JP2004274006A - Photovoltaic device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve output characteristics by reducing crystal defects in the vicinity of the surface of a crystal system semiconductor. <P>SOLUTION: This photovoltaic device comprises an n-type single crystal silicon substrate 1 and an amorphous silicon film 2 (substantially intrinsic undoped amorphous silicon film 2a and p-type amorphous silicon film 2b) that is formed on the top of the n-type single crystal silicon substrate 1. The concentration of the hydrogen atom (about 6×10<SP>21</SP>cm<SP>-3</SP>) of an interface between the n-type single crystal silicon substrate 1 and the undoped amorphous silicon film 2a is higher than the concentration of hydrogen atom in the undoped amorphous silicon film 2a. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

上記表１を参照して、６つの光起電力装置のｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面の水素原子面密度を、それぞれ、約５．３×１０^１３ｃｍ^−２、約１．２×１０^１４ｃｍ^−２、約２．５×１０^１４ｃｍ^−２、約１．９×１０^１５ｃｍ^−２（上記第１実施形態に対応するもの）、約２．１×１０^１６ｃｍ^−２および約１．３×１０^１７ｃｍ^−２とした。ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面の水素原子面密度は、上記した製造プロセスにおいて、ｎ型単結晶シリコン基板の上面を水素処理する際の水素ガスの流量を制御することにより制御される。なお、水素原子面密度が約５．３×１０^１３ｃｍ^−２の場合の光起電力装置では、水素処理は行われていない。この水素原子面密度が約５．３×１０^１３ｃｍ^−２の場合の水素原子は、ノンドープ非晶質シリコン膜の形成時に、原料ガスであるシラン（ＳｉＨ_４）中に含まれていた水素がｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面に導入されたものであると考えられる。
【００４２】
上記表１および図６を参照して、水素原子面密度が約１．２×１０^１４ｃｍ^−２〜約２．１×１０^１６ｃｍ^−２の場合の開放電圧Ｖ_ＯＣは、約０．６７１Ｖ〜約０．７０８Ｖとなり、水素処理を行わなかった水素原子面密度が約５．３×１０^１３ｃｍ^−２の場合の開放電圧Ｖ_ＯＣ（約０．６６５Ｖ）よりも向上することが判明した。また、水素原子面密度が約１．２×１０^１４ｃｍ^−２〜約２．１×１０^１６ｃｍ^−２の場合の曲線因子Ｆ．Ｆは、約０．７５７〜約０．７６５となり、水素処理を行わなかった水素原子面密度が約５．３×１０^１３ｃｍ^−２の場合の曲線因子Ｆ．Ｆ（約０．７３１）よりもより１に近づくことが判明した。また、水素原子面密度が約１．２×１０^１４ｃｍ^−２〜約２．１×１０^１６ｃｍ^−２の場合のセル出力Ｐ_ｍａｘは、約１．８７５Ｗ〜約２．０１６Ｗとなり、水素処理を行わなかった水素原子面密度が約５．３×１０^１３ｃｍ^−２の場合のセル出力Ｐ_ｍａｘ（約１．８１Ｗ）よりも向上することが判明した。これにより、水素処理を行った場合で、かつ、水素原子面密度が約１．２×１０^１４ｃｍ^−２〜約２．１×１０^１６ｃｍ^−２の範囲では、水素原子により結晶欠陥が不活性化されると考えられる。
