃ−ＳｉからなるＲＦｎ型層を形成するには、Ｈ_２ガスを堆積チャンバー４１７内にガス導入管４２９を通して導入し、Ｈ_２ガス流量が３００ｓｃｃｍになるようにバルブ４４１、４３１、４３０を開け、マスフローコントローラー４３６で調整した。堆積チャンバー４１７内の圧力が１．１Ｔｏｒｒになるように不図示のコンダクタンスバルブで調整した。基板４９０の温度が３８０℃になるように基坂加熱用ヒーター４１０を設定し、基板温度が安定したところで、ＳｉＨ_４ガス、ＰＨ_３／Ｈ_２ガスを堆積チャンバー４１７内にバルブ４４３、４３３、４４４、４３４を操作してガス導入管４２９を通して導入した。この時、ＳｉＨ_４ガス流量が１．２ｓｃｃｍ、Ｈ_２ガス流量が９０ｓｃｃｍ、ＰＨ_３／Ｈ_２ガス流量が２００ｓｃｃｍとなるようにマスフローコントローラー４３８、４３６、４３９で調整し、堆積チャンバー４１７内の圧力は１．１Ｔｏｒｒとなるように調整した。ＲＦ電源４２２の電力を０．０６Ｗ／ｃｍ^３に設定し、プラズマ形成用カップ４２０にＲＦ電力を導入し、グロー放電を生起させ、基板上にＲＦｎ型層の形成を開始し、層厚２０ｎｍのＲＦｎ型層を形成したところでＲＦ電源を切って、グロー放電を止め、ＲＦｎ型層２０３の形成を終えた。堆積チャンバー４１７内へのＳｉＨ_４ガス、ＰＨ_３／Ｈ_２の流入を止め、４分間、堆積室内へＨ_２ガスを流し続けたのち、Ｈ_２の流入も止め、堆積室内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１１１】
次にａ−Ｓｉからなるｎ／ｉバッファー層２５１をＲＦＰＣＶＤ法によって形成した。まず、あらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０３及びｉ型層堆積チャンバー４１８内へゲートバルブ４０７を開けて基板４９０を搬送した。基板４９０の裏面を基板加熱用ヒーター４１１に密着させ加熱し、ｉ型層堆積チャンバー４１８内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１１２】
ｎ／ｉバッファー層２５１を作製するには、基板４９０の温度が３６０℃になるように基板加熱用ヒーター４１１を設定し、基板が十分加熱されたところでバルブ４６４、４５４、４５０、４６３、４５３を徐々に開いて、Ｓｉ_２Ｈ_６ガス、Ｈ_２ガスをガス導入管４４９を通じてｉ型層堆積チャンバー４１８内に流入させた。この時、Ｓｉ_２Ｈ_６ガス流量が２．５ｓｃｃｍ、Ｈ_２ガス流量が１００ｓｃｃｍとなるように各々のマスフローコントローラー４５９、４５８で調整した。ｉ型層堆積チャンバー４１８内の圧力は、０．８Ｔｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。次に、ＲＦ電源４２４を０．０８Ｗ／ｃｍ^３に設定し、バイアス棒４２８に印加し、グロー放電を生起させ、シャッター４２７を開けることでＲＦｎ型層上にｎ／ｉバッファー層の作製を開始し、層厚１０ｎｍのｎ／ｉバッファー層を作製したところでＲＦグロー放電を止め、ＲＦ電源４２４の出力を切り、ｎ／ｉバッファー層２５１の作製を終えた。バルブ４６４、４５４を閉じて、ｉ型層堆積チャンバー４１８内へのＳｉ_２Ｈ_６ガスの流入を止め、２分間ｉ型層堆積チャンバー４１８内へＨ_２ガスを流し続けたのち、バルブ４５３、４５０を閉じ、ｉ型層堆積チャンバー４１８内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１１３】
次にａ−ＳｉＧｅからなるＭＷｉ型層２０４をＭＷＰＣＶＤ法によって形成した。ＭＷｉ型層を作製するには、基板４９０の温度が３８０℃になるように基板加熱用ヒーター４１１を設定し、基板が十分加熱されたところでバルブ４６１、４５１、４５０、４６２、４５２、４６３、４５３を徐々に開いて、ＳｉＨ_４ガス、ＧｅＨ_４ガス、Ｈ_２ガスをガス導入管４４９を通じてｉ型層堆積チャンバー４１８内に流入させた。この時、ＳｉＨ_４ガス流量が４３ｓｃｃｍ、ＧｅＨ_４ガス流量が４２ｓｃｃｍ、Ｈ_２ガス流量が１８０ｓｃｃｍとなるように各々のマスフローコントローラー４５６、４５７、４５８で調整した。ｉ型層堆積チャンバー４１８内の圧力は、５ｍＴｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。次に、ＲＦ電源４２４を０．６０Ｗ／ｃｍ^３に設定し、バイアス棒４２８に印加した。その後、不図示のＭＷ電源の電力を０．２５Ｗ／ｃｍ^３に設定し、導波管４２６及びマイクロ波導入用窓４２５を通じてｉ型層堆積チャンバー４１８内にＭＷ電力導入し、グロー放電を生起させ、シャッター４２７を開けることでｎ／ｉバッファー層上にＭＷｉ型層の作製を開始し、層厚０．１５μｍのｉ型層を作製したところでＭＷグロー放電を止め、バイアス電源４２４の出力を切り、ＭＷｉ型層２０４の作製を終えた。バルブ４５１、４５２を閉じて、ｉ型層堆積チャンバー４１８内へのＳｉＨ_４ガス、ＧｅＨ_４ガスの流入を止め、２分間ｉ型層堆積チャンバー４１８内へＨ_２ガスを流し続けたのち、バルブ４５３、４５０を閉じ、ｉ型層堆積チャンバー４１８内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１１４】
次にａ−Ｓｉからなるｐ／ｉバッファー層２６１をＲＦＰＣＶＤ法によって形成した。ｐ／ｉバッファー層２６１を作製するには、基板４９０の温度が２５０℃になるように基板加熱用ヒーター４１１を設定し、基板が十分加熱されたところでバルブ４６４、４５４、４５０、４６３、４５３を徐々に開いて、Ｓｉ_２Ｈ_６ガス、Ｈ_２ガスをガス導入管４４９を通じてｉ型層堆積チャンバー４１８内に流入させた。この時、Ｓｉ_２Ｈ_６ガス流量が３ｓｃｃｍ、Ｈ_２ガス流量が７５ｓｃｃｍとなるように各々のマスフローコントローラー４５９、４５８で調整した。ｉ型層堆積チャンバー４１８内の圧力は、０．７Ｔｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。次に、ＲＦ電源４２４を０．０７Ｗ／ｃｍ^３に設定し、バイアス棒４２８に印加し、グロー放電を生起させ、シャッター４２７を開けることでＭＷｉ型層上にｐ／ｉバッファー層２６１の作製を開始し、層厚２０ｎｍのｐ／ｉバッファー層を作製したところでＲＦグロー放電を止め、ＲＦ電源４２４の出力を切り、ｐ／ｉバッファー層２６１の作製を終えた。バルブ４６４、４５４を閉じて、ｉ型層堆積チャンバー４１８内へのＳｉ_２Ｈ_６ガスの流入を止め、２分間ｉ型層堆積チャンバー４１８内へＨ_２ガスを流し続けたのち、バルブ４５３、４５０を閉じ、ｉ型層堆積チャンバー４１８内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１１５】
次にａ−ＳｉＣからなるＲＦｐ型層２０５を形成するには、あらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０４及びｐ型層堆積チャンバー４１９内へゲートバルブ４０８を開けて基板４９０を搬送した。基板４９０の裏面を基板加熱用ヒーター４１２に密着させ加熱し、ｐ型層堆積チャンバー４１９内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１１６】
基板４９０の温度が２５０℃になるように基板加熱用ヒーター４１２を設定し、基板温度が安定したところで、Ｈ_２ガス、ＳｉＨ_４／Ｈ_２ガス、ＢＦ_３／Ｈ_２（希釈度：１％）ガス，ＣＨ_４ガスを堆積チャンバー４１９内にバルブ４８１、４７１、４７０、４８２、４７２、４８３、４７３、４８４、４７４を操作してガス導入管４６９を通して導入した。この時、Ｈ_２ガス流量が６０ｓｃｍ、ＳｉＨ_４／Ｈ_２ガス流量が０．４ｓｃｃｍ、ＢＦ_３／Ｈ_２（希釈度：１％）ガス流量が１ｓｃｃｍ，ＣＨ_４ガス流量が０．３ｓｃｃｍとなるようにマスフローコントローラー４７６、４７７、４７８、４７９で調整し、堆積チャンバー４１９内の圧力は１．７Ｔｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。ＲＦ電源４２３の電力を０．０７Ｗ／ｃｍ^３に設定し、プラズマ形成用カップ４２１にＲＦ電力を導入し、グロー放電を生起させ、ｐ／ｉバッファー層上にＲＦｐ型層の形成を開始し、層厚１０ｎｍのＲＦｐ型層を形成したところでＲＦ電源を切って、グロー放電を止め、ＲＦｐ型層２０５の形成を終えた。バルブ４７２、４８２、４７３、４８３、４７４、４８４を閉じてｐ型層堆積チャンバー４１９内へのＳｉＨ_４／Ｈ_２ガス、ＢＦ_３／Ｈ_２ガス，ＣＨ_４ガスの流入を止め、３分間、ｐ型層堆積チャンバー４１９内へＨ_２ガスを流し続けたのち、バルブ４７１、４８１、４７０を閉じてＨ_２の流入も止め、ｐ型層堆積チャンバ４１９内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１１７】
次に本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表２（１）の条件で行った。本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行うには、第ＩＩＩ族元素含有ガスとしてＢＦ_３／Ｈ_２（希釈度：１％）ガス、シリコン原子含有ガスとしてＳｉ_２Ｈ_６ガス、Ｈ_２ガスを堆積チャンバー４１９内にガス導入管４６９を通して導入し、Ｈ_２ガス流量が１０００ｓｃｃｍになるようにバルブ４８１、４７１、４７０を開け、マスフローコントローラー４７６で調整した。第ＩＩＩ族元素含有ガスＢＦ_３ガスが全Ｈ_２ガス流量に対して０．４％になるようにバルブ４８３、４７３を開けマスフローコントローラー４７８で調整した。シリコン原子含有ガスは、Ｓｉ_２Ｈ_６が全Ｈ_２ガス流量に対して０．０３％になるように不図示のバルブを開け不図示のマスフローコントローラーで調整した。堆積チャンバー４１９内の圧力が０．０１３Ｔｏｒｒになるように不図示のコンダクタンスバルブで調整した。基板４９０の温度が２５０℃になるように基板加熱用ヒーター４１２を設定し、基板温度が安定したところで、不図示のＶＨＦ電源のＶＨＦ電力を０．０８Ｗ／ｃｍ^３に設定し、プラズマ形成用カップ４２１内にＶＨＦ電力を導入し、グロー放電を生起させ、４分間本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行った。その後ＶＨＦ電源を切って、グロー放電を止め、堆積チャンバー４１９内へのＢＦ_３／Ｈ_２、Ｓｉ_２Ｈ_６ガスの流入を止め、４分間、堆積チャンバー４１９内へＨ_２ガスを流し続けたのち、Ｈ_２ガスの流入も止め、堆積チャンバー４１９内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１１８】
次にμｃ−ＳｉからなるＲＦｎ型層２０６を形成するために、あらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０３を通って搬送チャンバー４０２及び堆積チャンバー４１７内へゲートバルブ４０８、４０７を開けて搬送した。基板４９０の裏面を基板加熱用ヒーター４１０に密着させ加熱し、堆積チャンバー４１７内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１１９】
μｃ−ＳｉからなるＲＦｎ型層を形成するには、Ｈ_２ガスを堆積チャンバー
４１７内にガス導入管４２９を通して導入し、Ｈ_２ガス流量が２００ｓｃｃｍになるようにバルブ４４１、４３１、４３０を開け、マスフローコントローラー４３６で調整した。堆積チャンバー４１７内の圧力が１．１Ｔｏｒｒになるように不図示のコンダクタンスバルブで調整した。基板４９０の温度が２５０℃になるように基板加熱用ヒーター４１０を設定し、基板温度が安定したところで、ＳｉＨ_４ガス、ＰＨ_３／Ｈ_２ガスを堆積チャンバー４１７内にバルブ４４３、４３３、４４４、４３４を操作してガス導入管４２９を通して導入した。この時、ＳｉＨ_４ガス流量が１．５ｓｃｃｍ、Ｈ_２ガス流量が８０ｓｃｃｍ、ＰＨ_３／Ｈ_２ガス流量が２５０ｓｃｃｍとなるようにマスフローコントローラー４３８、４３６、４３９で調整し、堆積チャンバー４１７内の圧力は１．１Ｔｏｒｒとなるように調整した。ＲＦ電源４２２の電力を０．０４Ｗ／ｃｍ^３に設定し、プラズマ形成用カップ４２０にＲＦ電力を導入し、グロー放電を生起させ、ＲＦｐ型層上にＲＦｎ型層の形成を開始し、層厚１０ｎｍのＲＦｎ型層を形成したところでＲＦ電源を切って、グロー放電を止め、ＲＦｎ型層２０６の形成を終えた。堆積チャンバー４１７内へのＳｉＨ_４ガス、ＰＨ_３／Ｈ_２の流入を止め、２分間、堆積室内へＨ_２ガスを流し続けたのち、Ｈ_２の流入も止め、堆積室内およびガス配管内を１×１０^{− ５}Ｔｏｒｒまで真空排気した。
【０１２０】
次にａ−ＳｉＣからなるｎ／ｉバッファー層２５２をＲＦＰＣＶＤ法によって形成した。まず、あらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０３及びｉ型層堆積チャンバー４１８内へゲートバルブ４０７を開けて基板４９０を搬送した。基板４９０の裏面を基板加熱用ヒーター４１１に密着させ加熱し、ｉ型層堆積チャンバー４１８内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１２１】
ｎ／ｉバッファー層２５２を作製するには、基板４９０の温度が２５０℃になるように基板加熱用ヒーター４１１を設定し、基板が十分加熱されたところでバルブ４６４、４５４、４５０、４６３、４５３、４６５、４５５を徐々に開いて、Ｓｉ_２Ｈ_６ガス、Ｈ_２ガス、ＣＨ_４ガスをガス導入管４４９を通じてｉ型層堆積チャンバー４１８内に流入させた。この時、Ｓｉ_２Ｈ_６ガス流量が０．４ｓｃｃｍ、Ｈ_２ガス流量が９０ｓｃｃｍ、ＣＨ_４ガス流量が０．２ｓｃｃｍとなるように各々のマスフローコントローラー４５９、４５８、４６０で調整した。
【０１２２】
ｉ型層堆積チャンバー４１８内の圧力は、１．０Ｔｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。次に、ＲＦ電源４２４を０．０６Ｗ／ｃｍ^３に設定し、バイアス棒４２８に印加し、グロー放電を生起させ、シャッター４２７を開けることでＲＦｎ型層上にｎ／ｉバッファー層の作製を開始し、層厚１０ｎｍのｎ／ｉバッファー層を作製したところでＲＦグロー放電を止め、ＲＦ電源４２４の出力を切り、ｎ／ｉバッファー層２５２の作製を終えた。バルブ４６４、４５４、４６５、４５５を閉じて、ｉ型層堆積チャンバー４１８内へのＳｉ_２Ｈ_６ガス、ＣＨ_４ガスの流入を止め、２分間ｉ型層堆積チャンバー４１８内ヘＨ_２ガスを流し続けたのち、バルブ４５３、４５０を閉じ、ｉ型層堆積チャンバー４１８内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１２３】
次にａ−ＳｉからなるＲＦｉ型層２０７をＲＦＰＣＶＤ法によって形成した。ＲＦｉ型層を作製するには、基板４９０の温度が２００℃になるように基板加熱用ヒーター４１１を設定し、基板が十分加熱されたところでバルブ４６４、４５４、４５０、４６３、４５３を徐々に開いて、Ｓｉ_２Ｈ_６ガス、Ｈ_２ガスをガス導入管４４９を通じてｉ型層堆積チャンバー４１８内に流入させた。この時、Ｓｉ_２Ｈ_６ガス流量が２ｓｃｃｍ、Ｈ_２ガス流量が８５ｓｃｃｍとなるように各々のマスフローコントローラー４５９、４５８で調整した。ｉ型層堆積チャンバー４１８内の圧力は、０．５Ｔｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。次に、ＲＦ電源４２４を０．０７Ｗ／ｃｍ^３に設定し、バイアス棒４２８に印加し、グロー放電を生起させ、シャッター４２７を開けることでｎ／ｉバッファー層２５２上にＲＦｉ型層の作製を開始し、層厚１１０ｎｍのｉ型層を作製したところでＲＦグロー放電を止め、ＲＦ電源４２４の出力を切り、ＲＦｉ型層２０７の作製を終えた。バルブ４６４、４５４を閉じて、ｉ型層堆積チャンバー４１８内へのＳｉ_２Ｈ_６ガスの流入を止め、２分間ｉ型層堆積チャンバー４１８内へＨ_２ガスを流し続けたのち、バルブ４５３、４５０を閉じ、ｉ型層堆積チャンバー４１８内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
次にａ−Ｓｉｃからなるｐ／ｉバッファー層２６２をＲＦＰＣＶＤ法によって形成した。ｐ／ｉバッファー層２６２を作製するには、基板４９０の温度が２００℃になるように基板加熱用ヒーター４１１を設定し、基板が十分加熱されたところでバルブ４６４、４５４、４５０、４６３、４５３、４６５、４５５を徐々に開いて、Ｓｉ_２Ｈ_６ガス、Ｈ_２ガス、ＣＨ_４ガスをガス導入管４４９を通じてｉ型層堆積チャンバー４１８内に流入させた。この時、Ｓｉ_２Ｈ_６ガス流量が０．４ｓｃｃｍ、Ｈ_２ガス流量が６５ｓｃｃｍ、ＣＨ_４ガス流量が０．３ｓｃｃｍとなるように各々のマスフローコントローラー４５９、４５８、４６０で調整した。ｉ型層堆積チャンバー４１８内の圧力は、１．１Ｔｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。次に、ＲＦ電源４２４を０．０６Ｗ／ｃｍ^３に設定し、バイアス棒４２８に印加し、グロー放電を生起させ、シャッター４２７を開けることでＲＦｉ型層上にｐ／ｉバッファー層の作製を開始し、層厚１５ｎｍのｐ／ｉバッファー層を作製したところでＲＦグロー放電を止め、ＲＦ電源４２４の出力を切り、ｐ／ｉバッファー層２６２の作製を終えた。バルブ４６４、４５４、４６５、４５５を閉じて、ｉ型層堆積チャンバー４１８内へのＳｉ_２Ｈ_６ガス、ＣＨ_４ガスの流入を止め、２分間ｉ型層堆積チャンバー４１８内へＨ_２ガスを流し続けたのち、バルブ４５３、４５０を閉じ、ｉ型層堆積チャンバー４１８内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１２４】
次にａ−ＳｉＣからなるＲＦｐ型層２０８を形成するには、あらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０４及びｐ型層堆積チャンバー４１９内へゲートバルブ４０８を開けて基板４９０を搬送した。基板４９０の裏面を基板加熱用ヒーター４１２に密着させ加熱し、ｐ型層堆積チャンバー４１９内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１２５】
基板４９０の温度が１７０℃になるように基板加熱用ヒーター４１２を設定し、基板温度が安定したところで、Ｈ_２ガス、ＳｉＨ_４／Ｈ_２ガス、ＢＦ_３／Ｈ_２（希釈度：１％）ガス，ＣＨ_４ガスを堆積チャンバー４１９内にバルブ４８１、４７１、４７０、４８２、４７２、４８３、４７３、４８４、４７４を操作してガス導入管４６９を通して導入した。この時、Ｈ_２ガス流量が７０ｓｃｍ、ＳｉＨ_４／Ｈ_２ガス流量が０．４ｓｃｃｍ、ＢＦ_３／Ｈ_２（希釈度：１％）ガス流量が１ｓｃｃｍ，ＣＨ_４ガス流量が０．３ｓｃｃｍとなるようにマスフローコントローラー４７６、４７７、４７８、４７９で調整し、堆積チャンバー４１９内の圧力は１．７Ｔｏｒｒとなるように不図示のコンダクタンスバルブの開口を調整した。ＲＦ電源４２３の電力を０．０７Ｗ／ｃｍ^３に設定し、プラズマ形成用カップ４２１にＲＦ電力を導入し、グロー放電を生起させ、ｐ／ｉバッファー層２６２上にＲＦｐ型層の形成を開始し、層厚１０ｎｍのＲＦｐ型層を形成したところでＲＦ電源を切って、グロー放電を止め、ＲＦｐ型層２０８の形成を終えた。バルブ４７２、４８２、４７３、４８３、４７４、４８４を閉じてｐ型層堆積チャンバー４１９内へのＳｉＨ_４／Ｈ_２ガス、ＢＦ_３／Ｈ_２ガス，ＣＨ_４ガスの流入を止め、２分間、ｐ型層堆積チャンバー４１９内へＨ_２ガスを流し続けたのち、バルブ４７１、４８１、４７０を閉じてＨ_２の流入も止め、ｐ型層堆積チャンバー４１９内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１２６】
次にあらかじめ不図示の真空排気ポンプにより真空引きしておいたアンロードチャンバー４０５内へゲートバルブ４０９を開けて基板４９０を搬送し不図示のリークバルブを開けて、アンロードチャンバー４０５をリークした。
次に、ＲＦｐ型層２０８上に、透明導電層２１２として、層厚７０ｎｍのＩＴＯを真空蒸着法で真空蒸着した。
【０１２７】
次に透明導電層２１２上に櫛型の穴が開いたマスクを乗せ、Ｃｒ（４０ｎｍ）／Ａｇ（１０００ｎｍ）／Ｃｒ（４０ｎｍ）からなる櫛形の集電電極２１３を真空蒸着法で真空蒸着した。
以上で太陽電池の作製を終えた。この太陽電池を（ＳＣ実２）と呼ぶことにし、本発明の微量第ＩＩＩ族元素含有水素プラズマ処理条件、ＲＦｎ型層、ｎ／ｉバッファー層、ＭＷｉ型層、ｐ／ｉバッファー層、ＲＦｉ型層、ＲＦｐ型層の形成条件を表２（１）〜２（２）に示す。
【０１２８】
＜比較例２＞
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行わず、他は実施例２と同じ条件で太陽電池（ＳＣ比２）を作製した。
太陽電池（ＳＣ実２）及び（ＳＣ比２）はそれぞれ９個づつ作製し、初期光電変換効率（光起電力／入射光電力）、振動劣化、光劣化、及びバイアス電圧印加時の高温高湿環境における振動劣化、光劣化の測定を行なった。
【０１２９】
初期光電変換効率は、作製した太陽電池を、ＡＭ１．５（１００ｍＷ／ｃｍ^２）光照射下に設置して、Ｖ−Ｉ特性を測定することにより得られる。測定の結果、（ＳＣ比２）に対して、（ＳＣ実２）の初期光電変換効率の曲線因子（Ｆ．Ｆ．）、シリーズ抵抗（Ｒｓ）及び特性むらは以下のようになった。

振動劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を湿度５５％、温度２８℃の暗所に設置し、振動周波数６０Ｈｚで振幅０．１ｍｍの振動を５５０時間加えた後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（振動劣化試験後の光電変換効率／初期光電変換効率）により行った。
【０１３０】
光劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を、湿度５５％、温度２８℃の環境に設置し、ＡＭ１．５（１００ｍＷ／ｃｍ^２）光を５００時間照射後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（光劣化試験後の光電変換効率／初期光電変換効率）により行った。測定の結果、（ＳＣ実２）に対して（ＳＣ比２）の光劣化後の光電変換効率の低下率及び振動劣化後の光電変換効率の低下率は以下のようになった。
【０１３１】

バイアス印加時の高温高湿度環境における振動劣化及び光劣化の測定を行った。予め初期光電変換効率を測定しておいた２つの太陽電池を湿度９０％、温度８２℃の暗所に設置し、順方向バイアス電圧として０．７１Ｖを印加した。一方の太陽電池には上記の振動を与えて、振動劣化を測定し、さらにもう一方の太陽電池にはＡＭ１．５の光を照射して、光劣化の測定を行った。測定の結果、（ＳＣ実２）に対して、（ＳＣ比２）の振動劣化後の光電変換効率の低下率及び光劣化後の光電変換効率の低下率は以下のようになった。
【０１３２】

光学顕微鏡を用いて層剥離の様子を観察した。（ＳＣ実２）では層剥離は見られなかったが、（ＳＣ比２）では層剥離が僅かに見られた。
以上のように本発明の太陽電池（ＳＣ実２）が、従来の太陽電池（ＳＣ比２）よりも太陽電池の光電変換効率における曲線因子、シリーズ抵抗、特性むら、光劣化特性、密着性、耐久性においてさらに優れた特性を有することが分かった。
【０１３３】
（実施例３）
図３に示す堆積装置を用いて図２のトリプル型太陽電池を作製した。
実施例１と同様の方法により準備された反射層３０１と反射増加層３０２が形成されている基坂４９０をロードチャンバー４０１内の基板搬送用レール４１３上に配置し、不図示の真空排気ポンプによりロードチャンバー４０１内を圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１３４】
次にあらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０２及び堆積チャンバー４１７内へゲートバルブ４０６を開けて搬送した。基板４９０の裏面を基板加熱用ヒーター４１０に密着させ加熱し、堆積チャンバー４１７内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１３５】
以上のようにして成膜の準備が完了した後、実施例１と同様な方法によりμｃ−ＳｉからなるＲＦｎ型層３０３を形成した。
次にあらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０３及び堆積チャンバー４１８内へゲートバルブ４０７を開けて搬送した。基板４９０の裏面を基板加熱用ヒーター４１１に密着させ加熱し、堆積チャンバー４１８内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１３６】
次に、実施例１と同様な方法によりａ−Ｓｉからなるｎ／ｉバッファー層３５１、ａ−ＳｉＧｅからなるＭＷｉ型層３０４、ａ−Ｓｉからなるｐ／ｉバッファー層３６１，ａ−ＳｉＣからなるＲＦｐ型層３０５をＲＦＰＣＶＤ法及びＭＷＰＣＶＤ法により順次形成した。
次に、本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行うために、実施例１と同様な方法により、基板４９０を堆積チャンバー４１８内に搬送した。
【０１３７】
次に本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表３（１）の条件で行った。本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行うには、第ＩＩＩ族元素含有ガスとしてＢ_２Ｈ_６／Ｈ_２（希釈度：１０％）ガス、シリコン原子含有ガスとしてＳｉＣｌ_２Ｈ_２／Ｈｅ（希釈度：１０００ｐｐｍ）ガス、Ｈ_２ガスを堆積チャンバー４１８内にガス導入管４４９を通して導入し、Ｈ_２ガス流量１０００ｓｃｃｍになるようにバルブ４６３、４５３、４５０を開け、マスフローコントローラー４５８で調整した。第ＩＩＩ族元素含有ガスＢ_２Ｈ_６／Ｈ_２（希釈度：１０％）ガスが全Ｈ_２ガス流量に対して２．２％になるようにバルブ４６８、４６６を開けマスフローコントローラー４６７で調整した。シリコン原子含有ガスは、ＳｉＣｌ_２Ｈ_２／Ｈｅ（希釈度：１０００ｐｐｍ）が全Ｈ_２ガス流量に対してＳｉＣｌ_２Ｈ_２ガスの割合が０．０４％になるように不図示のバルブを開け不図示のマスフローコントローラーで調整した。堆積チャンバー４１８内の圧力が０．００８Ｔｏｒｒになるように不図示のコンダクタンスバルブで調整した。基板４９０の温度が３００℃になるように基板加熱用ヒーター４１１を設定し、基板温度が安定したところで、不図示のＭＷ電源の電力を０．１５Ｗ／ｃｍ^３に設定し、導波管４２６及びマイクロ波導入用窓４２５を通じてｉ型層堆積チャンバー４１８内にＭＷ電力導入し、グロー放電を生起させ、シャッター４２７を開けることで、４分間本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行った。その後ＭＷ電源を切って、グロー放電を止め、堆積チャンバー４１８内へのＢ_２Ｈ_６／Ｈ_２（希釈度１０％）ガス、ＳｉＣｌ_２Ｈ_２／Ｈｅ（希釈度：１０００ｐｐｍ）ガスの流入を止め、４分間、堆積チャンバー４１８内へＨ_２ガスを流し続けたのち、Ｈ_２ガスの流入も止め、堆積チャンバー４１８内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１３８】
次に実施例１と同様な方法により、μｃ−ＳｉからなるＲＦｎ型層３０６、ａ−Ｓｉからなるｎ／ｉバッファー層３５２、ａ−ＳｉＧｅからなるＭＷｉ型層３０７、ａ−Ｓｉからなるｐ／ｉバッファー層３６２、ａ−ＳｉＣからなるＲＦｐ型層３０８をＲＦＰＣＶＤ法及びＭＷＰＣＶＤ法により順次形成した。
次に本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表３（２）の条件で行った。本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行うには、第ＩＩＩ族元素含有ガスとしてＢ_２Ｈ_６／Ｈ_２（希釈度：１０％）ガス、シリコン原子含有ガスとしてＳｉＨ_４ガス、Ｈ_２ガスを堆積チャンバー４１７内にガス導入管４２９を通して導入し、Ｈ_２ガス流量が１３００ｓｃｃｍになるようにバルブ４４１、４３１、４３０を開け、マスフローコントローラー４３６で調整した。第ＩＩＩ族元素含有ガスＢ_２Ｈ_６ガスが全Ｈ_２ガス流量に対して１．３％になるように不図示のバルブを開け不図示のマスフローコントローラーで調整した。シリコン原子含有ガスは、ＳｉＨ_４ガスが全Ｈ_２ガス流量に対して０．０４％になるようにバルブ４４３、４３３を開けマスフローコントローラー４３８で調整した。堆積チャンバー４１７内の圧力が０．７Ｔｏｒｒになるように不図示のコンダクタンスバルブで調整した。基板４９０の温度が２５０℃になるように基板加熱用ヒーター４１０を設定し、基板温度が安定したところで、ＲＦ電源４２４の電力を０．０３Ｗ／ｃｍ^３に設定し、プラズマ形成用カップ４２０内にＲＦ電力を導入し、グロー放電を生起させ、３分間本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行った。その後ＲＦ電源を切って、グロー放電を止め、堆積チャンバー４１７内へのＢ_２Ｈ_６／Ｈ_２（希釈度：１０％）ガス、ＳｉＨ_４ガスの流入を止め、３分間、堆積チャンバー４１７内へＨ_２ガスを流し続けたのち、Ｈ_２ガスの流入も止め、堆積チャンバー４１７内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１３９】
次に実施例１と同様な方法により、μｃ−ＳｉからなるＲＦｎ型層３０９、ａ−ＳｉＣからなるｎ／ｉバッファー層３５３、ａ−ＳｉからなるＲＦｉ型層３１０、ａ−ＳｉＣからなるｐ／ｉバッファー層３６３、ａ−ＳｉＣからなるＲＦｐ型層３１１をＲＦＰＣＶＤ法により順次形成した。
次に、ＲＦｐ型層３１１上に、透明導電層３１２として、層厚７０ｎｍのＩＴＯを真空蒸着法で真空蒸着した。
【０１４０】
次に透明導電層３１２上に櫛型の穴が開いたマスクを乗せ、Ｃｒ（４０ｎｍ）／Ａｇ（１０００ｎｍ）／Ｃｒ（４０ｎｍ）からなる櫛形の集電電極３１３を真空蒸着法で真空蒸着した。
以上で太陽電池の作製を終えた。この太陽電池を（ＳＣ実３）と呼ぶことにし、本発明の微量第ＩＩＩ族元素含有水素プラズマ処理条件、ＲＦｎ型層、ｎ／ｉバッファー層、ＭＷｉ型層、ｐ／ｉバッファー層、ＲＦｉ型層、ＲＦｐ型層の形成条件を表３（１）〜３（３）に示す。
【０１４１】
＜比較例３＞
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を行わず、他は実施例３と同じ条件で太陽電池（ＳＣ比３）を作製した。
太陽電池（ＳＣ実３）及び（ＳＣ比３）はそれぞれ７個づつ作製し、初期光電変換効率（光起電力／入射光電力）、振動劣化、光劣化、バイアス電圧印加時の高温高湿環境における振動劣化、光劣化、及び逆方向バイアス電圧印加特性の測定を行なった。
【０１４２】
初期光電変換効率は、作製した太陽電池を、ＡＭ１．５（１００ｍＷ／ｃｍ^２）光照射下に設置して、Ｖ−Ｉ特性を測定することにより得られる。測定の結果、（ＳＣ比３）に対して、（ＳＣ実３）の初期光電変換効率の曲線因子（ＦＦ）、シリーズ抵抗（Ｒｓ）及び特性むらは以下のようになった。

振動劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を湿度５５％、温度２７℃の暗所に設置し、振動周波数６０Ｈｚで振幅０．１ｍｍの振動を５５０時間加えた後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（振動劣化試験後の光電変換効率／初期光電変換効率）により行った。
【０１４３】
光劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を、湿度５５％、温度２７℃の環境に設置し、ＡＭ１．５（１００ｍＷ／ｃｍ^２）光を５５０時間照射後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（光劣化試験後の光電変換効率／初期光電変換効率）により行った。測定の結果、（ＳＣ実３）に対して（ＳＣ比３）の光劣化後の光電変換効率の低下率及び振動劣化後の光電変換効率の低下率は以下のようになった。
【０１４４】

バイアス印加時の高温高湿度環境における振動劣化及び光劣化の測定を行った。予め初期光電変換効率を測定しておいた２つの太陽電池を湿度９０％温度８０℃の暗所に設置し、順方向バイアス電圧として０．７１Ｖを印加した。一方の太陽電池には上記の振動を与えて、振動劣化を測定し、さらにもう一方の太陽電池にはＡＭ１．５の光を照射して、光劣化の測定を行った。
【０１４５】
測定の結果、（ＳＣ実３）に対して、（ＳＣ比３）の振動劣化後の光電変換効率の低下率及び光劣化後の光電変換効率の低下率は以下のようになった。

逆方向バイアス電圧印加特性の測定は、予め初期光電変換効率を測定しておいた太陽電池を湿度５３％、温度８０℃の暗所に設置し、逆方向バイアス電圧を５．０Ｖ、１００時間印加した後、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率を測定し、その低下率（逆方向バイアス電圧印加後の光電変換効率／初期光電変換効率）により行った。
【０１４６】
測定の結果、（ＳＣ実３）に対して、（ＳＣ比３）の逆方向バイアス電圧印加後の低下率は以下のようなった。
（ＳＣ比３） ０．８５倍
光学顕微鏡を用いて層剥離の様子を観察した。（ＳＣ実３）では層剥離は見られなかったが、（ＳＣ比３）では層剥離が僅かに見られた。
【０１４７】
以上のように本発明の太陽電池（ＳＣ実３）が、従来の太陽電池（ＳＣ比３）よりも太陽電池の光電変換効率における曲線因子、シリーズ抵抗、特性むら、光劣化特性、密着性、耐久性、逆方向バイアス電圧印加特性においてさらに優れた特性を有することが分かった。
（実施例４）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表４（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表４（１）に、トリプル型太陽電池の作製条件を表４（２）に示す。
【０１４８】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表４（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の水素流量は、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において１〜２０００ｓｃｃｍが適した流量であることが分かった。
【０１４９】
（実施例５）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表５（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表５（１）に、トリプル型太陽電池の作製条件を表５（２）に示す。
【０１５０】
実施例３と同様に、作製したトリプル型太陽電池の表価を行った。その結果を表５（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の投入電力を実施例４のＲＦ電源からＶＨＦ電源に変えても、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において水素流量は、１〜２０００ｓｃｃｍが適した流量であることが分かった。
【０１５１】
（実施例６）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表６（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表６（１）に、トリプル型太陽電池の作製条件を表６（２）に示す。
【０１５２】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表６（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の、水素ガスに添加される第ＩＩＩ族元素含有ガスの添加量は、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において、０．０５％から３％が好ましい範囲であることが分かった。
【０１５３】
（実施例７）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表７（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。徴量第ＩＩＩ族元素含有水素プラズマ処理条件を表７（１）に、卜リプル型太陽電池の作製条件を表７（２）に示す。
【０１５４】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表７（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の水素ガスに添加される第ＩＩＩ族元素含有ガスの添加量は、投入電力を実施例６のＲＦ電源からＶＨＦ電源に変えても、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ低抗特性、耐久性、逆方向バイアス電圧印加特性において０．０５％から３％が好ましい範囲であることが分かった。
【０１５５】
（実施例８）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表８（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表８（１）に、トリプル型太陽電池の作製条件を表８（２）に示す。
【０１５６】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表８（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の水素ガスに添加される第ＩＩＩ族元素含有ガスの添加量は、投入電力を実施例６のＲＦ電源からＭＷ電源に変えても、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．０５％から３％が好ましい範囲であることが分かった。
【０１５７】
（実施例９）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表９（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表９（１）に、トリプル型太陽電池の作製条件を表９（２）に示す。
【０１５８】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表９（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の、水素ガスに添加されるシリコン原子含有ガスの添加量は、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において、０．００１％から０．１％が好ましい範囲であることが分かった。
【０１５９】
（実施例１０）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１０（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１０（１）に、トリプル型太陽電池の作製条件を表１０（２）に示す。
【０１６０】
実施例３と同様に、作製した卜リプル型太陽電池の評価を行った。その結果を表１０（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の水素ガスに添加されるシリコン原子含有ガスの添加量は、投入電力を実施例９のＲＦ電源からＶＨＦ電源に変えても、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．００１％から０．１％が好ましい範囲であることが分かった。
【０１６１】
（実施例１１）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１１（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１１（１）に、卜リプル型太陽電池の作製条件を表１１（２）に示す。
【０１６２】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１１（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の水素ガスに添加されるシリコン原子含有ガスの添加量は、投入電力を実施例９のＲＦ電源からＭＷ電源に変えても、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．００１％から０．１％が好ましい範囲であることが分かった。
【０１６３】
（実施例１２）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１２（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１２（１）に、トリプル型太陽電池の作製条件を表１２（２）に示す。
【０１６４】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１２（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の圧力は、投入電力にＲＦ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．０５Ｔｏｒｒから１０Ｔｏｒｒが好ましい範囲であることが分かった。
【０１６５】
（実施例１３）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１３（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１３（１）に、トリプル型太陽電池の作製条件を表１３（２）に示す。
【０１６６】
実施例３と同様に、作製した卜リプル型太陽電池の評価を行った。その結果を表１３（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の圧力は、投入電力にＶＨＦ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．０００１Ｔｏｒｒから１Ｔｏｒｒが好ましい範囲であることが分かった。
【０１６７】
（実施例１４）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１４（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１４（１）に、トリプル型太陽電池の作製条件を表１４（２）に示す。
【０１６８】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１４（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の圧力は、投入電力にＭＷ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．０００１Ｔｏｒｒから０．０１Ｔｏｒｒが好ましい範囲であることが分かった。
【０１６９】
（実施例１５）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１５（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１５（１）に、トリプル型太陽電池の作製条件を表１５（２）に示す。
【０１７０】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１５（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の投入パワー密度（電力量）は、投入電力にＲＦ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．０１Ｗ／ｃｍ^３から１．０Ｗ／ｃｍ^３が好ましい範囲であることが分かった。
【０１７１】
（実施例１６）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１６（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１６（１）に、トリプル型太陽電池の作製条件を表１６（２）に示す。
【０１７２】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１６（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の投入パワー密度（電力量）は、投入電力にＶＨＦ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において０．０１Ｗ／ｃｍ^３から１．０Ｗ／ｃｍ^３が好ましい範囲であることが分かった。
【０１７３】
（実施例１７）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１７（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１７（１）に、トリプル型太陽電池の作製条件を表１７（２）に示す。
【０１７４】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１７（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の投入パワー密度（電力量）は、投入電力にＭＷ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性において０．１Ｗ／ｃｍ^３から１０Ｗ／ｃｍ^３が好ましい範囲であることが分かった。
【０１７５】
（実施例１８）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１８（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１８（１）に、トリプル型太陽電池の作製条件を表１８（２）に示す。
【０１７６】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１８（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の基板温度は、投入電力にＲＦ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において１００℃から４００℃が好ましい範囲であることが分かった。
【０１７７】
（実施例１９）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表１９（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表１９（１）に、トリプル型太陽電池の作製条件を表１９（２）に示す。
【０１７８】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表１９（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の基板温度は、投入電力にＶＨＦ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性において５０℃から３００℃が好ましい範囲であることが分かった。
【０１７９】
（実施例２０）
実施例３と同様に図３に示す堆積装置を用いて本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表２０（１）の条件において２回行い、実施例３と同様に図２のトリプル型太陽電池を作製した。微量第ＩＩＩ族元素含有水素プラズマ処理条件を表２０（１）に、トリプル型太陽電池の作製条件を表２０（２）に示す。
【０１８０】
実施例３と同様に、作製したトリプル型太陽電池の評価を行った。その結果を表２０（３）に示す。
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理の基板温度は、投入電力にＭＷ電源を使用した場合、太陽電池の光電変換効率における曲線因子、特性むら、光劣化特性、シリ−ズ抵抗特性、耐久性において５０℃から３００℃が好ましい範囲であることが分かった。
【０１８１】
（実施例２１）
図３に示す堆積装置を用いて図２のトリプル型太陽電池を作製した。
実施例１と同様の方法により準備された反射層３０１と反射増加層３０２が形成されている基板４９０をロードチャンバー４０１内の基板搬送用レール４１３上に配置し、不図示の真空排気ポンプによりロードチャンバー４０１内を圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１８２】
次にあらかじめ不図示の真空排気ポンプにより真空引きしておいた搬送チャンバー４０２及び堆積チャンバー４１７内へゲートバルブ４０６を開けて搬送した。基板４９０の裏面を基板加熱用ヒーター４１０に密着させ加熱し、堆積チャンバー４１７内を不図示の真空排気ポンプにより圧力が約１×１０^−５Ｔｏｒｒになるまで真空排気した。
【０１８３】
次に微量シラン系ガス含有水素プラズマ処理を表２１（１）の条件で行った。微量シラン系ガス含有水素プラズマ処理を行うには、シリコン原子含有ガスとしてＳｉＨ_４／Ｈ_２（希釈度：１０００ｐｐｍ）ガス、Ｈ_２ガスを堆積チャンバー４１７内にガス導入管４２９を通して導入し、Ｈ_２ガス流量が１１５０ｓｃｃｍになるようにバルブ４４１、４３１、４３０を開け、マスフローコントローラー４３６で調整した。シリコン原子含有ガスは、全Ｈ_２ガス流量に対してＳｉＨ_４ガスの割合が０．０３％になるようにバルブ４４２、４３２を開けマスフローコントローラー４３７で調整した。堆積チャンバー４１７内の圧力が０．８Ｔｏｒｒになるように不図示のコンダクタンスバルブで調整した。基板４９０の温度が３６０℃になるように基板加熱用ヒーター４１０を設定し、基板温度が安定したところで、ＲＦ電源４２２の電力を０．０４Ｗ／ｃｍ^３に設定し、ＲＦ電力を導入し、プラズマ形成用カップ４２０内にグロー放電を生起させ、３分間微量シラン系ガス含有水素プラズマ処理を行った。その後ＲＦ電源を切って、グロー放電を止め、堆積チャンバー４１７内へのＳｉＨ_４／Ｈ_２（希釈度：１０００ｐｐｍ）ガスの流入を止め、５分間、堆積チャンバー４１７内へＨ_２ガスを流し続けたのち、Ｈ_２ガスの流入も止め、堆積チャンバー４１７内およびガス配管内を１×１０^−５Ｔｏｒｒまで真空排気した。
【０１８４】
以上のようにして成膜の準備が完了した後、実施例２と同様な方法によりμｃ−ＳｉからなるＲＦｎ型層３０３を形成した。
次に微量シラン系ガス含有水素プラズマ処理を表２１（２）の条件で行った。次に実施例２と同様な方法によりａ−ＳｉＣからなるｎ／ｉバッファー層３５１をＲＦＰＣＶＤ法によって形成した。
【０１８５】
次に微量シラン系ガス含有水素プラズマ処理を表２１（３）の条件で行った。次に実施例２と同様な方法によりａ−ＳｉＧｅからなるＭＷｉ型層３０４をＭＷＰＣＶＤ法により形成した。
次に微量シラン系ガス含有水素プラズマ処理を表２１（４）の条件で行った。次に実施例２と同様な方法によりａ−ＳｉＣからなるｐ／ｉバッファー層３６１をＲＦＰＣＶＤ法によって形成した。
【０１８６】
次に微量シラン系ガス含有水素プラズマ処理を表２１（５）の条件で行った。次に実施例２と同様な方法によりａ−ＳｉＣからなるＲＦｐ型層３０５をＲＦＰＣＶＤ法によって形成した。
次に本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表２１（６）の条件で行った。
【０１８７】
次に実施例２と同様な方法によりμｃ−ＳｉからなるＲＦｎ型層３０６をＲＦＰＣＶＤ法によって形成した。
次に微量シラン系ガス含有水素プラズマ処理を表２１（７）の条件で行った。次に実施例２と同様な方法によりａ−ＳｉＣからなるｎ／ｉバッファー層３５２をＲＦＰＣＶＤ法によって形成した。
【０１８８】
次に微量シラン系ガス含有水素プラズマ処理を表２１（８）の条件で行った。次に実施例２と同様な方法によりａ−ＳｉＧｅからなるＭＷｉ型層３０７をＭＷＰＣＶＤ法により形成した。
次に微量シラン系ガス含有水素プラズマ処理を表２１（９）の条件で行った。次に実施例２と同様な方法によりａ−ＳｉＣからなるｐ／ｉバッファー層３６２をＲＦＰＣＶＤ法によって形成した。
【０１８９】
次に微量シラン系ガス含有水素プラズマ処理を表２１（１０）の条件で行った。 次に実施例２と同様な方法により、ａ−ＳｉＣからなるＲＦｐ型層３０８を形成した。
次に本発明の微量第ＩＩＩ族元素含有水素プラズマ処理を表２１（１１）の条件で行った。
【０１９０】
次に実施例２と同様な方法により、μｃ−ＳｉからなるＲＦｎ型層３０９を形成した。
次に微量シラン系ガス含有水素プラズマ処理を表２１（１２）の条件で行った。 次に実施例２と同様な方法によりａ−ＳｉＣからなるｎ／ｉバッファー層３５３をＲＦＰＣＶＤ法によって形成した。
【０１９１】
次に微量シラン系ガス含有水素プラズマ処理を表２１（１３）の条件で行った。 次に実施例２と同様な方法によりａ−ＳｉからなるＲＦｉ型層３１０をＲＦＰＣＶＤ法によって形成した。
次に微量シラン系ガス含有水素プラズマ処理表２１（１４）の条件でを行った。 次に実施例２と同様な方法によりａ−ＳｉＣからなるｐ／ｉバッファー層３６３をＲＦＰＣＶＤ法によって形成した。
【０１９２】
次に微量シラン系ガス含有水素プラズマ処理を表２１（１５）の条件で行った。 次に実施例２と同様な方法により、ａ−ＳｉＣからなるＲＦｐ型層３１１をＲＦＰＣＶＤ法によって形成した。
次に、ＲＦｐ型層３１１上に、透明導電層３１２として、層厚７０ｎｍのＩＴＯを真空蒸着法で真空蒸着した。
次に透明導電層３１２上に櫛型の穴が開いたマスクを乗せ、Ｃｒ（４０ｎｍ）／Ａｇ（１０００ｎｍ）／Ｃｒ（４０ｎｍ）からなる櫛形の集電電極３１３を真空蒸着法で真空蒸着した。
【０１９３】
以上で太陽電池の作製を終えた。この太陽電池を（ＳＣ実２１）と呼ぶことにし、本発明の微量第ＩＩＩ族元素含有水素プラズマ処理及び微量シラン系ガス含有水素プラズマ処理条件、ＲＦｎ型層、ｎ／ｉバッファー層、ＭＷｉ型層、ｐ／ｉバッファー層、ＲＦｉ型層、ＲＦｐ型層の形成条件を表２１（１）〜２１（１６）に示す。
【０１９４】
＜比較例２１＞
本発明の微量第ＩＩＩ族元素含有水素プラズマ処理及び微量シラン系ガス含有水素プラズマ処理を行わず、他は実施例２１と同じ条件で太陽電池（ＳＣ比２１）を作製した。
太陽電池（ＳＣ実２１）及び（ＳＣ比２１）はそれぞれ８個づつ作製し、初期光電変換効率（光起電力／入射光電力）、振動劣化、光劣化、バイアス電圧印加時の高温高湿環境における振動劣化、光劣化、及び逆方向バイアス電圧印加特性の測定を行なった。
【０１９５】
初期光電変換効率は、作製した太陽電池を、ＡＭ１．５（１００ｍＷ／ｃｍ^２）光照射下に設置して、Ｖ−Ｉ特性を測定することにより得られる。測定の結果、（ＳＣ比２１）に対して、（ＳＣ実２１）の初期光電変換効率の曲線因子（ＦＦ）、シリーズ抵抗（Ｒｓ）及び特性むらは以下のようになった。