【００４３】
その一方、水素処理を行った場合でも、水素原子面密度が約１．３×１０^１７ｃｍ^−２と高すぎる場合には、開放電圧Ｖ_ＯＣが約０．６４８Ｖ、および、セル出力Ｐ_ｍａｘが約１．７７７Ｗとなり、水素処理を行わなかった水素原子面密度が約５．３×１０^１３ｃｍ^−２の場合よりも、開放電圧Ｖ_ＯＣおよびセル出力Ｐ_ｍａｘが低下することが判明した。これは、水素処理時に、水素原子の量が多くなることに起因して水素のイオンエネルギが増加し、その結果、水素イオンがｎ型単結晶シリコン基板の表面に照射されて欠陥が発生したためであると考えられる。
【００４４】
上記表１および図６の結果より、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面の水素原子面密度が約１．２×１０^１４ｃｍ^−２以上約２．１×１０^１６ｃｍ^−２以下の場合に、開放電圧Ｖ_ＯＣ、曲線因子Ｆ．Ｆおよびセル出力Ｐ_ｍａｘを向上させることができる。したがって、上記した第１実施形態では、ｎ型単結晶シリコン基板１とノンドープ非晶質シリコン膜２ａとの界面の水素原子面密度を約１．９×１０^１５ｃｍ^−２に設定しているので、開放電圧Ｖ_ＯＣ、曲線因子Ｆ．Ｆおよびセル出力Ｐ_ｍａｘを向上させることができる。
【００４５】
（第２実施形態）
この第２実施形態では、上記第１実施形態と異なり、欠陥を不活性化するために、フッ素原子をｎ型単結晶シリコン基板中、ノンドープ非晶質シリコン膜中、および、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍に導入した場合の例について説明する。すなわち、この第２実施形態による光起電力装置では、製造プロセスの最初にｎ型単結晶シリコン基板を洗浄する工程中に、ｎ型単結晶シリコン基板をフッ酸で処理することによってフッ素原子を導入する。
【００４６】
具体的には、この第２実施形態では、ｎ型単結晶シリコン基板を洗浄する工程において、ｎ型単結晶シリコン基板の表面に対して、フッ酸（ＨＦ／Ｈ_２Ｏ）（約３ｍｏｌ／ｌ〜約１０ｍｏｌ／ｌのＨＦ含有量、室温）による処理を行った後、Ｈ_２Ｏリンス（室温、約１０秒〜約１０分）を行う。これにより、ｎ型単結晶シリコン基板の表面に、Ｈ_２Ｏリンスによって除去されなかったフッ酸の残留分が残る。なお、上記したフッ酸（ＨＦ／Ｈ_２Ｏ）の濃度およびＨ_２Ｏリンスのリンス時間を変化させることにより、導入されるフッ素原子の量を制御することができる。たとえば、フッ酸の濃度を大きくすれば、導入されるフッ素原子の量は多くなる。また、Ｈ_２Ｏリンスのリンス時間を短くすれば、フッ酸の残留分が多くなるので、導入されるフッ素原子の量は多くなる。
【００４７】
また、この第２実施形態では、上記第１実施形態のようなｎ型単結晶シリコン基板の表面の水素処理を行わない。なお、第２実施形態のこれら以外の部分の構造および製造プロセスは、上記第１実施形態と同様である。
【００４８】
第２実施形態では、上記のようなフッ酸処理およびＨ_２Ｏリンスによって、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面に、ｎ型単結晶シリコン基板の上面近傍の結晶欠陥を不活性化することが可能な量のフッ素原子（フッ素原子面密度：約１．５×１０^１２ｃｍ^−２）が導入される。また、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面に導入されたフッ素原子が、ｎ型単結晶シリコン基板中およびノンドープ非晶質シリコン膜中に拡散することにより、ｎ型単結晶シリコン基板中およびノンドープ非晶質シリコン膜中にフッ素原子が導入される。
【００４９】
図７には、第２実施形態による光起電力装置および比較例による光起電力装置のＳＩＭＳにより測定したｎ型単結晶シリコン基板の上面近傍のフッ素原子の濃度プロファイル図が示されている。このフッ素原子（Ｆ）の濃度プロファイルの測定には、Ｐｈｙｓｉｃａｌ ｅｌｅｃｔｒｏｎｉｃ Ｉｎｃｏｒｐｏｒａｔｉｏｎ製のＳＩＭＳ（ＡＤＥＰＴ １０１０）を用いた。このときの測定条件は、照射イオン種：Ｃｓ^＋イオン、イオン照射エネルギー：１ｋｅＶ、照射角度：６０°、検出二次イオン種：Ｆ⁻イオン、リファレンス二次イオン種：Ｓｉ⁻イオンであった。なお、ＳＩＭＳによる測定では、光起電力装置にＣｓ^＋イオンを照射して、たたき出された二次イオン（Ｆ⁻イオンおよびＳｉ⁻イオン）の数を測定するとともに、Ｓｉ⁻イオンの数［Ｓｉ⁻］に対するＦ⁻イオンの数［Ｆ⁻］の比（［Ｆ⁻］／［Ｓｉ⁻］、ただし、［Ｓｉ⁻］＝５．０×１０^２２／ｃｍ^３）を計算することにより、フッ素原子の濃度が求められる。
【００５０】
ここで、第２実施形態による光起電力装置では、上記した約３ｍｏｌ／ｌ〜約１０ｍｏｌ／ｌのＨＦ含有量で室温でのフッ酸処理および約１０秒〜約１０分間の室温でのＨ_２Ｏリンスを行った後、基板温度を約１７０℃に保持した状態で、シラン（ＳｉＨ_４）ガスを約４０ｓｃｃｍの流量で、かつ、約４０Ｐａの圧力で導入するとともに、約８．３３ｍＷ／ｃｍ^２の電力を供給することにより、ｎ型単結晶シリコン基板の上面上に、約５ｎｍ〜約２０ｎｍの厚みを有するノンドープ非晶質シリコン膜を形成した。つまり、この第２実施形態では、ノンドープ非晶質シリコン膜の形成前にフッ素の導入を行うとともに、ノンドープ非晶質シリコン膜の形成中はフッ素の導入を行っていない。その一方、比較例による光起電力装置では、上記した約３ｍｏｌ／ｌ〜約１０ｍｏｌ／ｌのＨＦ含有量で室温でのフッ酸処理および約１０秒〜約１０分間の室温でのＨ_２Ｏリンスを行った後、基板温度を約１７０℃に保持した状態で、フッ素（Ｆ）／シラン（ＳｉＨ_４）（ＳｉＨ_４ガスに対するＦの濃度：約０．２％で一定に保持）ガスを約４０ｓｃｃｍの流量で、かつ、約４０Ｐａの圧力で導入するとともに、約８．３３ｍＷ／ｃｍ^２の電力を供給することにより、ｎ型単結晶シリコン基板の上面上に、約５ｎｍ〜約２０ｎｍの厚みを有するノンドープ非晶質シリコン膜を形成した。すなわち、比較例では、ノンドープ非晶質シリコン膜の形成前のみならず、ノンドープ非晶質シリコン膜の形成中もフッ素を導入している。これ以外は、上記第２実施形態と同様にして比較例による光起電力装置を作製した。
【００５１】
図７を参照して、第２実施形態では、フッ素原子濃度のピークがｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍に位置しており、そのピーク濃度は、約１．０×１０^１９ｃｍ^−３であることがわかる。また、この第２実施形態では、上記第１実施形態と同様に、ＳＩＭＳ測定データの測定条件依存性を排除するために、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面のフッ素原子の量を、フッ素原子のピーク濃度を深さ方向に積分した面密度で規定する。すなわち、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面のフッ素原子面密度は、図７中の破線で示した曲線の積分値（図７中の斜線部の面積）であり、約１．５×１０^１２ｃｍ^−２である。
【００５２】
また、比較例では、ｎ型単結晶シリコン基板中からｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍にかけての領域では、第２実施形態と同様のフッ素原子の濃度プロファイルを示すことがわかる。その一方、比較例では、第２実施形態と異なり、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍に、フッ素原子の濃度ピークを有していない。具体的には、比較例による光起電力装置は、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面からノンドープ非晶質シリコン膜中にかけての領域では、ほぼ一定で、かつ、第２実施形態よりも大きなフッ素原子濃度（約１．０×１０^１９ｃｍ^−３）を有する。
【００５３】
第２実施形態において、図７に示すような濃度プロファイルが得られたのは、ｎ型単結晶シリコン基板表面のフッ酸処理によってｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍にフッ素原子の局所的に多い領域が形成されたためであると考えられる。これに対して、比較例において、図７に示すような濃度プロファイルが得られたのは、フッ酸処理に加えて、所定の割合でフッ素が混合されたフッ素／シランガスを用いてノンドープ非晶質シリコン膜を形成したことにより、ノンドープ非晶質シリコン膜の厚み方向に渡って、ほぼ均一な量で、かつ、第２実施形態よりも多くのフッ素原子が導入されたことによると考えられる。