振動劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を湿度５７％、温度２６℃の暗所に設置し、振動周波数６０Ｈｚで振幅０．１ｍｍの振動を５５０時間加えた後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（振動劣化試験後の光電変換効率／初期光電変換効率）により行った。光劣化の測定は、予め初期光電変換効率を測定しておいた太陽電池を、湿度５７％、温度２６℃の環境に設置し、ＡＭ１．５（１００ｍＷ／ｃｍ^２）光を５５０時間照射後の、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率の低下率（光劣化試験後の光電変換効率／初期光電変換効率）により行った。
【０１９６】
測定の結果、（ＳＣ実２１）に対して（ＳＣ比２１）の光劣化後の光電変換効率の低下率及び振動劣化後の光電変換効率の低下率は以下のようなった。

バイアス印加時の高温高湿度環境における振動劣化及び光劣化の測定を行った。予め初期光電変換効率を測定しておいた２つの太陽電池を湿度９４％温度８３℃の暗所に設置し、順方向バイアス電圧として０．７１Ｖを印加した。ー方の太陽電池には上記の振動を与えて、振動劣化を測定し、さらにもう一方の太陽電池にはＡＭ１．５の光を照射して、光劣化の測定を行った。
【０１９７】
測定の結果、（ＳＣ実２１）に対して、（ＳＣ比２１）の振動劣化後の光電変換効率の低下率及び光劣化後の光電変換効率の低下率は以下のようなった。

逆方向バイアス電圧印加特性の測定は、予め初期光電変換効率を測定しておいた太陽電池を湿度５２％、温度８０℃の暗所に設置し、逆方向バイアス電圧を５．０Ｖ、１００時間印加した後、ＡＭ１．５（１００ｍＷ／ｃｍ^２）照射下での光電変換効率を測定し、その低下率（逆方向バイアス電圧印加後の光電変換効率／初期光電変換効率）により行った。
【０１９８】
測定の結果、（ＳＣ実２１）に対して、（ＳＣ比２１）の逆方向バイアス電圧印加後の低下率は以下のようなった。
（ＳＣ比２１） ０．８３倍
光学顕微鏡を用いて層剥離の様子を観察した。（ＳＣ実２１）では層剥離は見られなかったが、（ＳＣ比２１）では層剥離が僅かに見られた。以上のように本発明の太陽電池（ＳＣ実２１）が、従来の太陽電池（ＳＣ比２１）よりも太陽電池の光電変換効率における曲線因子、シリーズ抵抗、特性むら、光劣化特性、密着性、耐久性、逆方向バイアス電圧印加特性においてさらに優れた特性を有することが分かった。
【０１９９】
以上の実施例では、基板上にｎ型層、ｎ／ｉバッファー層、ｉ型層、ｐ／ｉバッファー層、ｐ型層の順に積層した太陽電池について説明したが、基板上にｐ型層、ｐ／ｉバッファー層、ｉ型層、ｎ／ｉバッファー層、ｎ型層の順に積層した太陽電池についても、同様な水素プラズマ処理を行って太陽電池を作製した。
上記実施例と同様な評価を行ったところ、ｐ型層とｎ型層の間をシリコン原子含有ガス及び周期律表第ＩＩＩ族元素含有ガスを含む水素ガスでプラズマ処理した太陽電池は、光電変換効率における曲線因子、特性むら、光劣化特性、シリーズ抵抗特性、耐久性、逆方向バイアス電圧印加特性に優れた特性を有する事が確認された。また、基板とｐ型層の界面近傍、さらにはｎ／ｉバッファー層とｎ型層の接する界面近傍、またはｎ／ｉバッファー層とｉ型層の接する界面近傍、ｐ／ｉバッファー層とｉ型層の接する界面近傍、及びｐ／ｉバッファー層とｐ型層の接する界面近傍を、実質的に堆積しない程度のシリコン原子含有ガスを含有する水素ガスでプラズマ処理する事により上記特性はいっそう向上する事が分かった。
【０２００】
【表１（１）】

【０２０１】
【表１（２）】

【０２０２】
【表２（１）】

【０２０３】
【表２（２）】

【０２０４】
【表３（１）】

【０２０５】
【表３（２）】

【０２０６】
【表３（３）】

【０２０７】
【表４（１）】

【０２０８】
【表４（２）】

【０２０９】
【表４（３）】

【０２１０】
【表５（１）】

【０２１１】
【表５（２）】

【０２１２】
【表５（３）】

【０２１３】
【表６（１）】

【０２１４】
【表６（２）】

【０２１５】
【表６（３）】

【０２１６】
【表７（１）】

【０２１７】
【表７（２）】

【０２１８】
【表７（３）】

【０２１９】
【表８（１）】

【０２２０】
【表８（２）】

【０２２１】
【表８（３）】

【０２２２】
【表９（１）】

【０２２３】
【表９（２）】

【０２２４】
【表９（３）】

【０２２５】
【表１０（１）】

【０２２６】
【表１０（２）】

【０２２７】
【表１０（３）】

【０２２８】
【表１１（１）】

【０２２９】
【表１１（２）】

【０２３０】
【表１１（３）】

【０２３１】
【表１２（１）】

【０２３２】
【表１２（２）】

【０２３３】
【表１２（３）】

【０２３４】
【表１３（１）】

【０２３５】
【表１３（２）】

【０２３６】
【表１３（３）】

【０２３７】
【表１４（１）】

【０２３８】
【表１４（２）】

【０２３９】
【表１４（３）】

【０２４０】
【表１５（１）】

【０２４１】
【表１５（２）】

【０２４２】
【表１５（３）】

【０２４３】
【表１６（１）】

【０２４４】
【表１６（２）】

【０２４５】
【表１６（３）】

【０２４６】
【表１７（１）】

【０２４７】
【表１７（２）】

【０２４８】
【表１７（３）】

【０２４９】
【表１８（１）】

【０２５０】
【表１８（２）】

【０２５１】
【表１８（３）】

【０２５２】
【表１９（１）】

【０２５３】
【表１９（２）】

【０２５４】
【表１９（３）】

【０２５５】
【表２０（１）】

【０２５６】
【表２０（２）】

【０２５７】
【表２０（３）】

【０２５８】
【表２１（１）】

【０２５９】
【表２１（２）】

【０２６０】
【表２１（３）】

【０２６１】
【表２１（４）】

【０２６２】
【表２１（５）】

【０２６３】
【表２１（６）】

【０２６４】
【表２１（７）】

【０２６５】
【表２１（８）】

【０２６６】
【表２１（９）】

【０２６７】
【表２１（１０）】

【０２６８】
【表２１（１１）】

【０２６９】
【表２１（１２）】

【０２７０】
【表２１（１３）】

【０２７１】
【表２１（１４）】

【０２７２】
【表２１（１５）】

【０２７３】
【表２１（１６）】

【０２７４】
【発明の効果】
本発明により、通常水素プラズマ処理で見られる堆積チャンバー壁面に吸着または含まれている半導体層に取り込まれると欠陥準位となる不純物（例えば酸素、チッ素、炭素、鉄、クロム、二ッケル、アルミニウム等）を取り出してくるという問題点を解決することができる。また、安定した水素プラズマ処理を行う事が可能となる。この結果、
１）光起電力素子を高温高湿に置いた場合の半導体層の剥離の実質的にない光起電力素子を提供する事が可能となる。
【０２７５】
２）柔軟な基板上にｐｉｎ構造をを形成した場合に、基板を折り曲げてもｐｉｎ半導体層が剥離しにくい光起電力素子を提供する事ができる。
３）長時間の光照射によって基板と半導体層の界面近傍の欠陥準位の増加を抑制した光起電力素子を提供する事が可能となる。
４）高温高湿下で光照射した場合でも、基板と半導体層の剥離がなく、直列抵抗の増加等の特性低下を抑えた光起電力素子を提供する事が可能となる。
【０２７６】
５）高い温度で使用した場合でも、特性の低下の少ない光起電力素子を提供する事ができる。
６）光起電力素子に逆バイアスを印加した場合に、壊れにくい光起電力素子を提供することができる。
７）光起電力素子を形成した初期においても直列抵抗の小さい光起電力素子を提供できる。
【図面の簡単な説明】
【図１】本発明の光起電力素子の形成方法を適用した光起電力素子の模式的説明図である。
【図２】本発明の光起電力素子の形成方法を適用した他の光起電力素子の模式的説明図である。
【図３】本発明の光起電力素子の形成方法に適した光起電力素子の形成装置の模式的説明図である。
【符号の説明】
２００，３００ 支持体、
２０１，３０１ 反射層（または透明導電層）、
２０２，３０２ 反射増加層（または反射防止層）、
２０３，３０３ 第１のｎ型層（またはｐ型層）、
２０４，３０４ 第１のｉ型層、
２０５，３０５ 第１のｐ型層（またはｎ型層）、
２１２，３１２ 透明導電層（または導電層）、
２１３，３１３ 集電電極、
２５１，３５１ 第１のｎ／ｉバッファー層、
２６１，３６１ 第ｉのｐ／ｉバッファー層、
２０６，３０６ 第２のｎ型層（またはｐ型層）、
２０７，３０７ 第２のｉ型層、
２０８，３０８ 第２のｐ型層（またはｎ型層）、
２５２，３５２ 第２のｎ／ｉバッファー層、
２６２，３６２ 第２のｐ／ｉバッフアー層、
３０９ 第３のｎ（またはｐ型層）、
３１１ 第３のｐ型層（またはｎ型層）、
３１０ 第３のｉ型層、
３５３ 第３のｎ／ｉバッファー層、
３６３ 第３のｐ／ｉバッファー層、
４００ 形成装置、
４０１ ロードチャンバー、
４０２，４０３，４０４ 搬送チゃンバー、
４０５ アンロードチャンバー、
４０６，４０７，４０８，４０９ ゲートバルブ、
４１０，４１１，４１２ 基板加熱用ヒーター、
４１３ 基板搬送用レール、
４１７ ｎ型層（またはｐ型層）堆積チャンバー、
４１８ ｉ型層堆積チャンバー、
４１９ ｐ型層（またはｎ型層）堆積チャンバー、
４２０，４２１ プラズマ形成用カップ、
４２２，４２３，４２４ 電源、
４２５ マイクロ波導入用窓、
４２６ 導波管、
４２７ シャッタ、
４２８ バイアス棒、
４２９，４４９，４６９ ガス導入管、
４３０，４３１，４３２，４３３，４３４，４４１，４４２，４４３，４４４， ４５０，４５１，４５２，４５３，４５４，４５５，４６１，４６２，４６３， ４６４，４６５，４６８，４６６，４７０，４７１，４７２，４７３，４７４， ４８１，４８２，４８３，４８４ バルブ、
４３６，４３７，４３８，４３９，４５６，４５７，４５８，４５９，４６０， ４６７，４７６，４７７，４７８，４７９ マスフローコントローラ、
４９０ 基板ホルダー。[0001]
[Industrial applications]
The present invention provides a pin structure formed by laminating a non-single-crystal n-type layer (or p-type layer) containing silicon atoms, a non-single-crystal i-type layer, and a non-single-crystal p-type layer (or n-type layer), The present invention relates to a method for forming a photovoltaic element such as a solar cell or a sensor formed by stacking at least two or more components.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, defects existing in a semiconductor are closely related to generation of electric charge and recombination, and deteriorate the characteristics of an element.
As a method for compensating for such a defect level, a hydrogen plasma treatment has been proposed. For example, US Pat. No. 4,113,514 (JI Pankove et al., RCA Sep. 12, 1978) describes hydrogen plasma treatment of a completed semiconductor device. In addition, "EFFECT OF PLASMA TREAMENT OF THE TCO ON a-Si SOLAR CELL PERFORMANCE", F.S. Demichelis et. al. , Mat. Res. Soc. Symp. Proc. Vol. 258, p9O5, 1992 show a method of forming a solar cell having a pin structure on a transparent electrode deposited on a substrate by a hydrogen plasma treatment. Further, "HYDROGEN-PLASMA RECTION FLUSHING F0R a-Si: HPIN SOLAR CELL FABRlCATION", Y. S. Tsuo et. al. , Mat. Res. Soc. Symp. Proc. Vol. 149, p471, 1989, show that in a solar cell having a pin structure, the surface of the p-layer is subjected to hydrogen plasma treatment before the deposition of the i-layer. In the conventional hydrogen plasma processing as described above, only the hydrogen gas is introduced into the chamber, and the hydrogen gas is activated by the RF power to perform the hydrogen plasma processing.
[0003]
The hydrogen plasma spreads not only to act on the substrate to be processed, the unfinished device, the finished device, but also throughout the chamber. Since hydrogen plasma is very active, impurities (such as oxygen, nitrogen, carbon, iron, chromium, and nickel) adsorbed or contained on the wall of the chamber and become defect levels when incorporated into the semiconductor layer are absorbed from the wall of the chamber. , Aluminum, etc.).
[0004]
In addition, hydrogen gas is more difficult to cause discharge than other gases, and plasma using only hydrogen gas is more difficult to maintain plasma than other gases, so that stable hydrogen plasma processing cannot be performed. There is.
Further, in a photovoltaic device having a plurality of pin structures stacked, a group III element and a group V element of the periodic table interdiffuse in the vicinity of the interface between the p-type layer and the n-type layer in contact with the pin structure and have a high resistance. Is formed, and there is a problem that the characteristics of photoelectrons are deteriorated.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above problems. That is, an object of the present invention is to provide a hydrogen plasma processing method in which the absorption of impurities contained in or contained in a chamber wall does not substantially occur, and a method for performing a more stable hydrogen plasma processing. is there.
[0006]
It is another object of the present invention to provide a method for forming a photovoltaic element in which the semiconductor layer does not substantially peel even when the photovoltaic element is placed at high temperature and high humidity.
It is a further object of the present invention to provide a method for forming a photovoltaic element in which a pin semiconductor layer is not easily peeled off even when a pin structure is formed on a flexible substrate.
[0007]
Still further, an object of the present invention is to provide a photovoltaic element that suppresses deterioration in characteristics of the photovoltaic element such as separation of a substrate and a semiconductor layer and an increase in series resistance when irradiated with light under high temperature and high humidity. It is to provide a forming method.
It is another object of the present invention to provide a photovoltaic element in which the characteristics are less deteriorated when used at a high temperature.
[0008]
An object of the present invention is to provide a photovoltaic device having improved initial efficiency by preventing diffusion of impurities from a p-type layer to an i-type layer.
An object of the present invention is to provide a photovoltaic element that is not easily broken when a reverse bias is applied to the photovoltaic element.
An object of the present invention is to form a high-resistance layer near the interface by distributing the distribution of the Group III element of the periodic table so as to change rapidly near the interface between the p-type layer and the n-type layer. It is to provide a photovoltaic element which is not used.
[0009]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the above object can be achieved by a method of forming between a p-type layer and an n-type layer.
That is, the present invention provides a non-single-crystal n-type layer (or p-type layer) containing silicon atoms, a non-single-crystal i-type n / i buffer layer (or p / i buffer layer), A pin structure formed by laminating a crystalline i-type layer, a non-single-crystal i-type p / i buffer layer (or n / i buffer layer), and a non-single-crystal p-type layer (or n-type layer) has at least two or more configurations. In the method for forming a stacked photovoltaic element, the vicinity of the interface where the p-type layer and the n-type layer are in contact with each other contains a silicon atom-containing gas and a group III element-containing gas in the periodic table that do not substantially deposit. It is characterized by performing a plasma treatment with a hydrogen gas.
[0010]
Further, in the present invention, the vicinity of the interface between the substrate and the n-type layer (or the vicinity of the interface between the substrate and the p-type layer) is subjected to a plasma treatment with a hydrogen gas containing a gas containing silicon atoms to such an extent that substantially no deposition occurs. It is characterized by doing.
Still further, in the present invention, the vicinity of the interface where the n / i buffer layer contacts the n-type layer, the vicinity of the interface where the n / i buffer layer contacts the i-type layer, and the contact of the p / i buffer layer and the i-type layer. The plasma processing is performed on the vicinity of the interface and the vicinity of the interface where the p / i buffer layer and the p-type layer are in contact with each other with a hydrogen gas containing a silicon atom-containing gas to such an extent that substantially no deposition occurs.
[0011]
Also, in the present invention, the silicon atom-containing gas is SiH₄, Si₂H₆, SiF₄, SiFH₃, SiF₂H₂, SiF₃H, SiC₂H₂, SiCl₃H, SiCl₄Is characterized by including at least one of them.
The present invention is further characterized in that the content of the silicon atom-containing gas with respect to hydrogen gas is 0.1% or less.
[0012]
[Action]
The object can be solved by forming a photovoltaic element by adding a silicon-containing gas to a hydrogen gas so as not to substantially contribute to the deposition, performing a hydrogen plasma treatment, and then depositing a semiconductor layer. The detailed mechanism is not clear at present, but the present inventors consider as follows.
[0013]
That is, when hydrogen gas is added to the hydrogen gas to such an extent that the silicon atom-containing gas does not substantially contribute to the deposition, the activated silicon atom-containing gas is exposed to oxygen or water adsorbed on the inner wall of the chamber. To form stable silicon oxide and the like, which is more stable than adsorbed on the inner wall of the chamber in the form of oxygen or water. As a result, the silicon atom-containing gas is contained to such an extent that it does not substantially contribute to deposition, and when plasma processing is performed, the incorporation of impurities such as oxygen and water adsorbed on the chamber wall surface into the semiconductor is suppressed to a very low level. It is thought that things can be done.
[0014]
In addition, when hydrogen plasma treatment is performed with hydrogen gas containing a small amount of silicon atom-containing gas, hydrogen atoms are prevented from diffusing deeply into the chamber wall on the chamber wall, and semiconductor It is considered that a reaction such as taking out an impurity which enters the layer and forms a defect level can be suppressed as much as possible.
[0015]
In addition, hydrogen gas has high ionization energy and it is difficult to maintain plasma discharge stably for a long time, but by adding a small amount of silicon atom-containing gas that easily maintains plasma discharge to hydrogen gas as in the present invention, It is considered that the maintenance of the plasma discharge of hydrogen gas is facilitated. By applying such a very stable hydrogen plasma discharge to a substrate or an element, the uniformity and reproducibility of the hydrogen plasma treatment are greatly improved. By improving the uniformity and reproducibility of the hydrogen plasma treatment, it is possible to prevent local separation of the semiconductor layer and increase in series resistance under high temperature, high humidity and light irradiation for a long time on substrates and elements that have been subjected to the hydrogen plasma treatment. You can do it.
[0016]
The hydrogen plasma treatment of the present invention has a textured structure on the surface of the substrate, and works in a direction in which the textured structure is locally sharply developed, so that it contains a silicon atom-containing gas and becomes dull. It is. As a result, abnormal growth of the semiconductor layer can be substantially prevented even if the semiconductor layer is deposited on the substrate having the texture structure subjected to the hydrogen plasma treatment of the present invention. Therefore, when a photovoltaic device having a pin structure is formed, the photovoltaic device has less characteristic unevenness, excellent adhesion between the substrate and the semiconductor layer, and excellent durability under high temperature and high humidity. Is obtained.
[0017]
When the hydrogen plasma treatment of the present invention is performed in the vicinity of the interface between the p-type layer and the n-type layer, defects near the interface can be reduced, and the transfer of charges excited by light can be facilitated. In particular, silicon atom-containing active species generated by plasma from silicon atom-containing gas to such an extent that substantially no deposition occurs collide with or replace silicon atoms on the surface subjected to the hydrogen plasma treatment, and the structural relaxation progresses, and the surface state is reduced. Is improved. In particular, when light is irradiated from the p-type layer, many charges excited by light are generated on the p-layer side, so that many defects are likely to be generated on the p-layer side. This can be alleviated by performing near the interface between the p-type layer and the n-type layer. Also, in the p-type layer which is p-type with B having a small atomic radius, when the free charge excited by light increases, the diffusion of B is promoted, and the characteristics of the photovoltaic element deteriorate. This can be prevented by performing the hydrogen plasma treatment of the present invention near the interface between the p-type layer and the n-type layer. As a result, in the photovoltaic device that has been subjected to the hydrogen plasma treatment of the present invention, the photovoltaic device is less likely to break when a reverse bias is applied to the photovoltaic device.
[0018]
Further, when the hydrogen plasma treatment of the present invention is performed near the interface between the p-type layer and the n-type layer, mutual diffusion of the group III element of the periodic table and the group V element of the periodic table can be prevented. The formation of a high-resistance layer near the interface between the mold layer and the n-type layer can be prevented. As a result, the series resistance can be reduced.
When the hydrogen plasma treatment of the present invention is performed at the interface between the p / i buffer layer and the p-type layer, defects near the interface can be reduced, and the transfer of charges excited by light can be facilitated. . In particular, silicon atom-containing active species generated by plasma from silicon atom-containing gas to such an extent that substantially no deposition occurs collide with or replace silicon atoms on the surface subjected to the hydrogen plasma treatment, and the structural relaxation progresses, and the surface state is reduced. Is improved.
[0019]
[Example of embodiment]
Hereinafter, embodiments of the present invention will be described in detail.
First, a method and an apparatus for forming a photovoltaic element of the present invention will be described in detail with reference to the drawings.
(Hydrogen plasma processing conditions)
FIGS. 1 and 2 show an example of a photovoltaic element of the present invention in which a hydrogen plasma treatment is performed with a hydrogen gas containing a trace amount of a silicon atom-containing gas.
[0020]
FIG. 1 is a schematic explanatory view of a photovoltaic element having two pin structures. The photovoltaic element includes a substrate 290 (support 200, reflection layer 201, reflection enhancement layer 202), a first n-type layer (or p-type layer) 203, a first n / i buffer layer (or p / i buffer layer) 251, first i type layer 204, first p / i buffer layer (or n / i buffer layer) 261, first p type layer (or n type layer) 205, second n Mold layer (or p-type layer) 206, second n / i buffer layer (or p / i buffer layer) 252, second i-type layer 207, second p / i buffer layer (or n / i buffer) Layer 262, a second p-type layer (or n-type layer) 208, a transparent electrode 212, and a current collecting electrode 213. When light is irradiated from the substrate side, 200 is a light-transmitting support, 201 is a transparent conductive layer, 202 is an antireflection layer, and 212 is a conductive layer also serving as a reflective layer.
[0021]
FIG. 2 is a schematic explanatory view of a photovoltaic element having three pin structures. The photovoltaic element includes a substrate 390 (a support 300, a reflective layer 301, and a reflection enhancing layer 302), a first n-type layer (or p-type layer) 303, and a first n / i buffer layer (or p / i-buffer layer) 351, first i-type layer 304, first p / i buffer layer (or n / i buffer layer) 361, first p-type layer (or n-type layer) 305, second n Mold layer (or p-type layer) 306, second n / i buffer layer (or p / i buffer layer) 352, second i-type layer 307, second p / i buffer layer (or n / i buffer) Layer) 362, second p-type layer (or n-type layer) 308, third n-type layer (or p-type layer) 309, third n / i buffer layer (or p / i buffer layer) 353, Third i-type layer 310, third p / i buffer layer (or n / i buffer ) 363, a third p-type layer (or n-type layer) 311, transparent electrode 312, and a collecting electrode 313. When light is irradiated from the substrate side, 300 is a light-transmitting support, 301 is a transparent conductive layer, 302 is an antireflection layer, and 312 is a conductive layer also serving as a reflective layer.
[0022]
In the present invention, the plasma treatment with a hydrogen gas containing a silicon atom-containing gas and a gas containing a Group III element in the periodic table that does not substantially deposit is preferably performed near the interface between the p-type layer and the n-type layer. It is effective. The hydrogen flow rate suitable for achieving the object of the present invention is appropriately optimized depending on the size of the processing chamber, and the suitable flow rate is 1 to 2000 sccm. When the hydrogen flow rate is less than 1 sccm, the power for maintaining the plasma discharge increases, the damage to the base slope becomes severe, and impurities are easily taken in from the chamber wall. When the flow rate of hydrogen is more than 2000 sccm, the residence time of the silicon-based active species and the active species of hydrogen in the plasma discharge in the chamber is shortened. The effect of the plasma treatment at the step becomes difficult to appear.
[0023]
In the hydrogen plasma processing method of the present invention, the preferable addition amount of the silicon atom-containing gas added to the hydrogen gas is 0.001% to 0.1%. If the addition amount of the silicon atom-containing gas to the hydrogen gas is less than 0.001%, the effect of the present invention will not be exhibited, and if it is more than 0.1%, the deposition of silicon atoms will increase. The effect of is no longer apparent.
[0024]
In the hydrogen plasma treatment method of the present invention, the ratio of the Group III element containing gas added to the hydrogen gas is preferably in the range of 0.05 to 3%. By treating the vicinity of the interface between the p-type layer and the n-type layer with a hydrogen plasma containing a Group III element in the periodic table and containing silicon atoms to such an extent that substantially no deposition occurs, the vicinity of the interface can be improved. Can sharply change the distribution of Group III elements in the periodic table. In addition, the hydrogen plasma treatment of the present invention improves the activation rate of the Group III element of the periodic table near the interface, and is particularly important for the photovoltaic power of the pin structure, which is the interface between the p-type layer and the n-type layer. In the vicinity, the addition amount and the activation rate of the group III element of the periodic table are increased, so that the series resistance is reduced and the characteristics as a photovoltaic element are improved. Further, when the hydrogen plasma treatment of the present invention is performed on the p-type layer at a relatively low temperature (280 ° C. or lower), the diffusion of Group III of the periodic table into the n-type layer is substantially almost impossible. In addition, it is possible to make the Group III element of the periodic table exist at a high concentration and a high activation rate in the vicinity of the very surface of the p-type layer. As described above, in the hydrogen plasma treatment of the present invention, the Group III element of the periodic table can be contained in an extremely large amount and at a high activation rate near the interface between the p-type layer and the n-type layer. The thickness can be reduced, and the light applied to the photovoltaic element can be used more effectively.
[0025]
The energy suitable for generating the hydrogen plasma of the present invention is an electromagnetic wave, particularly RF (radio frequency), VHF (very high frequency), and MW (microwave). When the hydrogen plasma treatment of the present invention is performed by RF, a preferable frequency range is 1 MHz to 50 MHz. When the hydrogen plasma treatment of the present invention is performed by VHF, a preferable frequency range is from 51 MHz to 500 MHz. When the hydrogen plasma treatment of the present invention is performed by MW, a preferable frequency range is from 0.51 GHz to 10 GHz.
[0026]
In order to effectively perform the hydrogen plasma treatment of the present invention, the degree of vacuum is an important factor, and the preferable range largely depends on the energy used to activate the hydrogen gas to which the silicon atom-containing gas is added. Is what you do. When the hydrogen plasma treatment is performed in the RF frequency band, the degree of vacuum is preferably in the range of 0.05 Torr to 10 Torr. The preferred degree of vacuum when performing hydrogen plasma processing in the VHF frequency band is in the range of 0.0001 Torr to 1 Torr. A preferred degree of vacuum when performing the hydrogen plasma treatment in the MW frequency band is in the range of 0.0001 Torr to 0.01 Torr.
[0027]
In the hydrogen plasma processing of the present invention, the power density supplied into the chamber to generate hydrogen plasma is an important factor for effectively performing the hydrogen plasma processing of the present invention. Such power density depends on the frequency of the electromagnetic wave used. When using the RF frequency band, the power density is 0.01 to 1 W / cm.³Is a preferable range. When using the VHF frequency band, 0.01 to 1 W / cm³Is a preferable range. In particular, in the case of the VHF frequency band, the plasma discharge can be maintained in a wide pressure range, and when performing the hydrogen plasma processing at a high pressure, it is preferable to perform the hydrogen plasma processing at a relatively low power density. On the other hand, when the hydrogen plasma treatment is performed at a low pressure, it is preferable to perform the treatment at a relatively high power density. When performing the hydrogen plasma treatment of the present invention using the MW frequency band, 0.1 to 10 W / cm³Is a preferable power density range. In performing the hydrogen plasma treatment of the present invention, there is a close relationship between the power density and the hydrogen plasma treatment time, and when the power density is high, the relatively short hydrogen plasma treatment time is preferable. is there.
[0028]
In the hydrogen plasma processing of the present invention, the substrate temperature during the hydrogen plasma processing is a very important factor for making the effects of the present invention effective. In the case where the hydrogen plasma treatment is performed using the RF frequency band, the substrate temperature is preferably relatively high, and the preferable temperature range is 100 to 400 ° C. When performing the hydrogen plasma treatment of the present invention using the VHF or MW frequency band, the substrate temperature is preferably relatively low. In this case, 50 to 300 ° C. is a preferable temperature range. Further, the substrate temperature during the hydrogen plasma treatment of the present invention also depends closely on the power density input into the chamber, and when the input power density is relatively high, the substrate temperature is set to a lower temperature. Is preferred.
[0029]
When performing the hydrogen plasma treatment of the present invention, the power density, gas flow rate, substrate temperature, pressure, and the like as described above may be changed with respect to the treatment time. Usually, a substrate has many defects and many impurities near its surface. Therefore, the hydrogen plasma treatment is preferably performed at a relatively high power density and a high pressure at the start of the treatment.
[0030]
In the hydrogen plasma treatment of the present invention, the silicon atom-containing gas added to the hydrogen gas is SiH₄, Si₂H₆, SiF₄, SiF₃H, SiF₂H₂, SiF₃H, Si₂FH5, SiCl₄, SiClH₃, SiCl₂H₂, SlClH₃And the like are suitable. These silicon atom-containing gases may be added alone to the hydrogen gas, or may be added in combination of two or more. In particular, the mixing ratio of a silicon atom-containing gas containing a halogen atom is preferably added more than a silicon atom-containing gas not containing a halogen atom.
[0031]
(Formation method and apparatus)
A method for forming a photovoltaic element of the present invention and a forming apparatus suitable for the method will be described. An example of the forming apparatus is shown in a schematic explanatory view of FIG.
3, a forming apparatus 400 includes a load chamber 401, transfer chambers 402, 403, and 404, an unload chamber 405, gate valves 406, 407, 408, and 409, substrate heaters 410, 411, and 412, and a substrate transfer rail. 413, an n-type layer (or p-type layer) deposition chamber 417, an i-type layer deposition chamber 418, a p-type layer (or n-type layer) deposition chamber 419, plasma forming cups 420, 421, power supplies 422, 423, 424, Microwave introduction window 425, waveguide 426, gas introduction tubes 429, 449, 469, valves 430, 431, 432, 433, 434, 441, 442, 443, 444, 450, 451, 452, 453, 454, 455, 461, 462, 463, 464, 465, 470, 471, 72, 473, 474, 481, 482, 483, 484, mass flow controllers 436, 437, 438, 439, 456, 457, 458, 459, 460, 476, 477, 478, 479, shutter 427, bias rod 428, substrate It comprises a holder 490, an exhaust device (not shown), a microwave power supply (not shown), a vacuum gauge (not shown), a control device (not shown), and the like.
[0032]
A method for forming a photovoltaic element to which the hydrogen plasma processing method of the present invention is applied is performed as follows using a forming apparatus shown in FIG.
All chambers of the deposition apparatus 400 are connected to each chamber by a turbo-molecular pump (not shown).^-6Raise the vacuum to Torr or less.
When the hydrogen plasma treatment of the present invention is performed by RF, it is performed as follows. A base layer on which a reflective layer of silver or the like is deposited on a stainless steel support and a reflection-enhancing layer of zinc oxide or the like is further deposited is attached to a base holder 490. The substrate holder 490 is put into the load chamber 401. The door of the load chamber 401 is closed, and the load chamber 401 is pulled up to a predetermined degree of vacuum by a mechanical booster pump / rotary pump (MP / RP) (not shown). When the load chamber reaches a predetermined degree of vacuum, the MP / RP is switched to a turbo molecular pump and 10^-6Raise the vacuum to Torr or less. 10 load chambers^-6When the degree of vacuum becomes equal to or lower than Torr, the gate valve 406 is opened, the substrate holder 490 on the substrate transfer rail 413 is moved to the transfer chamber 402, and the gate valve 406 is closed. The substrate heating heater 410 of the transfer chamber 402 is raised so that the substrate holder 490 does not hit. The position of the substrate holder is determined so that the substrate comes directly under the heater. The substrate heating heater 410 is lowered, and the substrate is put into the n-type layer deposition chamber.
[0033]
The substrate temperature is changed to a temperature suitable for the deposition of the n-type layer, and the SiH₄, Si₂H₆A silicon atom-containing gas and a gas containing a Group V element of the periodic table for n-type layer deposition are introduced into the deposition chamber 417 via a valve 443, a mass flow controller 438, and a valve 433. It is also preferable that the flow rate of the hydrogen gas is appropriately adjusted in accordance with the n-type layer. In this manner, the source gas for depositing the n-type layer is introduced into the deposition chamber 417, and the degree of opening and closing of the exhaust valve (not shown) is changed to make the inside of the deposition chamber 417 a desired degree of vacuum of 0.1 to 10 Torr. Then, RF power is introduced from the RF power supply 422 to the plasma forming cup 420 to cause plasma discharge and maintain the discharge for a desired time. Thus, an n-type semiconductor layer having a desired thickness is deposited on the substrate.
[0034]
After the deposition of the n-type layer is completed, the introduction of the source gas into the deposition chamber 417 is stopped, and the inside of the chamber is purged with hydrogen gas or helium gas. After sufficient purging, supply of hydrogen gas or helium gas is stopped, and the inside of the deposition chamber is^-6Raise to Torr. The gate valve 407 is opened, the substrate holder 490 is moved to the transfer chamber 403, and the gate valve 407 is closed. The position of the substrate holder is adjusted so that the substrate can be heated by the substrate heating heater 411. A substrate heating heater is brought into contact with the substrate to heat the substrate to a predetermined temperature. At the same time, an inert gas such as a hydrogen gas or a helium gas is introduced into the deposition chamber 418. Further, it is preferable that the degree of vacuum at that time is the same as that at the time of depositing the n / i buffer layer. When the substrate temperature reaches a desired temperature, the gas for heating the substrate is stopped, and the source gas for depositing the n / i buffer layer is supplied to the deposition chamber 418 from the gas supply device. For example, hydrogen gas, silane gas, and germane gas are set as desired with the mass flow controllers 457, 458, and 459 by opening the valves 462, 463, and 464, respectively, and the valves 452, 453, 454, and 450 are opened, and the gas is introduced through the gas introduction pipe 449. And supply it to the deposition chamber 418. At the same time, the supply gas is evacuated by a diffusion pump (not shown) so that the degree of vacuum in the deposition chamber 418 becomes a desired pressure. When the degree of vacuum in the chamber 418 is stabilized at a desired degree of vacuum, desired power is introduced from a RF power supply (not shown) into a bias rod for applying a bias. Then, an n / i buffer layer is deposited by RF plasma CVD. Preferably, the n / i buffer layer is deposited at a lower deposition rate than the i-type layer deposited thereafter.
[0035]
Next, the substrate is heated to a predetermined temperature for i-type layer deposition. Preferably, the substrate is heated while an inert gas such as a hydrogen gas or a helium gas is opened by opening a valve 461, a desired flow rate is set by a mass flow controller, and valves 451 and 450 are opened. Further, it is preferable that the degree of vacuum at that time is the same as that at the time of depositing the i-type layer.
[0036]
When the substrate temperature reaches a desired temperature, the gas for heating the substrate is stopped, and the source gas for depositing the i-type layer is supplied to the deposition chamber 418 from the gas supply device. For example, hydrogen gas, silane gas, and germane gas are opened at the respective valves 462, 463, and 464, and the desired flow rates are set at the mass flow controllers 457, 458, and 459, and the valves 452, 453, 454, and 450 are opened, and the gas introduction pipe 449 is opened. To the deposition chamber 418. At the same time, the supply gas is evacuated by a diffusion pump (not shown) so that the degree of vacuum in the deposition chamber 418 becomes a desired pressure. When the degree of vacuum in the chamber 418 is stabilized at a desired degree of vacuum, desired power is introduced from a microwave power supply (not shown) into the deposition chamber 418 via the waveguide 426 and the microwave introduction window 425. Simultaneously with the introduction of the microwave energy, it is also preferable to introduce the desired bias power into the deposition chamber 418 from an external DC, RF or VHF power supply 424 to the biasing bias bar, as shown in an enlarged view of the deposition chamber 418. Things. Thus, the i-type layer is deposited to a desired thickness. When the i-type layer has been deposited to a desired thickness, the application of microwave power and bias is stopped. If necessary, the inside of the deposition chamber 418 is purged with an inert gas such as hydrogen gas or helium gas.
[0037]
Thereafter, a p / i buffer layer is deposited to a desired thickness in the same manner as the deposition of the n / i buffer layer. Thereafter, if necessary, the inside of the deposition chamber 418 is purged with an inert gas such as a hydrogen gas or a helium gas.
The inside of the deposition chamber was purged, the exhaust was changed from a diffusion pump to a turbo molecular pump, and the degree of vacuum in the deposition chamber was reduced to 10^-6The degree of vacuum is set to Torr or less. At the same time, the heater for heating the substrate is raised so that the substrate holder can be moved. The gate valve 408 is opened, the base holder is moved from the transfer chamber 403 to the transfer chamber 404, and the gate valve 408 is closed.
[0038]
The substrate holder is moved directly below the substrate heating heater 412, and the substrate is heated by the base heating heater 412. It is more preferable that the substrate be heated by changing the exhaust from the turbo molecular pump to MP / RP and flowing an inert gas such as a hydrogen gas or a helium gas to a pressure at the time of deposition of the p-type layer during heating. is there. When the substrate temperature is stabilized at a desired substrate temperature, supply of a substrate heating gas such as a hydrogen gas or an inert gas for substrate heating is stopped, and a source gas for p-type layer deposition, for example, H₂, SiH₄, BF₃Gases containing a Group III element such as the periodic table are opened through valves 482, 483, and 484, and further opened through valves 472, 473, and 474 via mass flow controllers 477, 478, and 479, and are introduced into the deposition chamber 419. The desired flow rate is supplied through 469. The exhaust valve is adjusted so that the internal pressure of the deposition chamber 419 becomes a desired degree of vacuum. When the internal pressure of the deposition chamber 419 is stabilized at a desired degree of vacuum, RF power is supplied from the RF power supply 423 to the plasma forming cup. The p-type layer is then deposited for the desired time. After the deposition, the supply of the RF power and the source gas is stopped, and the inside of the deposition chamber is sufficiently purged with an inert gas such as a hydrogen gas or a helium gas.
[0039]
The hydrogen plasma treatment of the present invention is performed on a p-type layer as follows. In the chamber, hydrogen gas, silicon atom-containing gas, and group III element containing gas required for performing the hydrogen plasma treatment of the present invention are supplied to valves 471, 472, 473, mass flow controllers 476, 479, 478, valve 481, A predetermined flow rate is introduced into the deposition chamber 419 via 482, 483 and the valve 470. The degree of vacuum is changed in the deposition chamber 419 by changing the opening / closing degree of an exhaust valve (not shown). When the degree of vacuum in the chamber 419 is stabilized, RF power is supplied from the RF power supply 423 to the plasma forming cup 421 to generate plasma. In this manner, the hydrogen plasma treatment of the present invention is performed for a predetermined time. It is desirable to appropriately change the flow rate of the hydrogen gas, the flow rate of the silicon atom-containing gas, the RF power, the substrate temperature, etc. during the hydrogen plasma treatment depending on the surface state of the base slope and the state of the inner wall of the chamber. is there. The preferred form of variation of these parameters is to initially increase the hydrogen flow and decrease the hydrogen flow over time. As a form of the change in the flow rate of the silicon atom-containing gas, the flow rate of the silicon atom-containing gas is initially small and the flow rate of the silicon atom-containing gas is increased with time. A preferred form of change is that the RF power is initially high and then reduced over time.
[0040]
After performing the plasma treatment of the present invention on the p-type layer in this manner, a pin structure is formed in the same manner as described above.
After the final p-type layer is laminated and the purging is completed, the evacuation is changed from MP / RP to turbo molecular pump to 10^-6Evacuate to a vacuum of Torr or less. At the same time, the heater 412 for heating the substrate is raised, the gate valve 409 is opened, and the substrate holder 490 is moved to the unload chamber 405. The gate valve 409 is closed, and when the temperature of the substrate holder becomes 100 ° C. or less, the door of the unload chamber is opened and taken out. Thus, a pin semiconductor layer subjected to the hydrogen plasma treatment of the present invention is formed. The substrate on which the pin semiconductor layer is formed is set in a vacuum evaporator for depositing a transparent electrode, and a transparent electrode is formed on the semiconductor layer. Next, the photovoltaic element on which the transparent electrode is formed is set in a vacuum evaporator for depositing a collecting electrode, and the collecting electrode is deposited. Thus, a photovoltaic element is formed.
[0041]
When the hydrogen plasma treatment of the present invention is performed by MW, for example, it is performed as follows. After depositing the p-type layer, the gate valve 408 is opened, the substrate holder 490 is moved to the transfer chamber 403, and the gate valve is closed. The position of the substrate holder is determined so that the substrate comes directly under the heater. The substrate heating heater 411 is lowered, and the substrate is put into the i-type layer deposition chamber. The substrate temperature is raised to a desired substrate temperature by the substrate heater 411. The turbo molecular pump is switched to MP / RP, and hydrogen gas, a silicon atom-containing gas, and a group III element-containing gas of the periodic table necessary for performing the hydrogen plasma treatment of the present invention are supplied to the chamber by valves 461, 462, 463, A predetermined flow rate is introduced into the deposition chamber 418 via the mass flow controllers 456, 457, 458, the valves 451, 452, 453, and the valve 450. The inside of the deposition chamber 418 is set to a desired degree of vacuum by changing the opening / closing degree of an exhaust valve (not shown). When the degree of vacuum in the chamber 418 is stabilized, MW power is supplied from a MW power supply (not shown) to the deposition chamber 418 through the microwave introduction window 425 to generate plasma. In this manner, the hydrogen plasma treatment of the present invention is performed for a predetermined time. Depending on the surface state of the substrate and the state of the inner wall of the chamber, it is desirable to appropriately change the flow rate of the hydrogen gas, the flow rate of the silicon atom-containing gas, the MW power, the substrate temperature, etc. during the hydrogen plasma treatment. . The preferred form of variation of these parameters is to initially increase the hydrogen flow and decrease the hydrogen flow over time. As a form of the change in the flow rate of the silicon atom-containing gas, the flow rate of the silicon atom-containing gas is initially small and the flow rate of the silicon atom-containing gas is increased with time. A preferred form of change is that the MW power is initially high and then reduced over time. When performing the hydrogen plasma treatment of the present invention with VHF, it is preferable to perform the same treatment as with MW.
[0042]
Further, it is also preferable to perform a hydrogen plasma treatment on the vicinity of the interface between the substrate and the n-type layer with a hydrogen gas containing a gas that does not substantially deposit a silicon atom-containing gas. To perform the hydrogen plasma treatment near the interface between the substrate and the n-type layer, the substrate is transported to the n-type layer deposition chamber or the i-type layer deposition chamber in the above-described procedure, and the substrate is maintained at a predetermined substrate temperature. In the above procedure, a predetermined flow rate of the silicon atom-containing gas and the hydrogen gas is introduced into the deposition chamber. The pressure is adjusted by the pressure adjusting valve so that the degree of vacuum is appropriate for the type of the introduced power such as RF, VHF and / or MW power. A plasma discharge is generated by introducing RF, VHF or / and MW power, and the hydrogen plasma treatment of the present invention is performed on the substrate for a predetermined time.
[0043]
In addition, the characteristics of the photovoltaic element are further improved by performing a plasma treatment on the vicinity of the interface between the n / i buffer layer and the i-type layer with a hydrogen gas that does not contribute to the deposition of the silicon atom-containing gas. However, the hydrogen plasma treatment of the present invention is performed on the n / i-type layer as follows. A predetermined amount of hydrogen gas and a gas containing silicon atoms required for performing the hydrogen plasma treatment of the present invention are supplied to the deposition chamber 418 via valves 461 and 462, mass flow controllers 456 and 457, valves 451 and 452, and a valve 450. To be introduced. The inside of the deposition chamber 418 is set to a desired degree of vacuum by changing the opening / closing degree of an exhaust valve (not shown). When the degree of vacuum in the chamber 418 is stabilized, RF power is supplied from the RF power supply 424 to the bias power supply 428 to generate plasma. In this manner, the hydrogen plasma treatment of the present invention is performed for a predetermined time. Depending on the surface state of the substrate and the state of the inner wall of the chamber, it is desirable to appropriately change the flow rate of the hydrogen gas, the flow rate of the silicon atom-containing gas, the RF power, the base temperature, etc. during the hydrogen plasma treatment. is there. The preferred form of variation of these parameters is to initially increase the hydrogen flow and decrease the hydrogen flow over time. As a form of the change in the flow rate of the silicon atom-containing gas, the flow rate of the silicon atom-containing gas is initially small and the flow rate of the silicon atom-containing gas is increased with time. A preferred form of change is that the RF power is initially high and then reduced over time.
The hydrogen plasma treatment of the present invention is performed on the i-type layer as follows. A predetermined amount of hydrogen gas and a silicon atom-containing gas required for performing the hydrogen plasma treatment of the present invention are supplied to the deposition chamber 418 through valves 461 and 462, mass flows 456 and 457, valves 451 and 452, and a valve 450. Introduce. The inside of the deposition chamber 418 is set to a desired degree of vacuum by changing the opening / closing degree of an exhaust valve (not shown). When the degree of vacuum in the chamber 418 becomes stable, RF power is introduced from the RF power supply 424 to the bias rod 428 to generate plasma. In this manner, the hydrogen plasma treatment of the present invention is performed for a predetermined time. Depending on the surface state of the substrate and the state of the inner wall of the chamber, it is desirable to appropriately change the flow rate of the hydrogen gas, the flow rate of the silicon atom-containing gas, the RF power, the substrate temperature, etc. during the hydrogen plasma treatment. . The preferred form of variation of these parameters is to initially increase the hydrogen flow and decrease the hydrogen flow over time. As a form of the change in the flow rate of the silicon atom-containing gas, the flow rate of the silicon atom-containing gas is initially small and the flow rate of the silicon atom-containing gas is increased with time. A preferred form of change is that the RF power is initially high and then reduced over time.
[0044]