【００５４】
第２実施形態では、上記のように、ｎ型単結晶シリコン基板およびノンドープ非晶質シリコン膜に、欠陥を不活性化することが可能なフッ素原子を導入することによって、導入されたフッ素原子がｎ型単結晶シリコン基板中およびノンドープ非晶質シリコン膜中の欠陥であるシリコン原子のダングリングボンドと結合することにより、ダングリングボンドを不活性化することができる。これにより、ｎ型単結晶シリコン基板中およびノンドープ非晶質シリコン膜中の欠陥を低減することができるので、欠陥にキャリアが捕獲されるのを抑制することができる。このため、ｎ型単結晶シリコン基板中およびノンドープ非晶質シリコン膜中でキャリアが再結合するのを抑制することができる。また、導入されたフッ素原子の濃度のピーク（ピーク濃度：約１．０×１０^１９ｃｍ^−３）がｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍に位置するとともに、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面のフッ素原子面密度を約１．５×１０^１２ｃｍ^−２にすることによって、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面のフッ素原子の量が増加するので、その増加したフッ素原子によりｎ型単結晶シリコン基板の上面近傍の結晶欠陥であるダングリングボンドを終端して不活性化することができる。これにより、ｎ型単結晶シリコン基板の上面近傍において、結晶欠陥を低減することができるので、結晶欠陥にキャリアが捕獲されるのを抑制することができる。このため、ｎ型単結晶シリコン基板の上面近傍でキャリアが再結合するのを抑制することができる。このように、ｎ型単結晶シリコン基板中、ノンドープ非晶質シリコン膜中およびｎ型単結晶シリコン基板の上面近傍でキャリアが再結合するのを抑制することができるので、光起電力装置の出力特性を向上させることができる。
【００５５】
また、第２実施形態では、比較例と異なり、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍にフッ素原子の濃度のピークが位置するように構成することによって、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面近傍のフッ素原子の量よりも、ノンドープ非晶質シリコン膜中のフッ素原子の量が多くなるのを抑制することができる。これにより、ノンドープ非晶質シリコン膜中に多くのフッ素原子が導入されることに起因してノンドープ非晶質シリコン膜の緻密さなどの膜特性が低下するのを抑制することができる。このため、ノンドープ非晶質シリコン膜の膜特性の低下に起因して光起電力装置の出力特性が低下するのを抑制することができる。
【００５６】
また、第２実施形態では、導入されたフッ素原子がシリコン原子のダングリングボンドと結合するので、シリコン原子の配位数が低減される。これにより、シリコン原子の柔軟性が増大するので、結晶欠陥であるシリコン原子のダングリングボンドが新たに発生するのを抑制することができる。
【００５７】
次に、上記した第２実施形態による効果を確認するために光起電力装置の出力特性を実際に測定した実験について説明する。具体的には、図７の第２実施形態のようなフッ素原子の濃度プロファイルを有する光起電力装置（実施例１）、および、図７の比較例のようなフッ素原子の濃度プロファイルを有する光起電力装置（比較例１）の出力特性（開放電圧Ｖ_ｏｃ、短絡電流Ｉ_ｓｃ、曲線因子Ｆ．Ｆおよびセル出力Ｐ_ｍａｘ）を測定した。そして、実施例１に対する比較例１の開放電圧Ｖ_ｏｃ、短絡電流Ｉ_ｓｃ、曲線因子Ｆ．Ｆおよびセル出力Ｐ_ｍａｘのそれぞれの比を計算した。その結果を以下の表２に示す。
【００５８】
【表２】

上記表２を参照して、実施例１に対する比較例１の出力特性の比（開放電圧Ｖ_ｏｃ：０．９９５、短絡電流Ｉ_ｓｃ：１．００１、曲線因子Ｆ．Ｆ：０．９９３およびセル出力Ｐ_ｍａｘ：０．９８９）は、短絡電流Ｉ_ｓｃを除いて、１より小さいことがわかる。これにより、実施例１では、比較例１と比べて、短絡電流Ｉ_ｓｃ以外の出力特性（開放電圧Ｖ_ｏｃ、曲線因子Ｆ．Ｆおよびセル出力Ｐ_ｍａｘ）が向上することがわかる。これは、比較例１では、実施例１と比べて、ノンドープ非晶質シリコン膜中により多くのフッ素原子が導入されているため、ノンドープ非晶質シリコン膜の緻密さなどの膜特性が低下したことにより出力特性が低下したことによると考えられる。