The hydrogen plasma treatment of the present invention on the p / i buffer layer is performed as follows. A predetermined amount of hydrogen gas and a gas containing silicon atoms required for performing the hydrogen plasma treatment of the present invention are supplied to the deposition chamber 418 through valves 461 and 462, mass flow controllers 456 and 457, valves 451 and 452, and a valve 450. To be introduced. The inside of the deposition chamber 418 is set to a desired degree of vacuum by changing the opening / closing degree of an exhaust valve (not shown). When the degree of vacuum in the chamber 418 becomes stable, RF power is introduced from the RF power supply 424 to the bias rod 428 to generate plasma. In this manner, the hydrogen plasma treatment of the present invention is performed for a predetermined time. It is desirable to appropriately change the flow rate of the hydrogen gas, the flow rate of the silicon atom-containing gas, the RF power, the substrate temperature, and the like, depending on whether the hydrogen plasma processing is performed depending on the front state of the substrate or the state of the inner wall of the chamber. . The preferred form of variation of these parameters is to initially increase the hydrogen flow and decrease the hydrogen flow over time. As a form of the change in the flow rate of the silicon atom-containing gas, the flow rate of the silicon atom-containing gas is initially small and the flow rate of the silicon atom-containing gas is increased with time. A preferred form of change is that the RF power is initially high and then reduced over time.
[0045]
As described above, one pin structure is formed, and then the substrate holder holding the substrate on which the pin structure is formed is moved to the transfer chamber 402, and the pin structure is stacked by the operation procedure of depositing each layer of the pin. In the case of a triple cell, such an operation may be repeated once. In a photovoltaic element in which a plurality of pin structures are stacked, it is preferable that the i-type layers be stacked in such a manner that the band gap becomes narrower in order from the light incident side.
[0046]
In the above-described method for forming a photovoltaic element for performing a hydrogen plasma treatment according to the present invention, the gas cylinder may be replaced with a necessary gas cylinder as needed. In that case, it is preferable that the gas line be sufficiently heated and purged.
Next, the components of the photovoltaic element will be described in detail.
(substrate)
The material of the support preferably used in the present invention is preferably a material having little deformation and distortion at a temperature required at the time of forming a deposited film, having a desired strength, and having conductivity. A support that does not reduce the adhesion of the reflective layer or the reflection enhancing layer to the support even when the hydrogen plasma treatment of the present invention is performed after depositing the reflective layer or the reflection enhancing layer is preferable.
[0047]
Specifically, thin films of metals such as stainless steel, aluminum and its alloys, iron and its alloys, copper and its alloys and their composites, and metal thin films of different materials and / or SiO on their surfaces₂, Si₃N₄, Al₂O₃, AlN or other insulating thin film that has been subjected to surface coating by sputtering, vapor deposition, plating, or the like, or a heat-resistant resin sheet such as polyimide, polyamide, polyethylene terephthalate, or epoxy, or a glass fiber or carbon fiber , Boron fiber, metal fiber, etc., on the surface of which a metal alone or alloy, a transparent conductive oxide or the like is subjected to a conductive treatment by a method such as plating, vapor deposition, sputtering, or coating.
[0048]
The thickness of the support is preferably as thin as possible in consideration of cost, storage space, and the like, as long as the strength is such that the curved shape formed when the support is moved is maintained. . Specifically, the thickness is preferably from 0.01 mm to 5 mm, more preferably from 0.02 mm to 2 mm, and most preferably from 0.05 mm to 1 mm. Desired strength is easily obtained even when thin.
[0049]
The width of the support is not particularly limited and is determined by the size of the vacuum vessel and the like.
The length of the support is not particularly limited, and may be a length that can be wound into a roll, or may be a longer one that is made longer by welding or the like. Good.
[0050]
In the present invention, the support is heated and cooled in a short time, but it is not preferable that the temperature distribution spreads in the longitudinal direction of the support. In order to follow the heating and cooling, it is preferable that the heat conduction is large in the thickness direction.
To reduce the heat conduction of the support in the moving direction and increase it in the thickness direction, the thickness may be reduced. When the support is uniform, (heat conduction) × (thickness) is preferably 1 × 10^-1W / K or less, more preferably 0.5 × 10^-1It is desirable that it is not more than W / K.
[0051]
(Reflective layer)
Examples of the material for the reflective layer include metals such as Ag, Au, Pt, Ni, Cr, Cu, Al, Ti, Zn, Mo, and W, and alloys thereof. It is formed by vapor deposition, sputtering, or the like. Also, care must be taken that the formed metal thin film does not become a resistance component with respect to the output of the photovoltaic element, and the sheet resistance of the reflective layer is preferably 50Ω or less, more preferably 10Ω or less. Is desirable.
[0052]
When the support is light-transmitting and the photovoltaic element is irradiated with light from the light-transmitting support, it is preferable to form a light-transmitting conductive layer instead of the reflective layer. . As a light-transmitting conductive layer suitable for such a purpose, tin oxide, indium oxide, an alloy thereof, or the like is suitable. Further, it is preferable that these light-transmitting conductive layers are deposited to a thickness that satisfies the condition of antireflection. The sheet resistance of these translucent conductive layers is preferably 50Ω or less, more preferably 10Ω or less.
[0053]
(Reflection increasing layer)
The reflection increasing layer desirably has a light reflectance of 85% or more in order to efficiently absorb the reflected light from the substrate that has passed through the semiconductor layer into each semiconductor layer. The sheet resistance is desirably 100Ω or less so as not to become a resistance component with respect to the output of the power element. As a material having such characteristics, SnΟ₂, In₂O₃, ZnΟ, CdΟ, Cd₂SnO₄, ITO (In₂Ο₃+ SnO₂And the like. In the photovoltaic element, the reflection increasing layer is laminated in contact with the p-type layer or the n-type layer, and it is necessary to select a layer having good mutual adhesion. Further, it is preferable that the reflection enhancing layer is deposited to a thickness that meets the conditions for increasing the reflection. As a method for forming the reflection increasing layer, a resistance heating evaporation method, an electron beam heating evaporation method, a sputtering method, a spray method, or the like can be used, and is appropriately selected as desired.
[0054]
(I-type layer)
In particular, in a photovoltaic device using a group IV or group IV alloy amorphous semiconductor material, an i-type layer used for a pin junction is an important layer for generating and transporting carriers with respect to irradiation light. As the i-type layer, a slightly p-type or slightly n-type layer can also be used. The amorphous semiconductor material contains a hydrogen atom (H, D) or a halogen atom (X), which has an important function.
[0055]
Hydrogen atoms (H, D) or halogen atoms (X) contained in the i-type layer work to compensate for dangling bonds in the i-type layer, and the carrier mobility in the i-type layer. And product life. Further, it works to compensate for the interface state at each interface of the p-type layer / i-type layer and the n-type layer / i-type layer, and has the effect of improving the photovoltaic power, photocurrent and photoresponsiveness of the photovoltaic element. There is something. The optimum content of hydrogen atoms and / or halogen atoms contained in the i-type layer is 1 to 40 at%. In particular, those having a large content of hydrogen atoms and / or halogen atoms distributed on each interface side of the p-type layer / i-type layer and the n-type layer / i-type layer are mentioned as a preferable distribution form. The content of the hydrogen atom and / or the halogen atom in the above is preferably 1.1 to 2 times the content in the bulk as a preferable range. Further, it is preferable that the content of hydrogen atoms and / or halogen atoms is changed in accordance with the content of silicon atoms.
[0056]
When the photovoltaic device of the present invention has a plurality of pin structures, it is preferable to stack the i-type layers in order from the light incident side such that the band gap of the i-type layers becomes smaller. Amorphous silicon or amorphous silicon carbide is used as the i-type layer having a relatively wide band gap, and amorphous silicon germanium is used as the i-type semiconductor layer having a relatively narrow band gap. Amorphous silicon and amorphous silicon germanium are formed by a-Si: H, a-Si: F, a-Si: H: F, a-SiGe: H, a-Si: H, a-Si: F, depending on an element for capturing a dangling bond. It is described as SiGe: F, a-SiGe: H: F, or the like.
[0057]
When amorphous silicon germanium is used for the i-type layer, it is preferable to change the germanium content in the thickness direction of the i-type layer. In particular, it is a preferable distribution form of germanium that the germanium content continuously decreases in the direction of the n-type layer and / or the p-type layer. The distribution of germanium atoms in the layer thickness can be achieved by changing the flow ratio of the germanium-containing gas contained in the source gas. As a method of changing the content of germanium atoms in the i-type layer by the MW plasma CVD method, in addition to a method of changing a flow rate ratio of a germanium-containing gas, a method of changing a flow rate of a hydrogen gas which is a diluent gas of a source gas is used. This can be done in the same way. By increasing the amount of hydrogen dilution, the germanium content in the deposited film (i-type layer) can be increased.
[0058]
The hydrogen plasma treatment of the present invention particularly improves the electrical connection between a so-called graded band gap layer in which germanium atoms are continuously changed and a buffer layer in contact with the so-called graded band gap layer.
More specifically, for example, a pin junction i-type semiconductor layer suitable for the photovoltaic device of the present invention includes i-type hydrogenated amorphous silicon (a-Si: H). As characteristics, the optical band gap (Eg) is 1.60 eV to 1.85 eV, the hydrogen atom content (CH) is 1.0 to 25.0%, AM 1.5, 100 mW / cm.²Has a photoelectric conductivity (σp) under simulated sunlight irradiation of 1.0 × 10^-5S / cm or more, dark conductivity (σd) is 1.0 × 10^-9S / cm or less, inclination of Urbach tail by constant photocurrent method (CPM) is 55 meV or less, and localized level density is 10¹⁷/ Cm³The following are preferred.
[0059]
The semiconductor material amorphous silicon germanium constituting the i-type semiconductor layer having a relatively narrow band gap of the photovoltaic device of the present invention has an optical band gap (Eg) of 1.20 eV to 1. 60 eV, the content of hydrogen atoms (CH) is 1.0 to 25%, the slope of the Urbach tail by the constant photocurrent method (CPM) is 55 meV or less, and the localized level density is 10¹⁷cm³The following are preferred.
[0060]
The i-type layer suitable for the present invention is preferably deposited under the following conditions. The amorphous semiconductor layer is preferably deposited by RF, VHF or MW plasma CVD.
When the deposition is performed by the RF plasma CVD method, the substrate temperature is 100 to 350 ° C., the degree of vacuum in the deposition chamber is 0.05 to 10 Torr, and the RF frequency is 1 to 50 MHz. Particularly, the RF frequency is preferably 13.56 MHz. The RF power supplied into the deposition chamber is 0.01 to 5 W / cm.²Is a preferable range. The preferable range of the self-bias applied to the substrate by the RF power is 0 to 300.
[0061]
When the deposition is performed by the VHF plasma CVD method, the substrate temperature is 100 to 450 ° C., the degree of vacuum in the deposition chamber is 0.0001 to 1 Torr, and the frequency of VHF is 60 to 500 MHz. Particularly, the frequency of VHF is suitably 100 MHz. The VHF power input into the deposition chamber is 0.01 to 1 W / cm.³Is a preferable range. The preferable range of the self-bias applied to the substrate by the VHF power is 10 to 1000 V. In addition, the characteristics of the deposited amorphous film are improved by introducing DC or RF into the deposition chamber by overlapping with VHF or separately providing a bias rod. When a DC bias is introduced using a bias bar, it is preferred that the bias bar be positive. When the DC bias is introduced to the substrate side, it is preferable to introduce the DC bias so that the substrate side becomes a negative electrode. When introducing an RF bias, it is preferable to make the area of the electrode into which RF is introduced smaller than the substrate area.
[0062]
When the deposition is performed by the MW plasma CVD method, the substrate temperature is 100 to 450 ° C., the degree of vacuum in the deposition chamber is 0.0001 to 0.05 Torr, and the frequency of the MW is 501 MHz to 10 GHz. In particular, the MW frequency is suitably 2.45 GHz. The MW power input into the deposition chamber is 0.01 to 1 W / cm.³Is a preferable range. MW power is optimally introduced into the deposition chamber via a waveguide. Also, in addition to the MW, a bias rod is separately provided to introduce DC or RF into the deposition chamber, thereby improving the characteristics of the deposited amorphous film. When a DC bias is introduced using a bias bar, it is preferred that the bias bar be positive. When the DC bias is introduced to the substrate side, it is preferable to introduce the DC bias so that the substrate side becomes a negative electrode. When introducing an RF bias, it is preferable to make the area of the electrode into which RF is introduced smaller than the substrate area.
[0063]
For the deposition of the i-type layer suitable for the plasma treatment of the present invention, SiH₄, Si₂H₆, SiF₄, SiF₂H₂And the like. To widen the band gap, it is preferable to add a gas containing carbon, nitrogen or oxygen. It is preferable that carbon-, nitrogen-, or oxygen-containing gas is contained more in the vicinity of the p-type layer and / or the n-type layer than in the i-type layer. By doing so, the open-circuit voltage can be improved without impairing the traveling properties of charges in the i-type layer. As the carbon-containing gas, C_nH_{2n + 2}, C_nH_2nAnd C₂H₂Etc. are suitable. As a nitrogen-containing gas, N₂, NO, N₂0, NO₂, NH₃Etc. are suitable. Oxygen-containing gases include O₂, CO₂, O₃Etc. are suitable. Also, a plurality of these gases may be introduced in combination. A suitable amount of the source gas for increasing the band gap is 0.1 to 50%.
[0064]
Further, the characteristics of the i-type layer are improved by adding an element of Group III and / or Group V of the periodic table. As the Group III element of the periodic table, B, Al, Ga and the like are suitable. Especially when B is added, B₂H₆, BF₃It is preferable to use a gas such as the above. N, P, As, etc. are suitable as Group V elements of the periodic table. Especially when P is added, PH₃Are suitable. The suitable amount of the Group III and / or Group V element of the periodic table added to the i-type layer is 0.1 to 1000 ppm.
[0065]
By providing an n / i buffer layer or a p / i buffer layer for the i-type layer, the characteristics of the photovoltaic element are improved. As the buffer layer, a semiconductor layer similar to the i-type layer can be used, and it is particularly preferable to deposit the buffer layer at a lower deposition rate than the i-type layer. As the buffer layer, a semiconductor having a wider band gap than the i-type layer is suitable. Preferably, the band gap is smoothly continuous from the i-type layer to the buffer layer. As a method for continuously changing the band gap in the buffer layer, the band gap can be narrowed by increasing the content of germanium atoms contained in a silicon-based non-single-crystal semiconductor. On the other hand, the band gap can be continuously increased by increasing the content of carbon atoms, oxygen atoms, and / or nitrogen atoms contained in a silicon-based non-single-crystal semiconductor. It is a preferable range that the ratio of the narrowest band gap to the widest band gap is 1.01 to 1.5.
[0066]
When an element of Group III or / and Group V of the periodic table is added to the buffer layer, a Group III element of the periodic table is added to the n / i buffer layer and the p / i buffer layer is added to the p / i buffer layer. Is preferably a group V element of the periodic table. By doing so, it is possible to prevent a decrease in characteristics due to diffusion of impurities from the n-type layer and / or the p-type layer into the i-type layer.
[0067]
(N-type layer, p-type layer)
The p-type layer or the n-type layer is also an important layer that affects the characteristics of the photovoltaic device of the present invention. As an amorphous material (denoted as a-) of a p-type layer or an n-type layer (it goes without saying that a microcrystalline material (denoted as μc-) is also included in the range of an amorphous material). a-Si: H, a-Si: HX, a-SiC: H, a-SiC: HX, a-SiGe: H, a-SiGeC: H, a-SiO: H, a-SiN: H, a- SiON: HX, a-SiOCN: HX, μc-Si: H, μc-SiC: H, μc-Si: HX, μc-SiC: HX, μc-SiGe: H, μc-SiO: H, μc-SiGeC: H, μc-SiN: H, μc-SiON: HX, μc-SiOCN: HX, etc., p-type valence electron controlling agents (Group III atoms B, Al, Ga, In, TI) in the periodic table and n-type Valence electron controlling agents (Group V group atoms P, As, Sb, Bi) were added at a high concentration. Materials include polycrystalline materials (denoted as poly-), for example, poly-Si: H, poly-Si: HX, poly-SiC: H, poly-SiC: HX, poly-SiGe: H, poly -Si, poly-SiC, poly-SiGe, etc., p-type valence electron control agents (Group III atoms B. Al, Ga, In, Tl) and n-type valence electron control agents (periodic table) Materials to which Group V atoms (P, As, Sb, Bi) are added at a high concentration may be mentioned.
[0068]
In particular, as the p-type layer or the n-type layer on the light incident side, a crystalline semiconductor layer with little light absorption or an amorphous semiconductor layer with a wide band gap is suitable.
The optimal amount of the group III atom in the periodic table to be added to the p-type layer and the group V atom to be added to the n-type layer is 0.1 to 50 at%.
Hydrogen atoms (H, D) or halogen atoms contained in the p-type layer or the n-type layer work to compensate for dangling bonds of the p-type layer or the n-type layer, and doping efficiency of the p-type layer or the n-type layer. Is to improve. The optimum amount of hydrogen atoms or halogen atoms added to the p-type layer or the n-type layer is 0.1 to 40 at%. In particular, when the p-type layer or the n-type layer is crystalline, the optimal amount of hydrogen atoms or halogen atoms is 0.1 to 8 at%. Further, a preferable distribution form is one in which the content of hydrogen atoms and / or halogen atoms is large at each interface side of the p-type layer / i-type layer and the n-type layer / i-type layer. The content of the hydrogen atom and / or the halogen atom is preferably in a range of 1.1 to 2 times the content in the bulk. As described above, by increasing the content of hydrogen atoms or halogen atoms near each interface between the p-type layer / i-type layer and the n-type layer / i-type layer, the defect level and mechanical strain near the interface are reduced. Accordingly, the photovoltaic power and the photocurrent of the photovoltaic device of the present invention can be increased.
[0069]
The p-type layer and the n-type layer of the photovoltaic element preferably have an activation energy of 0.2 eV or less, and most preferably have an activation energy of 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. Further, the thickness of the p-type layer and the n-type layer is preferably 1 to 50 nm, and most preferably 3 to 10 nm.
In order to form a group IV and group IV alloy-based amorphous semiconductor layer suitable as a semiconductor layer of the photovoltaic device of the present invention, the most preferable manufacturing method is a microwave plasma CVD method, and then the most preferable manufacturing method. The method is an RF plasma CVD method.
[0070]
In the microwave plasma CVD method, a material gas such as a raw material gas or a dilution gas is introduced into a deposition chamber, and while the inside pressure of the deposition chamber is kept constant while being evacuated by a vacuum pump, a microwave oscillated by a microwave power supply is used. Guided by a waveguide, introduced into the deposition chamber through a dielectric window (alumina ceramics or the like), a plasma of a material gas is generated and decomposed, and a desired deposited film is formed on a substrate disposed in the deposition chamber. This is a method for forming a deposited film that can be applied to a photovoltaic device under a wide range of deposition conditions.
[0071]
Examples of the source gas suitable for depositing the group IV and group IV alloy-based amorphous semiconductor layers suitable for the photovoltaic device of the present invention include a gasizable compound containing silicon atoms and a gas containing germanium atoms. Compounds which can be converted to gas, compounds which can be gasified containing carbon atoms, compounds which can be pre-gasified containing nitrogen atoms, compounds which can be gasified containing oxygen atoms, and mixed gas of these compounds can be prepared.
[0072]
Specific examples of the gasizable compound containing a silicon atom include a chain or cyclic silane compound.₄, Si₂H₆, SiF₄, SiFH₃, SiF₂H₂, SiF₃H, Si₃H₈, SiD₄, SiHD₃, SiH₂D₂, SiH₃D, SiFD₃, SiF₂D₂, SiD₃H, Si₂D₃H₃, (SiF₂)₅, (SiF₂)₆, (SiF₂)₄, Si₂F₆, Si₃F₈, Si₂H₂F₄, Si₂H₃F₃, SiCl₄, (SiCl₂)₅, SiBr₄, (SiBr₂)₅, Si₂Cl₆, SiHCl₃, SiH₂Br₂, SiH₂Cl₂, Si₂Cl₃F₃And those which can be easily gasified in a gas state.
[0073]
Specifically, a gasizable compound containing a germanium atom is GeH₄, GeD₄, GeF₄, GeFH₃, GeF₂H₂, GeF₃H, GeHD₃, GeH₂D₂, GeH₃D, Ge₂H₆, Ge₂D₆And the like.
Specific examples of the gasizable compound containing a carbon atom include CH₄, CD₄, C_nH_{2n + 2}(N is an integer), C_nH_2n(N is an integer), C₂H₂, C₆H₆, CO₂, CO and the like.
[0074]
N as a nitrogen-containing gas₂, NH₃, ND₃, NO, NO₂, N₂O.
The oxygen-containing gas is O₂, CO, CO₂, NO, NO₂, N₂O, CH₃CH₂OH, CH₃OH is fisted.
In addition, as a substance introduced into the p-type layer or the n-type layer for controlling valence electrons, there may be mentioned a Group III element and a Group V atom of the periodic table.
[0075]
Effectively used as a starting material for introducing a group III atom, specifically, for introducing a boron atom, B₂H₆, B₄H₁₀, B₅H₉, B₅H₁₁, B₆H₁₀, B₆H₁₂, B₆H₁₄Such as hydrogenated boron, BF₃, BCl₃And the like. In addition, AlCl₃, GaCl₃, InCl₃, TlCl₃And the like. Especially B₂H₆, BF₃Is suitable
Effectively used as a starting material for introducing a group V atom is, specifically, PH for introducing a phosphorus atom.₃, P₂H₄Phosphorus hydride, PH₄I, PF₃, PF₅, PCl₃, PCl₅, PBr₃, PBr₅, PI₃And the like. In addition, AsH₃, AsF₃, AsCl₃, AsBr₃, AsF₅, SbH₃, SbF₃, SbF₅, SbCl₃, SbCl₅, BiH₃, BiCl₃, BiBr₃And the like. Especially PH₃, PF₃Is suitable.
[0076]
Further, the compound capable of being gasified is H₂, He, Ne, Ar, Xe, Kr, etc., may be appropriately diluted and introduced into the deposition chamber. In particular, when depositing a layer having a small light absorption or a wide band gap such as a microcrystalline semiconductor or a-SiC: H, dilute the source gas 2 to 100 times with hydrogen gas, and compare the microwave power or RF power. It is preferable to introduce extremely high power.
[0077]
(Transparent electrode)
The transparent electrode desirably has a light transmittance of 85% or more to efficiently absorb light from the sun, a white fluorescent lamp, or the like into each semiconductor layer. The sheet resistance is desirably 100Ω or less so as not to become a resistance component with respect to the output. As a material having such characteristics, SnO 2₂, In₂O₃, ZnO, CdO, Cd₂SnO₄, ITO (In₂O₃+ SnO₂), And a metal thin film formed of a metal such as Au, Al, Cu, etc. in a very thin and translucent state. The transparent electrode is laminated on the p-type layer or the n-type layer in the photovoltaic element, forms the photovoltaic element on the translucent support, and irradiates light from the translucent support side. Is laminated on a support, it is necessary to select one having good mutual adhesion. Further, it is preferable that the transparent electrode is deposited to a thickness that meets the antireflection conditions. As a method for manufacturing the transparent electrode, a resistance heating evaporation method, an electron beam heating evaporation method, a sputtering method, a spray method, or the like can be used, and is appropriately selected as desired.
[0078]
(Collecting electrode)
The current collecting electrode of the photovoltaic element which has been subjected to the hydrogen plasma treatment of the present invention may be formed by screen printing a silver paste or using a mask of Cr, Ag, Au, Cu, Ni, Μo, Al, or the like. And may be formed by vacuum evaporation. Alternatively, carbon or Ag powder may be attached to a metal wire such as Cu, Au, Ag, or Al together with a resin and attached to the surface of the photovoltaic element to form a current collecting electrode.
[0079]
When manufacturing a photovoltaic device having a desired output voltage and output current using the photovoltaic device of the present invention, the photovoltaic devices of the present invention are connected in series or in parallel, and the front and rear surfaces are connected. , A protective layer is formed, and an output output electrode and the like are attached. When the photovoltaic elements of the present invention are connected in series, a diode for preventing backflow may be incorporated.
[0080]
【Example】
Hereinafter, a method for forming a photovoltaic element of the present invention will be described in detail for a solar cell made of a non-single-crystal silicon-based semiconductor material, but the present invention is not limited thereto.
(Example 1)
The tandem solar cell of FIG. 1 was manufactured using the deposition apparatus shown in FIG.
First, a substrate was manufactured. 0.5mm thick, 50x50mm²The stainless steel support (200) was ultrasonically washed with acetone and isopropanol and dried with hot air.
[0081]
An Ag light reflecting layer (201) having a thickness of 0.3 μm on a surface of a stainless steel support (200) at room temperature using a sputtering method and a ZnO reflection increasing layer having a thickness of 1.0 μm at 350 ° C. (202) was formed, and the production of the substrate was completed.
Next, each semiconductor layer was formed on the reflection increasing layer using the deposition apparatus 400. The deposition apparatus 400 can perform both the MWPCVD method and the RFPCVD method.
[0082]
A source gas cylinder (not shown) is connected to the deposition apparatus through a gas introduction pipe. All raw material gas cylinders have been purified to ultra-high purity.₄Gas cylinder, SiF₄Gas cylinder, CH₄Gas cylinder, GeH₄Gas cylinder, GeF₄Gas cylinder, Si₂H₆Gas cylinder, PH₃/ H₂(Dilution: 1000 ppm) Gas cylinder, B₂H₆/ H₂(Dilution: 2000 ppm, 1%, 10%) Gas cylinder, BF₃/ H₂(Dilution 2000ppm, 1%, 10%) Gas cylinder, H₂Gas cylinder, He gas cylinder, SiCl₂H₂Gas cylinder, SiH₄/ H₂(Dilution: 1000 ppm) Gas was connected.
[0083]
Next, the substrate 490 on which the reflection layer 201 and the reflection enhancement layer 202 are formed is arranged on the substrate transport rail 413 in the load chamber 401, and the pressure in the load chamber 401 is reduced to about 1 by a vacuum exhaust pump (not shown). × 10^-5The system was evacuated to Torr. Next, the gate valve 406 was opened and transferred into the transfer chamber 402 and the deposition chamber 417 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 410 and heated, and the pressure inside the deposition chamber 417 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0084]
After the preparation for film formation was completed as described above, an RF n-type layer 203 made of μc-Si was formed.
To form an RF n-type layer made of μc-Si, H₂Gas is introduced into the deposition chamber 417 through the gas introduction pipe 429, and H₂The valves 441, 431, and 430 were opened so that the gas flow rate became 300 sccm, and adjustment was performed by the mass flow controller 436. The pressure in the deposition chamber 417 was adjusted to 1.1 Torr by a conductance valve (not shown). The base heating heater 410 is set so that the temperature of the substrate 490 becomes 380 ° C., and when the substrate temperature is stabilized, the SiH₄Gas, PH₃/ H₂The gas was introduced into the deposition chamber 417 through the gas introduction pipe 429 by operating the valves 443, 433, 444, and 434. At this time, SiH₄Gas flow rate 1.5 sccm, H₂Gas flow rate 100 sccm, PH₃/ H₂The mass flow controllers 438, 436, and 439 adjusted the gas flow rate to 200 sccm, and the pressure in the deposition chamber 417 was adjusted to 1.1 Torr. The power of the RF power supply 422 is set to 0.05 W / cm.³RF power is introduced into the plasma forming cup 420 to cause glow discharge to start forming an RF n-type layer on the substrate. Then, the glow discharge was stopped, and the formation of the RF n-type layer 203 was completed. SiH into the deposition chamber 417₄Gas, PH₃/ H₂The flow of H into the deposition chamber for 4 minutes.₂After continuing to flow gas, H₂Is stopped, and 1 × 10^-5Evacuated to Torr.
[0085]
Next, an n / i buffer layer 251 made of a-Si was formed by RFPCVD. First, the gate valve 407 was opened and the substrate 490 was transferred into the transfer chamber 403 and the i-type layer deposition chamber 418 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 411 and heated, and the pressure in the i-type layer deposition chamber 418 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0086]
In order to manufacture the n / i buffer layer 251, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 360 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, and 453 are set. Open gradually, Si₂H₆Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 2.5 sccm, H₂The mass flow controllers 459, 458 adjusted the gas flow rate to 100 sccm. The opening of a conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 0.7 Torr. Next, the RF power supply 424 is set to 0.07 W / cm³Is applied to the bias rod 428 to generate a glow discharge, and the shutter 427 is opened to start forming an n / i buffer layer on the RF n-type layer, thereby forming an n / i buffer layer having a layer thickness of 10 nm. Then, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the fabrication of the n / i buffer layer 251 was completed. The valves 464 and 454 are closed to allow the Si to enter the i-type layer deposition chamber 418.₂H₆Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0087]
Next, an MWi-type layer 204 made of a-SiGe was formed by MWPCVD. To manufacture the MWi-type layer, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 380 ° C., and when the substrate is sufficiently heated, the valves 461, 451, 450, 462, 452, 463, 453 are formed. Gradually open the SiH₄Gas, GeH₄Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, SiH₄Gas flow rate 37 sccm, GeH₄Gas flow rate 38 sccm, H₂The mass flow controllers 456, 457, and 458 adjusted the gas flow rate to 165 sccm. The opening of the conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 5 mTorr. Next, a high frequency (hereinafter abbreviated as “RF”) power supply 424 is set to 0.6 W / cm.³And applied to the bias bar 428. Thereafter, the power of the MW power supply (not shown) is increased to 0.28 W / cm.³MW power is introduced into the i-type layer deposition chamber 418 through the waveguide 426 and the microwave introduction window 425 to generate glow discharge, and the shutter 427 is opened to open the MWi type on the n / i buffer layer. When the production of the layer was started and the i-type layer having a thickness of 0.15 μm was produced, the MW glow discharge was stopped, the output of the bias power supply 424 was turned off, and the production of the MWi-type layer 204 was completed. The valves 451 and 452 are closed and the SiH into the i-type layer deposition chamber 418₄Gas, GeH₄Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0088]
Next, ap / i buffer layer 261 made of a-Si was formed by RFPCVD.
In order to form the p / i buffer layer 261, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, and 453 are set. Open gradually, Si₂H₆Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 3 sccm, H₂The mass flow controllers 459 and 458 adjusted the gas flow rate to 80 sccm. The opening of a conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 0.7 Torr. Next, the RF power supply 424 is set to 0.07 W / cm³Is applied to the bias rod 428 to generate glow discharge, and by opening the shutter 427, the production of the p / i buffer layer 261 is started on the MWi-type layer. After the fabrication, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the fabrication of the p / i buffer layer 261 was completed. The valves 464 and 454 are closed to allow the Si to enter the i-type layer deposition chamber 418.₂H₆Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0089]
Next, in order to form the RF p-type layer 205 made of a-SiC, the gate valve 408 is opened into the transfer chamber 404 and the p-type layer deposition chamber 419 that have been evacuated in advance by a vacuum pump (not shown). 490 was conveyed. The back surface of the substrate 490 is brought into close contact with the substrate heating heater 412 and heated, and the pressure in the p-type layer deposition chamber 419 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0090]
The substrate heating heater 412 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate temperature becomes stable, H₂Gas, SiH₄/ H₂Gas, B₂H₆/ H₂Gas, CH₄The gas was introduced into the deposition chamber 419 through the gas introduction pipe 469 by operating the valves 481, 471, 470, 482, 472, 483, 473, 484, and 474. At this time, H₂Gas flow rate 60scm, SiH₄/ H₂Gas flow rate 0.5 sccm, B₂H₆/ H₂(Dilution: 1%) Gas flow rate is 1 sccm, CH₄The mass flow controllers 476, 477, 478, and 479 adjusted the gas flow rate to 0.3 sccm, and the opening of a conductance valve (not shown) was adjusted so that the pressure in the deposition chamber 419 became 1.7 Torr. The power of the RF power supply 423 is set to 0.07 W / cm³RF power is introduced into the plasma forming cup 421 to generate glow discharge, start forming an RFp-type layer on the p / i buffer layer, and form an RFp-type layer having a layer thickness of 10 nm. The power was turned off, the glow discharge was stopped, and the formation of the RFp type layer 205 was completed. Close the valves 472, 482, 473, 483, 474, 484 and place the SiH into the p-type layer deposition chamber 419.₄/ H₂Gas, B₂H₆/ H₂Gas, CH₄Stop the flow of gas and introduce H into the p-type layer deposition chamber 419 for 3 minutes.₂After the gas continues to flow, the valves 471, 481, and 470 are closed and H₂Is stopped, and the inside of the p-type layer deposition chamber 419 and the gas pipe is^-5Evacuated to Torr.
[0091]
Next, hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed under the conditions shown in Table 1 (1). In order to carry out the hydrogen plasma treatment containing a trace amount of a group III element according to the present invention, B is used as a group III element-containing gas.₂H₆/ H₂(Dilution: 1%) SiH as a gas containing silicon atoms₄Gas, H₂A gas is introduced into the deposition chamber 419 through a gas introduction pipe 469, and H₂The valves 481, 471, and 470 were opened so that the gas flow rate became 1200 sccm, and adjustment was performed by the mass flow controller 476. Group III element-containing gas B₂H₆Gas is all H₂The valves 483 and 473 were opened so that the gas flow rate became 0.3%, and the mass flow controller 478 adjusted the flow rate. The gas containing silicon atoms is SiH₄Is all H₂A valve (not shown) was opened to adjust the gas flow rate to 0.01% with a mass flow controller (not shown). The conductance valve (not shown) was adjusted so that the pressure in the deposition chamber 419 became 0.7 Torr. The substrate heating heater 412 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate temperature is stabilized, the power of the RF power supply 423 is reduced to 0.05 W / cm.³, And RF was introduced into the plasma forming cup 421 to generate glow discharge, and the hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed for 3 minutes. Thereafter, the RF power is turned off to stop the glow discharge, and the B gas is introduced into the deposition chamber 419.₂H₆/ H₂, SiH₄Stop the flow of gas and enter H into the deposition chamber 419 for 3 minutes.₂After continuing to flow gas, H₂The flow of gas was stopped, and the inside of the deposition chamber 419 and the inside of the gas pipe were^-5Evacuated to Torr.
[0092]
Next, in order to form the RF n-type layer 206 made of μc-Si, the gate valve 408 is introduced into the transfer chamber 402 and the deposition chamber 417 through the transfer chamber 403 previously evacuated by a vacuum pump (not shown). 407 was opened and transported. The back surface of the substrate 490 is brought into close contact with the substrate heating heater 410 and heated, and the pressure inside the deposition chamber 417 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0093]
To form an RF n-type layer made of μc-Si, H₂Gas is introduced into the deposition chamber 417 through the gas introduction pipe 429, and H₂The valves 441, 431, and 430 were opened so that the gas flow rate became 200 sccm, and adjustment was performed by the mass flow controller 436. The pressure in the deposition chamber 417 was adjusted to 1.1 Torr by a conductance valve (not shown). The substrate heating heater 410 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate temperature is stabilized, the SiH₄Gas, PH₃/ H₂The gas was introduced into the deposition chamber 417 through the gas introduction pipe 429 by operating the valves 443, 433, 444, and 434. At this time, SiH₄Gas flow rate 1.5 sccm, H₂Gas flow rate 80 sccm, PH₃/ H₂The mass flow controllers 438, 436, and 439 adjusted the gas flow rate to 250 sccm, and the pressure in the deposition chamber 417 was adjusted to 1.1 Torr. The power of the RF power supply 422 is set to 0.05 W / cm.³RF power is introduced into the plasma forming cup 420 to cause glow discharge to start the formation of the RF n-type layer on the RF p-type layer. When the RF n-type layer having a thickness of 10 nm is formed, the RF power supply is turned on. Then, the glow discharge was stopped, and the formation of the RF n-type layer 206 was completed. SiH into the deposition chamber 417₄Gas, PH₃/ H₂The flow of H into the deposition chamber for 2 minutes.₂After continuing to flow gas, H₂Is stopped, and 1 × 10^-5Evacuated to Torr.
[0094]
Next, an n / i buffer layer 252 made of a-SiC was formed by RFPCVD. First, the gate valve 407 was opened and the substrate 490 was transferred into the transfer chamber 403 and the i-type layer deposition chamber 418 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 411 and heated, and the pressure in the i-type layer deposition chamber 418 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0095]
To form the n / i buffer layer 252, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, 453, 465 and 455 are gradually opened, and Si₂H₆Gas, H₂Gas, CH₄The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 0.4 sccm, H₂Gas flow rate 90 sccm, CH₄The mass flow controllers 459, 458, and 460 adjusted the gas flow rate to 0.2 sccm.
[0096]
The opening of a conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 1.0 Torr. Next, the RF power supply 424 is set to 0.06 W / cm.³Is applied to the bias rod 428 to generate a glow discharge, and the shutter 427 is opened to start forming an n / i buffer layer on the RF n-type layer, thereby forming an n / i buffer layer having a layer thickness of 10 nm. Then, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the fabrication of the n / i buffer layer 252 was completed. The valves 464, 454, 465, 455 are closed and the Si into the i-type layer deposition chamber 418 is₂H₆Gas, CH₄Stop the flow of gas and place H in the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0097]
Next, an RFi-type layer 207 made of a-Si was formed by an RFPCVD method. To manufacture the RFi-type layer, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 200 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, and 453 are gradually opened. And Si₂H₆Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 3 sccm, H₂The mass flow controllers 459 and 458 adjusted the gas flow rate to 85 sccm. The opening of a conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 0.5 Torr. Next, the RF power supply 424 is set to 0.07 W / cm³Is applied to the bias rod 428 to generate a glow discharge, and by opening the shutter 427, the production of the RFi-type layer is started on the n / i buffer layer 252 to produce an i-type layer having a layer thickness of 110 nm. The RF glow discharge was stopped, the output of the RF power source 424 was turned off, and the fabrication of the RFi-type layer 207 was completed. The valves 464 and 454 are closed to allow the Si to enter the i-type layer deposition chamber 418.₂H₆Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0098]
Next, ap / i buffer layer 262 made of a-Sic was formed by RFPCVD. To form the p / i buffer layer 262, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 200 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, 453, 465 and 455 are gradually opened, and Si₂H₆Gas, H₂Gas, CH₄The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 0.4 sccm, H₂Gas flow rate 65 sccm, CH₄The mass flow controllers 459, 458, and 460 adjusted the gas flow rate to 0.3 sccm. The opening of the conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 1.1 Torr. Next, the RF power supply 424 is set to 0.06 W / cm.³Is applied to the bias rod 428 to generate a glow discharge, and the shutter 427 is opened to start forming a p / i buffer layer on the RFi-type layer, thereby forming a 15 nm thick p / i buffer layer. Then, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the production of the p / i buffer layer 262 was completed. The valves 464, 454, 465, 455 are closed and the Si into the i-type layer deposition chamber 418 is₂H₆Gas, CH₄Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0099]
Next, in order to form the RF p-type layer 208 made of a-SiC, the gate valve 408 is opened into the transfer chamber 404 and the p-type layer deposition chamber 419 evacuated by a vacuum pump (not shown) in advance. 490 was conveyed. The back surface of the substrate 490 is brought into close contact with the substrate heating heater 412 and heated, and the pressure in the p-type layer deposition chamber 419 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0100]
The substrate heating heater 412 is set so that the temperature of the substrate 490 becomes 170 ° C.₂Gas, SiH₄/ H₂Gas, B₂H₆/ H₂Gas (dilution: 1%), CH₄The gas was introduced into the deposition chamber 419 through the gas introduction pipe 469 by operating the valves 481, 471, 470, 482, 472, 483, 473, 484, and 474. At this time, H₂Gas flow rate 70scm, SiH₄/ H₂Gas flow rate 0.5 sccm, B₂H₆/ H₂(Dilution: 1%) Gas flow rate is 1 sccm, CH₄The mass flow controllers 476, 477, 478, and 479 adjusted the gas flow rate to 0.3 sccm, and the opening of a conductance valve (not shown) was adjusted so that the pressure in the deposition chamber 419 became 1.7 Torr. The power of the RF power supply 423 is set to 0.07 W / cm³, And RF power is introduced into the plasma forming cup 421 to generate glow discharge, start forming an RFp-type layer on the p / i buffer layer 262, and form a 10-nm-thick RFp-type layer. The RF power was turned off to stop glow discharge, and the formation of the RF p-type layer 208 was completed. Close the valves 472, 482, 473, 483, 474, 484 and place the SiH into the p-type layer deposition chamber 419.₄/ H₂Gas, B₂H₆/ H₂Gas, CH₄Stop the flow of gas and introduce H into the p-type layer deposition chamber 419 for 2 minutes.₂After the gas continues to flow, the valves 471, 481, and 470 are closed and H₂Is stopped, and the inside of the p-type layer deposition chamber 419 and the gas^-5Evacuated to Torr.
[0101]
Next, the gate valve 409 was opened into the unload chamber 405 previously evacuated by the evacuation pump (not shown), the substrate 490 was transported, and the unload chamber 405 was leaked by opening the leak valve (not shown).
Next, as the transparent conductive layer 212, ITO having a thickness of 70 nm was vacuum-deposited on the RFp type layer 205 by a vacuum deposition method.
[0102]
Next, a mask having a comb-shaped hole was placed on the transparent conductive layer 212, and a comb-shaped current collecting electrode 213 made of Cr (40 nm) / Ag (1000 nm) / Cr (40 nm) was vacuum-deposited by a vacuum deposition method.
Thus, the production of the solar cell has been completed. This solar cell will be referred to as (SC Ex. 1), and the hydrogen plasma treatment conditions of the present invention containing a small amount of group III element, RFn-type layer, RFn / i buffer layer, MWi-type layer, RFp / i buffer layer, and RFp-type The conditions for forming the layers are shown in Tables 1 (1) and 1 (2).
[0103]
<Comparative Example 1>
A solar cell (SC ratio: 1) was produced under the same conditions as in Example 1 except that the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was not performed.
Eight solar cells (SC Ex. 1) and (SC ratio 1) were manufactured, each having eight photoelectric conversion efficiencies (photovoltaic power / incident optical power), vibration deterioration, light deterioration, and high temperature and high humidity when bias voltage was applied. Vibration degradation and light degradation in the environment were measured.
[0104]
The initial photoelectric conversion efficiency was measured using an AM1.5 (100 mW / cm²) It is obtained by installing under light irradiation and measuring VI characteristics. As a result of the measurement, the fill factor (FF), series resistance (Rs), and characteristic unevenness of the initial photoelectric conversion efficiency of (SC Ex. 1) with respect to (SC ratio 1) were as follows.

Vibration degradation was measured by placing a solar cell whose initial photoelectric conversion efficiency was measured in advance in a dark place with a humidity of 55% and a temperature of 26 ° C., and applying a vibration with a vibration frequency of 60 Hz and an amplitude of 0.1 mm for 500 hours. AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after vibration degradation test / initial photoelectric conversion efficiency) was used.
[0105]
The photodegradation was measured by placing a solar cell, whose initial photoelectric conversion efficiency was measured in advance, in an environment with a humidity of 55% and a temperature of 26 ° C., and an AM of 1.5 (100 mW / cm).²) After irradiation with light for 500 hours, AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after light degradation test / initial photoelectric conversion efficiency) was used. As a result of the measurement, the rate of decrease in photoelectric conversion efficiency after light deterioration (SC ratio 1) and the rate of decrease in photoelectric conversion efficiency after vibration deterioration with respect to (SC actual 1) were as follows.
[0106]

Vibration degradation and light degradation in a high temperature and high humidity environment at the time of bias application were measured. Two solar cells whose initial photoelectric conversion efficiencies were measured in advance were placed in a dark place at a humidity of 92% and a temperature of 86 ° C., and 0.72 V was applied as a forward bias voltage. The above-mentioned vibration was applied to one of the solar cells to measure the vibration degradation, and the other solar cell was irradiated with AM1.5 light to measure the light degradation. As a result of the measurement, the rate of decrease in photoelectric conversion efficiency after vibration degradation of (SC ratio 1) and the rate of decrease in photoelectric conversion efficiency after light degradation of (SC ratio 1) with respect to (SC actual 1) were as follows.
[0107]

The state of delamination was observed using an optical microscope. In (SC Ex. 1), no delamination was observed, but in (SC ratio 1), delamination was slightly observed.
As described above, the solar cell (SC Ex. 1) of the present invention has a better fill factor, series resistance, characteristic unevenness, photodegradation characteristic, adhesion, and so on than the conventional solar cell (SC ratio 1) in the photoelectric conversion efficiency of the solar cell. It was found that it had more excellent properties in durability.
[0108]
(Example 2)
The tandem solar cell of FIG. 1 was manufactured using the deposition apparatus shown in FIG.
The base slope 490 provided with the reflection layer 201 and the reflection enhancement layer 202 prepared by the same method as in the first embodiment is arranged on the substrate transport rail 413 in the load chamber 401, and is operated by a vacuum exhaust pump (not shown). The pressure in the load chamber 401 is about 1 × 10^-5The system was evacuated to Torr.
[0109]
Next, the gate valve 406 was opened and transferred into the transfer chamber 402 and the deposition chamber 417 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 410 and heated, and the pressure inside the deposition chamber 417 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0110]
After the preparation for film formation was completed as described above, an RF n-type layer 203 made of μc-Si was formed.
To form an RF n-type layer made of μc-Si, H₂Gas is introduced into the deposition chamber 417 through the gas introduction pipe 429, and H₂The valves 441, 431, and 430 were opened so that the gas flow rate became 300 sccm, and adjustment was performed by the mass flow controller 436. The pressure in the deposition chamber 417 was adjusted to 1.1 Torr by a conductance valve (not shown). The base heating heater 410 is set so that the temperature of the substrate 490 becomes 380 ° C., and when the substrate temperature is stabilized, the SiH₄Gas, PH₃/ H₂The gas was introduced into the deposition chamber 417 through the gas introduction pipe 429 by operating the valves 443, 433, 444, and 434. At this time, SiH₄Gas flow rate 1.2 sccm, H₂Gas flow rate 90 sccm, PH₃/ H₂The mass flow controllers 438, 436, and 439 adjusted the gas flow rate to 200 sccm, and the pressure in the deposition chamber 417 was adjusted to 1.1 Torr. The power of the RF power supply 422 is set to 0.06 W / cm³RF power is introduced into the plasma forming cup 420 to cause glow discharge to start forming an RF n-type layer on the substrate. Then, the glow discharge was stopped, and the formation of the RF n-type layer 203 was completed. SiH into the deposition chamber 417₄Gas, PH₃/ H₂The flow of H into the deposition chamber for 4 minutes.₂After continuing to flow gas, H₂Is stopped, and 1 × 10^-5Evacuated to Torr.
[0111]
Next, an n / i buffer layer 251 made of a-Si was formed by RFPCVD. First, the gate valve 407 was opened and the substrate 490 was transferred into the transfer chamber 403 and the i-type layer deposition chamber 418 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 411 and heated, and the pressure in the i-type layer deposition chamber 418 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0112]
In order to manufacture the n / i buffer layer 251, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 360 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, and 453 are set. Open gradually, Si₂H₆Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 2.5 sccm, H₂The mass flow controllers 459, 458 adjusted the gas flow rate to 100 sccm. The opening of the conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 0.8 Torr. Next, the RF power supply 424 was set to 0.08 W / cm³Is applied to the bias rod 428 to generate a glow discharge, and the shutter 427 is opened to start forming an n / i buffer layer on the RF n-type layer, thereby forming an n / i buffer layer having a layer thickness of 10 nm. Then, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the fabrication of the n / i buffer layer 251 was completed. The valves 464 and 454 are closed to allow the Si to enter the i-type layer deposition chamber 418.₂H₆Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0113]
Next, an MWi-type layer 204 made of a-SiGe was formed by MWPCVD. To manufacture the MWi-type layer, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 380 ° C., and when the substrate is sufficiently heated, the valves 461, 451, 450, 462, 452, 463, 453 are formed. Gradually open the SiH₄Gas, GeH₄Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, SiH₄Gas flow rate 43sccm, GeH₄Gas flow rate is 42 sccm, H₂The mass flow controllers 456, 457, and 458 adjusted the gas flow rate to 180 sccm. The opening of the conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 5 mTorr. Next, the RF power supply 424 is turned on at 0.60 W / cm.³And applied to the bias bar 428. Then, the power of the MW power supply (not shown) is increased to 0.25 W / cm.³MW power is introduced into the i-type layer deposition chamber 418 through the waveguide 426 and the microwave introduction window 425 to generate glow discharge, and the shutter 427 is opened to open the MWi type on the n / i buffer layer. When the production of the layer was started and the i-type layer having a thickness of 0.15 μm was produced, the MW glow discharge was stopped, the output of the bias power supply 424 was turned off, and the production of the MWi-type layer 204 was completed. The valves 451 and 452 are closed and the SiH into the i-type layer deposition chamber 418₄Gas, GeH₄Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0114]
Next, ap / i buffer layer 261 made of a-Si was formed by RFPCVD. In order to form the p / i buffer layer 261, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, and 453 are set. Open gradually, Si₂H₆Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 3 sccm, H₂The mass flow controllers 459 and 458 adjusted the gas flow rate to 75 sccm. The opening of a conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 0.7 Torr. Next, the RF power supply 424 is set to 0.07 W / cm³Is applied to the bias rod 428 to generate glow discharge, and by opening the shutter 427, the production of the p / i buffer layer 261 is started on the MWi-type layer. After the fabrication, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the fabrication of the p / i buffer layer 261 was completed. The valves 464 and 454 are closed to allow the Si to enter the i-type layer deposition chamber 418.₂H₆Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0115]
Next, in order to form the RF p-type layer 205 made of a-SiC, the gate valve 408 is opened into the transfer chamber 404 and the p-type layer deposition chamber 419 that have been evacuated in advance by a vacuum pump (not shown). 490 was conveyed. The back surface of the substrate 490 is brought into close contact with the substrate heating heater 412 and heated, and the pressure in the p-type layer deposition chamber 419 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0116]
The substrate heating heater 412 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate temperature becomes stable, H₂Gas, SiH₄/ H₂Gas, BF₃/ H₂(Dilution: 1%) Gas, CH₄The gas was introduced into the deposition chamber 419 through the gas introduction pipe 469 by operating the valves 481, 471, 470, 482, 472, 483, 473, 484, and 474. At this time, H₂Gas flow rate 60scm, SiH₄/ H₂Gas flow 0.4 sccm, BF₃/ H₂(Dilution: 1%) Gas flow rate is 1 sccm, CH₄The mass flow controllers 476, 477, 478, and 479 adjusted the gas flow rate to 0.3 sccm, and the opening of a conductance valve (not shown) was adjusted so that the pressure in the deposition chamber 419 became 1.7 Torr. The power of the RF power supply 423 is set to 0.07 W / cm³RF power is introduced into the plasma forming cup 421 to generate glow discharge, start forming an RFp-type layer on the p / i buffer layer, and form an RFp-type layer having a layer thickness of 10 nm. The power was turned off, the glow discharge was stopped, and the formation of the RFp type layer 205 was completed. Close the valves 472, 482, 473, 483, 474, 484 and place the SiH into the p-type layer deposition chamber 419.₄/ H₂Gas, BF₃/ H₂Gas, CH₄Stop the flow of gas and introduce H into the p-type layer deposition chamber 419 for 3 minutes.₂After the gas continues to flow, the valves 471, 481, and 470 are closed and H₂Is stopped, and the inside of the p-type layer deposition chamber 419 and the gas pipe is^-5Evacuated to Torr.
[0117]
Next, a hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed under the conditions shown in Table 2 (1). In order to carry out the hydrogen plasma treatment containing a trace amount of group III element of the present invention, BF is used as a group III element-containing gas.₃/ H₂(Dilution: 1%) gas, silicon atom-containing gas₂H₆Gas, H₂A gas is introduced into the deposition chamber 419 through a gas introduction pipe 469, and H₂The valves 481, 471, and 470 were opened so that the gas flow rate became 1000 sccm, and adjustment was performed by the mass flow controller 476. Group III element containing gas BF₃Gas is all H₂The valves 483 and 473 were opened so that the gas flow rate became 0.4%, and the mass flow controller 478 adjusted. The gas containing silicon atoms is Si₂H₆Is all H₂The valve (not shown) was opened to adjust the gas flow rate to 0.03% with a mass flow controller (not shown). The pressure in the deposition chamber 419 was adjusted with a conductance valve (not shown) so as to be 0.013 Torr. The substrate heating heater 412 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate temperature becomes stable, the VHF power of a VHF power supply (not shown) is reduced to 0.08 W / cm.³, VHF power was introduced into the plasma forming cup 421 to generate glow discharge, and the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed for 4 minutes. Thereafter, the VHF power supply is turned off, the glow discharge is stopped, and the BF₃/ H₂, Si₂H₆Stop the flow of gas and enter H into the deposition chamber 419 for 4 minutes.₂After continuing to flow gas, H₂The flow of gas was stopped, and the inside of the deposition chamber 419 and the inside of the gas pipe were^-5Evacuated to Torr.
[0118]
Next, in order to form the RF n-type layer 206 made of μc-Si, the gate valve 408 is introduced into the transfer chamber 402 and the deposition chamber 417 through the transfer chamber 403 previously evacuated by a vacuum pump (not shown). 407 was opened and transported. The back surface of the substrate 490 is brought into close contact with the substrate heating heater 410 and heated, and the pressure inside the deposition chamber 417 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0119]
To form an RF n-type layer made of μc-Si, H₂Gas deposition chamber
417 is introduced through a gas introduction pipe 429,₂The valves 441, 431, and 430 were opened so that the gas flow rate became 200 sccm, and adjustment was performed by the mass flow controller 436. The pressure in the deposition chamber 417 was adjusted to 1.1 Torr by a conductance valve (not shown). The substrate heating heater 410 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate temperature is stabilized, the SiH₄Gas, PH₃/ H₂The gas was introduced into the deposition chamber 417 through the gas introduction pipe 429 by operating the valves 443, 433, 444, and 434. At this time, SiH₄Gas flow rate 1.5 sccm, H₂Gas flow rate 80 sccm, PH₃/ H₂The mass flow controllers 438, 436, and 439 adjusted the gas flow rate to 250 sccm, and the pressure in the deposition chamber 417 was adjusted to 1.1 Torr. The power of the RF power supply 422 is set to 0.04 W / cm³RF power is introduced into the plasma forming cup 420 to cause glow discharge to start the formation of the RF n-type layer on the RF p-type layer. When the RF n-type layer having a thickness of 10 nm is formed, the RF power supply is turned on. Then, the glow discharge was stopped, and the formation of the RF n-type layer 206 was completed. SiH into the deposition chamber 417₄Gas, PH₃/ H₂The flow of H into the deposition chamber for 2 minutes.₂After continuing to flow gas, H₂Is stopped, and 1 × 10^{− 5}Evacuated to Torr.
[0120]
Next, an n / i buffer layer 252 made of a-SiC was formed by RFPCVD. First, the gate valve 407 was opened and the substrate 490 was transferred into the transfer chamber 403 and the i-type layer deposition chamber 418 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 411 and heated, and the pressure in the i-type layer deposition chamber 418 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0121]
To form the n / i buffer layer 252, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, 453, 465 and 455 are gradually opened, and Si₂H₆Gas, H₂Gas, CH₄The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 0.4 sccm, H₂Gas flow rate 90 sccm, CH₄The mass flow controllers 459, 458, and 460 adjusted the gas flow rate to 0.2 sccm.
[0122]
The opening of a conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 1.0 Torr. Next, the RF power supply 424 is set to 0.06 W / cm.³Is applied to the bias rod 428 to generate a glow discharge, and the shutter 427 is opened to start forming an n / i buffer layer on the RF n-type layer, thereby forming an n / i buffer layer having a layer thickness of 10 nm. Then, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the fabrication of the n / i buffer layer 252 was completed. The valves 464, 454, 465, 455 are closed and the Si into the i-type layer deposition chamber 418 is₂H₆Gas, CH₄Stop the flow of gas and place H in the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0123]
Next, an RFi-type layer 207 made of a-Si was formed by an RFPCVD method. To manufacture the RFi-type layer, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 200 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, and 453 are gradually opened. And Si₂H₆Gas, H₂The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 2 sccm, H₂The mass flow controllers 459 and 458 adjusted the gas flow rate to 85 sccm. The opening of a conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 0.5 Torr. Next, the RF power supply 424 is set to 0.07 W / cm³Is applied to the bias rod 428 to generate a glow discharge, and by opening the shutter 427, the production of the RFi-type layer is started on the n / i buffer layer 252 to produce an i-type layer having a layer thickness of 110 nm. The RF glow discharge was stopped, the output of the RF power source 424 was turned off, and the fabrication of the RFi-type layer 207 was completed. The valves 464 and 454 are closed to allow the Si to enter the i-type layer deposition chamber 418.₂H₆Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
Next, ap / i buffer layer 262 made of a-Sic was formed by RFPCVD. To form the p / i buffer layer 262, the substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 200 ° C., and when the substrate is sufficiently heated, the valves 464, 454, 450, 463, 453, 465 and 455 are gradually opened, and Si₂H₆Gas, H₂Gas, CH₄The gas was introduced into the i-type layer deposition chamber 418 through the gas introduction pipe 449. At this time, Si₂H₆Gas flow rate 0.4 sccm, H₂Gas flow rate 65 sccm, CH₄The mass flow controllers 459, 458, and 460 adjusted the gas flow rate to 0.3 sccm. The opening of the conductance valve (not shown) was adjusted so that the pressure in the i-type layer deposition chamber 418 became 1.1 Torr. Next, the RF power supply 424 is set to 0.06 W / cm.³Is applied to the bias rod 428 to generate a glow discharge, and the shutter 427 is opened to start forming a p / i buffer layer on the RFi-type layer, thereby forming a 15 nm thick p / i buffer layer. Then, the RF glow discharge was stopped, the output of the RF power supply 424 was turned off, and the production of the p / i buffer layer 262 was completed. The valves 464, 454, 465, 455 are closed and the Si into the i-type layer deposition chamber 418 is₂H₆Gas, CH₄Stop the flow of gas and introduce H into the i-type layer deposition chamber 418 for 2 minutes.₂After continuing the gas flow, the valves 453 and 450 are closed, and the inside of the i-type layer deposition chamber 418 and the gas pipe are^-5Evacuated to Torr.
[0124]
Next, in order to form the RF p-type layer 208 made of a-SiC, the gate valve 408 is opened into the transfer chamber 404 and the p-type layer deposition chamber 419 evacuated by a vacuum pump (not shown) in advance. 490 was conveyed. The back surface of the substrate 490 is brought into close contact with the substrate heating heater 412 and heated, and the pressure in the p-type layer deposition chamber 419 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0125]
The substrate heating heater 412 is set so that the temperature of the substrate 490 becomes 170 ° C.₂Gas, SiH₄/ H₂Gas, BF₃/ H₂(Dilution: 1%) Gas, CH₄The gas was introduced into the deposition chamber 419 through the gas introduction pipe 469 by operating the valves 481, 471, 470, 482, 472, 483, 473, 484, and 474. At this time, H₂Gas flow rate 70scm, SiH₄/ H₂Gas flow 0.4 sccm, BF₃/ H₂(Dilution: 1%) Gas flow rate is 1 sccm, CH₄The mass flow controllers 476, 477, 478, and 479 adjusted the gas flow rate to 0.3 sccm, and the opening of a conductance valve (not shown) was adjusted so that the pressure in the deposition chamber 419 became 1.7 Torr. The power of the RF power supply 423 is set to 0.07 W / cm³, And RF power is introduced into the plasma forming cup 421 to generate glow discharge, start forming an RFp-type layer on the p / i buffer layer 262, and form a 10-nm-thick RFp-type layer. The RF power was turned off to stop glow discharge, and the formation of the RF p-type layer 208 was completed. Close the valves 472, 482, 473, 483, 474, 484 and place the SiH into the p-type layer deposition chamber 419.₄/ H₂Gas, BF₃/ H₂Gas, CH₄Stop the flow of gas and introduce H into the p-type layer deposition chamber 419 for 2 minutes.₂After the gas continues to flow, the valves 471, 481, and 470 are closed and H₂Is stopped, and the inside of the p-type layer deposition chamber 419 and the gas^-5Evacuated to Torr.
[0126]
Next, the gate valve 409 was opened into the unload chamber 405 previously evacuated by the evacuation pump (not shown), the substrate 490 was transported, and the unload chamber 405 was leaked by opening the leak valve (not shown).
Next, as the transparent conductive layer 212, ITO having a layer thickness of 70 nm was vacuum-deposited on the RFp-type layer 208 by a vacuum deposition method.
[0127]
Next, a mask having a comb-shaped hole was placed on the transparent conductive layer 212, and a comb-shaped current collecting electrode 213 made of Cr (40 nm) / Ag (1000 nm) / Cr (40 nm) was vacuum-deposited by a vacuum deposition method.
Thus, the production of the solar cell has been completed. This solar cell will be referred to as (SC Ex. 2), and the hydrogen plasma treatment conditions of the present invention containing a small amount of Group III element, RF n-type layer, n / i buffer layer, MWi type layer, p / i buffer layer, RFi type Tables 2 (1) and 2 (2) show the conditions for forming the layers and the RFp-type layers.
[0128]
<Comparative Example 2>
A solar cell (SC ratio: 2) was produced under the same conditions as in Example 2 except that the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was not performed.
Nine solar cells (SC Ex. 2) and (SC ratio 2) were manufactured, each having an initial photoelectric conversion efficiency (photovoltaic power / incident optical power), vibration deterioration, light deterioration, and high temperature and high humidity when bias voltage was applied. Vibration degradation and light degradation in the environment were measured.
[0129]
The initial photoelectric conversion efficiency was measured using an AM1.5 (100 mW / cm²) It is obtained by installing under light irradiation and measuring VI characteristics. As a result of the measurement, the fill factor (FF), series resistance (Rs), and characteristic unevenness of the initial photoelectric conversion efficiency of (SC Ex. 2) with respect to (SC ratio 2) were as follows.

Vibration degradation was measured by placing a solar cell whose initial photoelectric conversion efficiency was measured in advance in a dark place with a humidity of 55% and a temperature of 28 ° C., and applying a vibration having a vibration frequency of 60 Hz and an amplitude of 0.1 mm for 550 hours. AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after vibration degradation test / initial photoelectric conversion efficiency) was used.
[0130]
The photodegradation was measured by installing a solar cell whose initial photoelectric conversion efficiency had been measured in advance in an environment of 55% humidity and a temperature of 28 ° C., and having an AM of 1.5 (100 mW / cm).²) After irradiation with light for 500 hours, AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after light degradation test / initial photoelectric conversion efficiency) was used. As a result of the measurement, the rate of decrease in photoelectric conversion efficiency after light degradation (SC ratio 2) and the rate of decrease in photoelectric conversion efficiency after vibration degradation with respect to (SC actual 2) were as follows.
[0131]

Vibration degradation and light degradation in a high temperature and high humidity environment at the time of bias application were measured. Two solar cells whose initial photoelectric conversion efficiency was measured in advance were placed in a dark place at a humidity of 90% and a temperature of 82 ° C., and 0.71 V was applied as a forward bias voltage. The above-mentioned vibration was applied to one of the solar cells to measure the vibration degradation, and the other solar cell was irradiated with AM1.5 light to measure the light degradation. As a result of the measurement, the reduction rate of the photoelectric conversion efficiency after the vibration deterioration of (SC ratio 2) and the reduction rate of the photoelectric conversion efficiency after the light deterioration of (SC ratio 2) with respect to (SC actual 2) are as follows.
[0132]

The state of delamination was observed using an optical microscope. In (SC Ex. 2), no delamination was observed, but in (SC ratio 2), delamination was slightly observed.
As described above, the solar cell (SC Ex. 2) of the present invention has a better fill factor, series resistance, characteristic unevenness, photodegradation property, adhesion, and so on in the photoelectric conversion efficiency of the solar cell than the conventional solar cell (SC Ex. 2). It was found that it had more excellent properties in durability.
[0133]
(Example 3)
The triple solar cell of FIG. 2 was manufactured using the deposition apparatus shown in FIG.
The base slope 490 provided with the reflection layer 301 and the reflection enhancement layer 302 prepared by the same method as in the first embodiment is disposed on the substrate transport rail 413 in the load chamber 401, and is operated by a vacuum pump (not shown). The pressure in the load chamber 401 is about 1 × 10^-5The system was evacuated to Torr.
[0134]
Next, the gate valve 406 was opened and transferred into the transfer chamber 402 and the deposition chamber 417 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 410 and heated, and the pressure inside the deposition chamber 417 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0135]
After the preparation for film formation was completed as described above, an RF n-type layer 303 made of μc-Si was formed in the same manner as in Example 1.
Next, the gate valve 407 was opened and transported into the transport chamber 403 and the deposition chamber 418 that were previously evacuated by a vacuum exhaust pump (not shown). The back surface of the substrate 490 is heated by bringing the back surface of the substrate 490 into close contact with the heater 411 for heating the substrate, and the pressure in the deposition chamber 418 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0136]
Next, an n / i buffer layer 351 made of a-Si, an MWi type layer 304 made of a-SiGe, a p / i buffer layer 361 made of a-Si, and a-SiC are formed in the same manner as in the first embodiment. The RFp type layer 305 was sequentially formed by the RFPCVD method and the MWPCVD method.
Next, the substrate 490 was transported into the deposition chamber 418 in the same manner as in Example 1 in order to carry out the hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention.
[0137]
Next, hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed under the conditions shown in Table 3 (1). In order to carry out the hydrogen plasma treatment containing a trace amount of a group III element according to the present invention, B gas as a group III element-containing gas is used.₂H₆/ H₂(Dilution: 10%) SiCl as gas and silicon atom-containing gas₂H₂/ He (dilution: 1000 ppm) gas, H₂A gas is introduced into the deposition chamber 418 through a gas introduction pipe 449, and H₂The valves 463, 453, and 450 were opened so that the gas flow rate became 1000 sccm, and adjustment was performed by the mass flow controller 458. Group III element-containing gas B₂H₆/ H₂(Dilution: 10%) Gas is all H₂The valves 468 and 466 were opened to adjust the gas flow rate to 2.2%, and the gas flow rate was adjusted by the mass flow controller 467. The silicon atom-containing gas is SiCl₂H₂/ He (dilution: 1000 ppm)₂SiCl to gas flow rate₂H₂The valve (not shown) was opened so that the gas ratio became 0.04%, and the gas flow was adjusted by a mass flow controller (not shown). The pressure in the deposition chamber 418 was adjusted with a conductance valve (not shown) so as to be 0.008 Torr. The substrate heating heater 411 is set so that the temperature of the substrate 490 becomes 300 ° C. When the substrate temperature is stabilized, the power of the MW power supply (not shown) is increased to 0.15 W / cm.³MW power is introduced into the i-type layer deposition chamber 418 through the waveguide 426 and the microwave introduction window 425 to generate a glow discharge, and the shutter 427 is opened. A group-element-containing hydrogen plasma treatment was performed. Thereafter, the MW power supply is turned off to stop the glow discharge, and the B gas is introduced into the deposition chamber 418.₂H₆/ H₂(Dilution 10%) Gas, SiCl₂H₂/ He (dilution: 1000 ppm) gas is stopped from flowing into the deposition chamber 418 for 4 minutes.₂After continuing to flow gas, H₂The flow of gas was also stopped, and the inside of the deposition chamber 418 and the inside of the gas pipe were^-5Evacuated to Torr.
[0138]
Next, the RF n-type layer 306 made of μc-Si, the n / i buffer layer 352 made of a-Si, the MWi type layer 307 made of a-SiGe, and the p / An i-buffer layer 362 and an RFp-type layer 308 made of a-SiC were sequentially formed by RFPCVD and MWPCVD.
Next, hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed under the conditions shown in Table 3 (2). In order to carry out the hydrogen plasma treatment containing a trace amount of a group III element according to the present invention, B gas as a group III element-containing gas is used.₂H₆/ H₂(Dilution: 10%) SiH as gas and silicon atom-containing gas₄Gas, H₂Gas is introduced into the deposition chamber 417 through the gas introduction pipe 429, and H₂The valves 441, 431, and 430 were opened so that the gas flow rate became 1300 sccm, and adjustment was performed by the mass flow controller 436. Group III element-containing gas B₂H₆Gas is all H₂The valve (not shown) was opened to adjust the gas flow rate to 1.3% with a mass flow controller (not shown). The gas containing silicon atoms is SiH₄Gas is all H₂The valves 443 and 433 were opened and adjusted by the mass flow controller 438 so that the gas flow rate became 0.04%. The pressure inside the deposition chamber 417 was adjusted with a conductance valve (not shown) so as to be 0.7 Torr. The substrate heating heater 410 is set so that the temperature of the substrate 490 becomes 250 ° C., and when the substrate temperature is stabilized, the power of the RF power supply 424 is reduced to 0.03 W / cm.³, RF power was introduced into the plasma forming cup 420 to generate glow discharge, and a hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed for 3 minutes. Thereafter, the RF power supply is turned off, the glow discharge is stopped, and B₂H₆/ H₂(Dilution: 10%) Gas, SiH₄Stop the flow of gas and enter H into the deposition chamber 417 for 3 minutes.₂After continuing to flow gas, H₂The flow of gas was also stopped, and the inside of the deposition chamber 417 and the gas pipe was^-5Evacuated to Torr.
[0139]
Next, the RF n-type layer 309 made of μc-Si, the n / i buffer layer 353 made of a-SiC, the RFi-type layer 310 made of a-Si, and the p / An i-buffer layer 363 and an RFp-type layer 311 made of a-SiC were sequentially formed by RFPCVD.
Next, as the transparent conductive layer 312, ITO having a thickness of 70 nm was vacuum-deposited on the RFp-type layer 311 by a vacuum deposition method.
[0140]
Next, a mask having a comb-shaped hole was placed on the transparent conductive layer 312, and a comb-shaped current collecting electrode 313 made of Cr (40 nm) / Ag (1000 nm) / Cr (40 nm) was vacuum-deposited by a vacuum deposition method.
Thus, the production of the solar cell has been completed. This solar cell is referred to as (SC Ex. 3), and the hydrogen plasma treatment conditions containing a trace amount of group III element of the present invention, RF n-type layer, n / i buffer layer, MWi type layer, p / i buffer layer, RFi type Tables 3 (1) to 3 (3) show the conditions for forming the layer and the RFp type layer.
[0141]
<Comparative Example 3>
A solar cell (SC ratio: 3) was manufactured under the same conditions as in Example 3 except that the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was not performed.
Seven solar cells (SC Ex. 3) and (SC ratio 3) were manufactured in each of 7 units, and the initial photoelectric conversion efficiency (photovoltaic power / incident optical power), vibration deterioration, light deterioration, and high temperature and high humidity environment when bias voltage was applied , Vibration degradation, light degradation, and reverse bias voltage application characteristics were measured.
[0142]
The initial photoelectric conversion efficiency was measured using an AM1.5 (100 mW / cm²) It is obtained by installing under light irradiation and measuring VI characteristics. As a result of the measurement, the fill factor (FF), series resistance (Rs), and characteristic unevenness of the initial photoelectric conversion efficiency of (SC Ex. 3) with respect to (SC ratio 3) were as follows.

The measurement of vibration deterioration is performed by placing a solar cell, whose initial photoelectric conversion efficiency has been measured in advance, in a dark place with a humidity of 55% and a temperature of 27 ° C., and applying a vibration having a vibration frequency of 60 Hz and an amplitude of 0.1 mm for 550 hours. AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after vibration degradation test / initial photoelectric conversion efficiency) was used.
[0143]
The photodegradation was measured by placing a solar cell, whose initial photoelectric conversion efficiency was measured in advance, in an environment with a humidity of 55% and a temperature of 27 ° C., and an AM of 1.5 (100 mW / cm).²) After irradiation with light for 550 hours, AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after light degradation test / initial photoelectric conversion efficiency) was used. As a result of the measurement, the rate of decrease in photoelectric conversion efficiency after light deterioration (SC ratio 3) and the rate of decrease in photoelectric conversion efficiency after vibration deterioration with respect to (SC actual 3) were as follows.
[0144]

Vibration degradation and light degradation in a high temperature and high humidity environment at the time of bias application were measured. Two solar cells whose initial photoelectric conversion efficiencies were measured in advance were placed in a dark place at a humidity of 90% and a temperature of 80 ° C., and 0.71 V was applied as a forward bias voltage. The above-mentioned vibration was applied to one of the solar cells to measure the vibration degradation, and the other solar cell was irradiated with AM1.5 light to measure the light degradation.
[0145]
As a result of the measurement, the reduction rate of the photoelectric conversion efficiency after the vibration deterioration of (SC ratio 3) and the reduction rate of the photoelectric conversion efficiency after the light deterioration of (SC ratio 3) are as follows with respect to (SC actual 3).

To measure the reverse bias voltage application characteristics, a solar cell whose initial photoelectric conversion efficiency has been measured in advance is placed in a dark place with a humidity of 53% and a temperature of 80 ° C., and a reverse bias voltage of 5.0 V is applied for 100 hours. After that, AM1.5 (100 mW / cm²) The photoelectric conversion efficiency under irradiation was measured, and the reduction rate (photoelectric conversion efficiency after application of reverse bias voltage / initial photoelectric conversion efficiency) was used.
[0146]
As a result of the measurement, the drop rate after application of the reverse bias voltage of (SC ratio 3) with respect to (SC actual 3) was as follows.
(SC ratio 3) 0.85 times
The state of delamination was observed using an optical microscope. In (SC Ex. 3), no delamination was observed, but in (SC ratio 3), delamination was slightly observed.
[0147]
As described above, the solar cell (SC Ex. 3) of the present invention has more fill factor, series resistance, characteristic unevenness, light deterioration characteristic, adhesion, and so on in the photoelectric conversion efficiency of the solar cell than the conventional solar cell (SC ratio 3). It has been found that the device has more excellent durability and reverse bias voltage application characteristics.
(Example 4)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 4 (1). A solar cell was fabricated. Table 4 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 4 (2) shows the manufacturing conditions of the triple solar cell.
[0148]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 4 (3).
The hydrogen flow rate of the hydrogen plasma treatment containing a trace amount of group III element of the present invention is 1 to 3 in the fill factor in the photoelectric conversion efficiency of the solar cell, the characteristic unevenness, the light deterioration characteristic, the series resistance characteristic, the durability, and the reverse bias voltage application characteristic. 2000 sccm was found to be a suitable flow rate.
[0149]
(Example 5)
The hydrogen plasma treatment containing a trace amount of group III element of the present invention was performed twice using the deposition apparatus shown in FIG. 3 under the conditions shown in Table 5 (1) as in Example 3. A solar cell was fabricated. Table 5 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 5 (2) shows the manufacturing conditions of the triple solar cell.
[0150]
In the same manner as in Example 3, the prepared triple solar cell was evaluated. The results are shown in Table 5 (3).
Even if the input power of the hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was changed from the RF power supply of Example 4 to the VHF power supply, the fill factor, the characteristic unevenness, the light deterioration characteristic, and the series resistance characteristic in the photoelectric conversion efficiency of the solar cell were obtained. It was found that the hydrogen flow rate was 1 to 2000 sccm in terms of durability, durability, and reverse bias voltage application characteristics.
[0151]
(Example 6)
The hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 6 (1) using the deposition apparatus shown in FIG. A solar cell was fabricated. Table 6 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 6 (2) shows the manufacturing conditions of the triple solar cell.
[0152]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 6 (3).
The amount of the Group III element-containing gas added to the hydrogen gas in the trace plasma of the Group III element-containing hydrogen plasma of the present invention is determined by the following factors: the fill factor in the photoelectric conversion efficiency of the solar cell, uneven characteristics, light degradation characteristics, and series resistance. In the characteristics, durability, and reverse bias voltage application characteristics, 0.05% to 3% were found to be preferable ranges.
[0153]
(Example 7)
The hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 7 (1) using the deposition apparatus shown in FIG. A solar cell was fabricated. Table 7 (1) shows the hydrogen plasma treatment conditions containing the collected group III element, and Table 7 (2) shows the fabrication conditions of the triple solar cell.
[0154]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 7 (3).
The addition amount of the Group III element-containing gas added to the hydrogen gas in the trace amount of Group III element-containing hydrogen plasma treatment of the present invention can be changed even if the input power is changed from the RF power supply of Embodiment 6 to the VHF power supply. It has been found that 0.05% to 3% is a preferable range in the fill factor in photoelectric conversion efficiency, characteristic unevenness, light deterioration characteristic, series low resistance characteristic, durability, and reverse bias voltage application characteristic.
[0155]
(Example 8)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 8 (1). A solar cell was fabricated. Table 8 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of group III element, and Table 8 (2) shows the manufacturing conditions of the triple solar cell.
[0156]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 8 (3).
The addition amount of the group III element-containing gas added to the hydrogen gas in the trace plasma of the group III element-containing hydrogen plasma of the present invention can be changed even if the input power is changed from the RF power supply of the sixth embodiment to the MW power supply. It has been found that 0.05% to 3% are preferable ranges in terms of the fill factor in photoelectric conversion efficiency, characteristic unevenness, light deterioration characteristic, series resistance characteristic, durability, and reverse bias voltage application characteristic.
[0157]
(Example 9)
The hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 9 (1) using the deposition apparatus shown in FIG. A solar cell was fabricated. Table 9 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 9 (2) shows the manufacturing conditions of the triple solar cell.
[0158]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 9 (3).
The amount of the silicon atom-containing gas added to the hydrogen gas in the trace plasma of the Group III element-containing hydrogen plasma of the present invention is determined by the fill factor in the photoelectric conversion efficiency of the solar cell, the characteristic unevenness, the light deterioration characteristic, the series resistance characteristic, It has been found that 0.001% to 0.1% is a preferable range in durability and reverse bias voltage application characteristics.
[0159]
(Example 10)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 10 (1). A solar cell was fabricated. Table 10 (1) shows the conditions for the treatment with the hydrogen plasma containing a trace amount of Group III element, and Table 10 (2) shows the conditions for manufacturing the triple solar cell.
[0160]
In the same manner as in Example 3, the fabricated triple solar cell was evaluated. The results are shown in Table 10 (3).
The addition amount of the silicon atom-containing gas to be added to the hydrogen gas in the hydrogen plasma treatment containing a trace amount of group III element according to the present invention can be changed even if the input power is changed from the RF power supply of the ninth embodiment to the VHF power supply. It was found that 0.001% to 0.1% is a preferable range in the fill factor in the efficiency, the characteristic unevenness, the light deterioration characteristic, the series resistance characteristic, the durability, and the reverse bias voltage application characteristic.
[0161]
(Example 11)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed twice under the conditions shown in Table 11 (1). A solar cell was fabricated. Table 11 (1) shows the conditions for the treatment with the hydrogen plasma containing a trace amount of Group III element, and Table 11 (2) shows the conditions for manufacturing the triple solar cell.
[0162]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 11 (3).
The addition amount of the silicon atom-containing gas to be added to the hydrogen gas in the hydrogen plasma treatment of the trace group III element-containing element of the present invention can be changed even if the input power is changed from the RF power supply of the ninth embodiment to the MW power supply. It was found that 0.001% to 0.1% is a preferable range in the fill factor in the efficiency, the characteristic unevenness, the light deterioration characteristic, the series resistance characteristic, the durability, and the reverse bias voltage application characteristic.
[0163]
(Example 12)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 12 (1). A solar cell was fabricated. Table 12 (1) shows the conditions of the treatment with the hydrogen plasma containing a trace amount of Group III element, and Table 12 (2) shows the manufacturing conditions of the triple solar cell.
[0164]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 12 (3).
The pressure of the trace Group III element-containing hydrogen plasma treatment of the present invention, when an RF power supply is used as input power, a fill factor in the photoelectric conversion efficiency of the solar cell, characteristic unevenness, light deterioration characteristic, series resistance characteristic, durability, It was found that 0.05 Torr to 10 Torr was a preferable range in the reverse bias voltage application characteristics.
[0165]
(Example 13)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 13 (1). A solar cell was fabricated. Table 13 (1) shows the conditions for the treatment with the hydrogen plasma containing a trace amount of Group III element, and Table 13 (2) shows the conditions for manufacturing the triple solar cell.
[0166]
In the same manner as in Example 3, the fabricated triple solar cell was evaluated. The results are shown in Table 13 (3).
When the VHF power supply is used as the input power, the pressure of the hydrogen plasma treatment containing a trace amount of group III element of the present invention is a fill factor in the photoelectric conversion efficiency of the solar cell, characteristic unevenness, light deterioration characteristic, series resistance characteristic, durability, It has been found that the preferable range of the reverse bias voltage application characteristic is 0.0001 Torr to 1 Torr.
[0167]
(Example 14)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed twice under the conditions shown in Table 14 (1). A solar cell was fabricated. Table 14 (1) shows the conditions for the treatment with the hydrogen plasma containing a trace amount of Group III element, and Table 14 (2) shows the conditions for manufacturing the triple solar cell.
[0168]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 14 (3).
When the MW power supply is used for the input power, the pressure of the trace amount of Group III element-containing hydrogen plasma treatment of the present invention is a fill factor in the photoelectric conversion efficiency of the solar cell, characteristic unevenness, light deterioration characteristic, series resistance characteristic, durability, It has been found that the preferable range is 0.0001 Torr to 0.01 Torr in the reverse bias voltage application characteristics.
[0169]
(Example 15)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 15 (1). A solar cell was fabricated. Table 15 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 15 (2) shows the manufacturing conditions of the triple solar cell.
[0170]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 15 (3).
The input power density (electric energy) of the hydrogen plasma treatment containing a trace amount of group III element according to the present invention is such that when an RF power source is used as the input power, the fill factor, the characteristic unevenness, the photodegradation characteristic, and the series in the photoelectric conversion efficiency of the solar cell. 0.01 W / cm in resistance characteristics, durability, and reverse bias voltage application characteristics³From 1.0W / cm³Was found to be a preferable range.
[0171]
(Example 16)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 16 (1). A solar cell was fabricated. Table 16 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of group III element, and Table 16 (2) shows the conditions for manufacturing the triple solar cell.
[0172]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 16 (3).
The input power density (electric energy) of the hydrogen plasma treatment containing a trace amount of group III element according to the present invention is as follows: when a VHF power supply is used as the input power, the fill factor, the characteristic unevenness, the light deterioration characteristic, 0.01 W / cm in resistance characteristics, durability, and reverse bias voltage application characteristics³From 1.0W / cm³Was found to be a preferable range.
[0173]
(Example 17)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 17 (1). A solar cell was fabricated. Table 17 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 17 (2) shows the conditions for manufacturing the triple solar cell.
[0174]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 17 (3).
The input power density (power amount) of the hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention is as follows: when an MW power source is used as the input power, the fill factor, the characteristic unevenness, the light deterioration characteristic, 0.1 W / cm in resistance characteristics and durability³From 10W / cm³Was found to be a preferable range.
[0175]
(Example 18)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 18 (1). A solar cell was fabricated. Table 18 (1) shows the conditions for the treatment with the hydrogen plasma containing a trace amount of Group III element, and Table 18 (2) shows the conditions for manufacturing the triple solar cell.
[0176]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 18 (3).
The substrate temperature of the hydrogen plasma treatment containing a trace amount of group III element according to the present invention is as follows. In the reverse bias voltage application characteristics, it was found that 100 ° C. to 400 ° C. was a preferable range.
[0177]
(Example 19)
As in Example 3, using the deposition apparatus shown in FIG. 3, the hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 19 (1). A solar cell was fabricated. Table 19 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 19 (2) shows the manufacturing conditions of the triple solar cell.
[0178]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 19 (3).
The substrate temperature in the hydrogen plasma treatment containing a trace amount of group III element according to the present invention is determined by using a VHF power supply as the input power, the fill factor in the photoelectric conversion efficiency of the solar cell, the characteristic unevenness, the light deterioration characteristic, the series resistance characteristic, and the durability. It was found that the preferable range was 50 ° C. to 300 ° C. in the reverse bias voltage application characteristics.
[0179]
(Example 20)
The hydrogen plasma treatment containing trace amounts of Group III elements of the present invention was performed twice under the conditions shown in Table 20 (1) using the deposition apparatus shown in FIG. A solar cell was fabricated. Table 20 (1) shows the conditions of the hydrogen plasma treatment containing a trace amount of Group III element, and Table 20 (2) shows the manufacturing conditions of the triple solar cell.
[0180]
In the same manner as in Example 3, the manufactured triple solar cell was evaluated. The results are shown in Table 20 (3).
When the MW power source is used as the input power, the substrate temperature of the hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention may be a fill factor in photoelectric conversion efficiency of a solar cell, characteristic unevenness, light deterioration characteristic, series resistance characteristic, It turned out that 50 degreeC-300 degreeC are the preferable ranges in durability.
[0181]
(Example 21)
The triple solar cell of FIG. 2 was manufactured using the deposition apparatus shown in FIG.
The substrate 490 provided with the reflection layer 301 and the reflection enhancement layer 302 prepared by the same method as in the first embodiment is arranged on the substrate transport rail 413 in the load chamber 401, and is loaded by a vacuum pump (not shown). The pressure inside the chamber 401 is about 1 × 10^-5The system was evacuated to Torr.
[0182]
Next, the gate valve 406 was opened and transferred into the transfer chamber 402 and the deposition chamber 417 that were previously evacuated by a vacuum pump (not shown). The back surface of the substrate 490 is brought into close contact with the substrate heating heater 410 and heated, and the pressure inside the deposition chamber 417 is reduced to about 1 × 10^-5The system was evacuated to Torr.
[0183]
Next, a hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (1). In order to perform hydrogen plasma treatment containing a trace amount of silane-based gas, SiH is used as a gas containing silicon atoms.₄/ H₂(Dilution: 1000 ppm) Gas, H₂Gas is introduced into the deposition chamber 417 through the gas introduction pipe 429, and H₂The valves 441, 431, and 430 were opened so that the gas flow rate became 1150 sccm, and adjustment was performed by the mass flow controller 436. The gas containing silicon atoms is H₂SiH to gas flow rate₄The valves 442 and 432 were opened so that the gas ratio was 0.03%, and the gas flow rate was adjusted by the mass flow controller 437. The pressure inside the deposition chamber 417 was adjusted with a conductance valve (not shown) so as to be 0.8 Torr. The substrate heating heater 410 is set so that the temperature of the substrate 490 becomes 360 ° C., and when the substrate temperature is stabilized, the power of the RF power supply 422 is reduced to 0.04 W / cm.³, And RF power was introduced, glow discharge was generated in the plasma forming cup 420, and hydrogen plasma treatment containing a trace amount of silane-based gas was performed for 3 minutes. Thereafter, the RF power is turned off to stop the glow discharge, and the SiH₄/ H₂(Dilution: 1000 ppm) Stop the inflow of gas and enter H into the deposition chamber 417 for 5 minutes.₂After continuing to flow gas, H₂The flow of gas was also stopped, and the inside of the deposition chamber 417 and the gas pipe was^-5Evacuated to Torr.
[0184]
After the preparation for film formation was completed as described above, an RF n-type layer 303 made of μc-Si was formed in the same manner as in Example 2.
Next, a hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (2). Next, an n / i buffer layer 351 made of a-SiC was formed by RFPCVD in the same manner as in Example 2.
[0185]
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (3). Next, an MWi type layer 304 made of a-SiGe was formed by the MWPCVD method in the same manner as in the second embodiment.
Next, a hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (4). Next, a p / i buffer layer 361 made of a-SiC was formed by RFPCVD in the same manner as in Example 2.
[0186]
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (5). Next, an RFp type layer 305 made of a-SiC was formed by an RFPCVD method in the same manner as in the second embodiment.
Next, a hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed under the conditions shown in Table 21 (6).
[0187]
Next, an RF n-type layer 306 made of μc-Si was formed by the RFPCVD method in the same manner as in Example 2.
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (7). Next, an n / i buffer layer 352 made of a-SiC was formed by RFPCVD in the same manner as in Example 2.
[0188]
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (8). Next, the MWi type layer 307 made of a-SiGe was formed by the MWPCVD method in the same manner as in the second embodiment.
Next, a hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (9). Next, a p / i buffer layer 362 made of a-SiC was formed by RFPCVD in the same manner as in Example 2.
[0189]
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (10). Next, an RFp-type layer 308 made of a-SiC was formed in the same manner as in Example 2.
Next, a hydrogen plasma treatment containing trace amounts of Group III elements according to the present invention was performed under the conditions shown in Table 21 (11).
[0190]
Next, an RF n-type layer 309 made of μc-Si was formed in the same manner as in Example 2.
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (12). Next, an n / i buffer layer 353 made of a-SiC was formed by RFPCVD in the same manner as in Example 2.
[0191]
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (13). Next, an RFi-type layer 310 made of a-Si was formed by an RFPCVD method in the same manner as in Example 2.
Next, hydrogen plasma treatment containing a small amount of silane-based gas was performed under the conditions shown in Table 21 (14). Next, a p / i buffer layer 363 made of a-SiC was formed by RFPCVD in the same manner as in Example 2.
[0192]
Next, hydrogen plasma treatment containing a trace amount of silane-based gas was performed under the conditions shown in Table 21 (15). Next, an RFp-type layer 311 made of a-SiC was formed by an RFPCVD method in the same manner as in Example 2.
Next, as the transparent conductive layer 312, ITO having a thickness of 70 nm was vacuum-deposited on the RFp-type layer 311 by a vacuum deposition method.
Next, a mask having a comb-shaped hole was placed on the transparent conductive layer 312, and a comb-shaped current collecting electrode 313 made of Cr (40 nm) / Ag (1000 nm) / Cr (40 nm) was vacuum-deposited by a vacuum deposition method.
[0193]
Thus, the production of the solar cell has been completed. This solar cell will be referred to as (SC Ex 21), and the conditions of the hydrogen plasma treatment containing trace group III elements and the hydrogen plasma containing trace silane-based gas of the present invention, RF n-type layer, n / i buffer layer, and MWi-type layer , P / i buffer layer, RFi-type layer, and RFp-type layer are shown in Tables 21 (1) to 21 (16).
[0194]
<Comparative Example 21>
A solar cell (SC ratio: 21) was manufactured under the same conditions as in Example 21 except that the hydrogen plasma treatment containing trace amounts of Group III elements and the hydrogen plasma treatment containing trace amounts of silane-based gas of the present invention were not performed.
Eight solar cells (SC actual 21) and (SC ratio 21) were manufactured respectively, and the initial photoelectric conversion efficiency (photovoltaic power / incident optical power), vibration deterioration, light deterioration, and high temperature and high humidity environment when bias voltage was applied , Vibration degradation, light degradation, and reverse bias voltage application characteristics were measured.
[0195]
The initial photoelectric conversion efficiency was measured using an AM1.5 (100 mW / cm²) It is obtained by installing under light irradiation and measuring VI characteristics. As a result of the measurement, with respect to (SC ratio 21), the fill factor (FF), series resistance (Rs), and characteristic unevenness of the initial photoelectric conversion efficiency of (SC actual 21) were as follows.

The measurement of the vibration deterioration is performed by placing a solar cell, whose initial photoelectric conversion efficiency has been measured in advance, in a dark place with a humidity of 57% and a temperature of 26 ° C., and applying a vibration having a vibration frequency of 60 Hz and an amplitude of 0.1 mm for 550 hours. AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after vibration degradation test / initial photoelectric conversion efficiency) was used. The photodegradation was measured by installing a solar cell whose initial photoelectric conversion efficiency had been measured in advance in an environment with a humidity of 57% and a temperature of 26 ° C., and an AM of 1.5 (100 mW / cm).²) After irradiation with light for 550 hours, AM1.5 (100 mW / cm²) The reduction rate of the photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after light degradation test / initial photoelectric conversion efficiency) was used.
[0196]
As a result of the measurement, the rate of decrease in photoelectric conversion efficiency after photodegradation (SC ratio 21) and the rate of decrease in photoelectric conversion efficiency after vibration degradation with respect to (SC actual 21) were as follows.

Vibration degradation and light degradation in a high temperature and high humidity environment at the time of bias application were measured. Two solar cells whose initial photoelectric conversion efficiencies were measured in advance were placed in a dark place at a humidity of 94% and a temperature of 83 ° C., and 0.71 V was applied as a forward bias voltage. The above-mentioned vibration was applied to one of the solar cells to measure the vibration deterioration, and the other solar cell was irradiated with AM1.5 light to measure the light deterioration.
[0197]
As a result of the measurement, the reduction rate of the photoelectric conversion efficiency after the vibration deterioration of (SC ratio 21) and the reduction rate of the photoelectric conversion efficiency after the light deterioration of (SC ratio 21) are as follows with respect to (SC actual 21).

To measure the reverse bias voltage application characteristics, a solar cell whose initial photoelectric conversion efficiency was measured in advance was placed in a dark place at a humidity of 52% and a temperature of 80 ° C., and a reverse bias voltage of 5.0 V was applied for 100 hours. After that, AM1.5 (100 mW / cm²) The photoelectric conversion efficiency under irradiation was measured, and the reduction rate (photoelectric conversion efficiency after application of reverse bias voltage / initial photoelectric conversion efficiency) was used.
[0198]
As a result of the measurement, the decrease rate after application of the reverse bias voltage of (SC ratio 21) with respect to (SC actual 21) was as follows.
(SC ratio 21) 0.83 times
The state of delamination was observed using an optical microscope. In (SC Ex. 21), no delamination was observed, but in (SC ratio 21), delamination was slightly observed. As described above, the solar cell (SC actual 21) of the present invention has a better fill factor, series resistance, characteristic unevenness, light degradation characteristic, adhesion, and so on than the conventional solar cell (SC ratio 21) in the photoelectric conversion efficiency of the solar cell. It has been found that the device has more excellent durability and reverse bias voltage application characteristics.
[0199]
In the above embodiment, the solar cell in which the n-type layer, the n / i buffer layer, the i-type layer, the p / i buffer layer, and the p-type layer are stacked in this order on the substrate has been described. With respect to a solar cell in which a p / i buffer layer, an i-type layer, an n / i buffer layer, and an n-type layer were stacked in this order, the same hydrogen plasma treatment was performed to produce a solar cell.
When the same evaluation as in the above example was performed, the solar cell in which the p-type layer and the n-type layer were plasma-treated with a hydrogen gas containing a silicon atom-containing gas and a gas containing a Group III element in the periodic table showed a photoelectric conversion. It has been confirmed that it has excellent characteristics such as a fill factor in efficiency, characteristic unevenness, light deterioration characteristic, series resistance characteristic, durability, and reverse bias voltage application characteristic. Further, the vicinity of the interface between the substrate and the p-type layer, the vicinity of the interface between the n / i buffer layer and the n-type layer, the vicinity of the interface between the n / i buffer layer and the i-type layer, the vicinity of the p / i buffer layer and the i-type layer. The above properties are further improved by performing a plasma treatment on the vicinity of the interface where the layers contact and the vicinity of the interface where the p / i buffer layer and the p-type layer come into contact with a hydrogen gas containing a silicon atom-containing gas to such an extent that substantially no deposition occurs. I understood that.
[0200]
[Table 1 (1)]

[0201]
[Table 1 (2)]

[0202]
[Table 2 (1)]

[0203]
[Table 2 (2)]

[0204]
[Table 3 (1)]

[0205]
[Table 3 (2)]

[0206]
[Table 3 (3)]

[0207]
[Table 4 (1)]

[0208]
[Table 4 (2)]

[0209]
[Table 4 (3)]

[0210]
[Table 5 (1)]

[0211]
[Table 5 (2)]

[0212]
[Table 5 (3)]

[0213]
[Table 6 (1)]

[0214]
[Table 6 (2)]

[0215]
[Table 6 (3)]

[0216]
[Table 7 (1)]

[0217]
[Table 7 (2)]

[0218]
[Table 7 (3)]

[0219]
[Table 8 (1)]

[0220]
[Table 8 (2)]

[0221]
[Table 8 (3)]

[0222]
[Table 9 (1)]

[0223]
[Table 9 (2)]

[0224]
[Table 9 (3)]

[0225]
[Table 10 (1)]

[0226]
[Table 10 (2)]

[0227]
[Table 10 (3)]

[0228]
[Table 11 (1)]

[0229]
[Table 11 (2)]

[0230]
[Table 11 (3)]

[0231]
[Table 12 (1)]

[0232]
[Table 12 (2)]

[0233]
[Table 12 (3)]

[0234]
[Table 13 (1)]

[0235]
[Table 13 (2)]

[0236]
[Table 13 (3)]

[0237]
[Table 14 (1)]

[0238]
[Table 14 (2)]

[0239]
[Table 14 (3)]

[0240]
[Table 15 (1)]

[0241]
[Table 15 (2)]

[0242]
[Table 15 (3)]

[0243]
[Table 16 (1)]

[0244]
[Table 16 (2)]

[0245]
[Table 16 (3)]

[0246]
[Table 17 (1)]

[0247]
[Table 17 (2)]

[0248]
[Table 17 (3)]

[0249]
[Table 18 (1)]

[0250]
[Table 18 (2)]

[0251]
[Table 18 (3)]

[0252]
[Table 19 (1)]

[0253]
[Table 19 (2)]

[0254]
[Table 19 (3)]

[0255]
[Table 20 (1)]

[0256]
[Table 20 (2)]

[0257]
[Table 20 (3)]

[0258]
[Table 21 (1)]

[0259]
[Table 21 (2)]

[0260]
[Table 21 (3)]

[0261]
[Table 21 (4)]

[0262]
[Table 21 (5)]

[0263]
[Table 21 (6)]

[0264]
[Table 21 (7)]

[0265]
[Table 21 (8)]

[0266]
[Table 21 (9)]

[0267]
[Table 21 (10)]

[0268]
[Table 21 (11)]

[0269]
[Table 21 (12)]

[0270]
[Table 21 (13)]

[0271]
[Table 21 (14)]

[0272]
[Table 21 (15)]

[0273]
[Table 21 (16)]

[0274]
【The invention's effect】
According to the present invention, impurities that become defect levels when taken into a semiconductor layer adsorbed on or contained in a deposition chamber wall usually seen in a hydrogen plasma treatment (eg, oxygen, nitrogen, carbon, iron, chromium, nickel, aluminum) Etc.) can be solved. In addition, stable hydrogen plasma processing can be performed. As a result,
1) It is possible to provide a photovoltaic element that is substantially free from peeling of the semiconductor layer when the photovoltaic element is placed at high temperature and high humidity.
[0275]
2) When a pin structure is formed on a flexible substrate, it is possible to provide a photovoltaic element in which a pin semiconductor layer is not easily peeled off even when the substrate is bent.
3) It is possible to provide a photovoltaic element in which an increase in defect levels near the interface between the substrate and the semiconductor layer is suppressed by long-time light irradiation.
4) Even when light is irradiated under high temperature and high humidity, it is possible to provide a photovoltaic element in which the substrate and the semiconductor layer do not peel off and the characteristic deterioration such as an increase in series resistance is suppressed.
[0276]
5) Even when used at a high temperature, it is possible to provide a photovoltaic element with less deterioration in characteristics.
6) It is possible to provide a photovoltaic element that is not easily broken when a reverse bias is applied to the photovoltaic element.
7) A photovoltaic element having a small series resistance can be provided even at the initial stage of forming the photovoltaic element.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of a photovoltaic element to which a method for forming a photovoltaic element according to the present invention is applied.
FIG. 2 is a schematic explanatory view of another photovoltaic element to which the method for forming a photovoltaic element of the present invention is applied.
FIG. 3 is a schematic explanatory view of a photovoltaic element forming apparatus suitable for the photovoltaic element forming method of the present invention.
[Explanation of symbols]
200,300 supports,
201, 301 reflective layer (or transparent conductive layer),
202, 302 reflection enhancement layer (or anti-reflection layer),
203, 303 first n-type layer (or p-type layer);
204, 304 a first i-type layer;
205, 305 first p-type layer (or n-type layer);
212, 312 transparent conductive layer (or conductive layer),
213,313 collecting electrode,
251,351 first n / i buffer layer,
261,361, the ith p / i buffer layer,
206, 306 a second n-type layer (or p-type layer);
207,307 second i-type layer;
208, 308 second p-type layer (or n-type layer);
252,352 second n / i buffer layer,
262,362 second p / i buffer layer;
309 third n (or p-type layer);
311 a third p-type layer (or n-type layer);
310 third i-type layer,
353 third n / i buffer layer;
363 third p / i buffer layer,
400 forming device,
401 load chamber,
402, 403, 404 transport chamber,
405 unload chamber,
406, 407, 408, 409 Gate valve,
410, 411, 412 substrate heater,
413 board transfer rail,
417 n-type (or p-type) layer deposition chamber;
418 i-type layer deposition chamber,
419 p-type (or n-type) layer deposition chamber;
420, 421 plasma forming cup,
422, 423, 424 power supply,
425 Microwave introduction window,
426 waveguide,
427 shutter,
428 bias rod,
429,449,469 gas introduction pipe,
430,431,432,433,434,441,442,443,444,450,451,452,453,454,455,461,462,463,464,465,468,466,470,471,472 473,474,481,482,483,484 valves,
436, 437, 438, 439, 456, 457, 458, 459, 460, 467, 476, 477, 478, 479 Mass flow controller,
490 Substrate holder.

Claims (5)

A non-single-crystal n-type layer (or p-type layer) containing silicon atoms, a non-single-crystal i-type n / i buffer layer (or p / i buffer layer), a non-single-crystal i-type layer, A photovoltaic element in which at least two or more pin structures each formed by laminating a single-crystal i-type p / i buffer layer (or n / i buffer layer) and a non-single-crystal p-type layer (or n-type layer) are laminated. In the vicinity of the interface where the p-type layer and the n-type layer are in contact with each other, a plasma treatment is performed using a hydrogen gas containing a silicon atom-containing gas and a group III element-containing gas that do not substantially deposit. A method for forming a photovoltaic element. The vicinity of the interface between the substrate and the n-type layer (or the vicinity of the interface between the substrate and the p-type layer) is plasma-treated with a hydrogen gas containing a silicon atom-containing gas to such an extent that substantially no deposition occurs. A method for forming a photovoltaic device according to claim 1. Near the interface where the n / i buffer layer and the n-type layer are in contact, near the interface where the n / i buffer layer and the i-type layer are in contact, near the interface where the p / i buffer layer and the i-type layer are in contact, and 3. The photovoltaic device according to claim 1, wherein the vicinity of the interface between the / i buffer layer and the p-type layer is plasma-treated with a hydrogen gas containing a gas containing a silicon atom to such an extent that substantially no deposition occurs. A method for forming a power element. The silicon atom-containing gas includes at least one of SiH ₄ , Si ₂ H ₆ , SiF ₄ , SiFH ₃ , SiF ₂ H ₂ , SiF ₃ H, SiCl ₂ H ₂ , SiCl ₃ H, and SiCl _4. The method for forming a photovoltaic element according to any one of claims 1 to 3, wherein 5. The method according to claim 1, wherein a content of the silicon atom-containing gas with respect to a hydrogen gas is 0.1% or less. 6.

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