【００５９】
次に、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面のフッ素原子面密度の違いによる光起電力装置のセル出力Ｐ_ｍａｘを調べるために、フッ素原子面密度がそれぞれ異なる光起電力装置のセル出力Ｐ_ｍａｘを測定した。その測定結果について、図８を参照して説明する。なお、図８では、各光起電力装置のセル出力Ｐ_ｍａｘをフッ素原子面密度が１．０×１０^１２ｃｍ^−２のときのセル出力Ｐ_ｍａｘで規格化した値をセル出力の規格値として示している。
【００６０】
図８を参照して、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面でのフッ素原子面密度が１．０×１０^９ｃｍ^−２から大きくなるのに従って、セル出力が大きくなるとともに、フッ素原子面密度が１．０×１０^１２ｃｍ^−２付近でセル出力が最大となることがわかる。また、フッ素原子面密度が１．０×１０^１２ｃｍ^−２を超えると、セル出力が小さくなっていくことがわかる。フッ素原子面密度が１．０×１０^１２ｃｍ^−２付近までの範囲でセル出力が大きくなったのは、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面のフッ素原子の増加に伴ってｎ型単結晶シリコン基板の上面近傍の結晶欠陥であるシリコン原子のダングリングボンドがより不活性化されることに起因すると考えられる。また、フッ素原子面密度が１．０×１０^１２ｃｍ^−２付近を超えるとセル出力が小さくなっていくのは、ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面に導入されたフッ素原子の量が過剰となることに起因すると考えられる。具体的には、フッ素原子（Ｆ）の量が過剰になると結合エネルギー（結合力）の小さいＦ−Ｆ結合が発生するため、そのＦ−Ｆ結合が切れることに起因してｎ型単結晶シリコン基板の上面近傍の結晶欠陥であるダングリングボンドが増加するためであると考えられる。
【００６１】
また、図８を参照して、フッ素原子面密度が１．０×１０^１０ｃｍ^−２以上１．０×１０^１４ｃｍ^−２以下の範囲では、セル出力の規格値が０．８以上になることがわかる。フッ素原子面密度がこの範囲の光起電力装置では、良好な出力特性が得られることが本願発明者により確認されている。また、フッ素原子面密度が５．０×１０^１０ｃｍ^−２以上２．０×１０^１３ｃｍ^−２以下の範囲では、セル出力の規格値が０．９以上になることがわかる。フッ素原子面密度がこの範囲の光起電力装置では、より良好な出力特性が得られることが本願発明者により確認されている。
【００６２】
なお、今回開示された実施形態は、すべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は、上記した実施形態の説明ではなく特許請求の範囲によって示され、さらに特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれる。
【００６３】
たとえば、上記実施形態では、ｎ型単結晶シリコン基板１の上面上に、実質的に真性なノンドープ非晶質シリコン膜２ａを介してｐ型非晶質シリコン膜２ｂを形成するようにしたが、本発明はこれに限らず、ｐ型単結晶シリコン基板の上面上に、実質的に真性なノンドープ非晶質シリコン膜を介してｎ型非晶質シリコン膜を形成するようにしてもよい。
【００６４】
また、上記実施形態では、ｎ型単結晶シリコン基板１の裏面上に、非晶質シリコン膜１２（ノンドープ非晶質シリコン膜１２ａおよびｎ型非晶質シリコン膜１２ｂ）が形成されたＢＳＦ構造を有するようにしたが、本発明はこれに限らず、ｎ型単結晶シリコン基板の裏面上に、ｎ側の非晶質シリコン膜を形成せずに、裏面電極を形成するようにしてもよい。
【００６５】
また、上記実施形態では、ｐ側の膜形成を先に行うようにしたが、本発明はこれに限らず、ｎ側の膜形成を先に行うようにしてもよい。
【００６６】
また、上記実施形態では、ｎ型単結晶シリコン基板１とｐ型非晶質シリコン膜２ｂ（ｎ型非晶質シリコン膜１２ｂ）との間に、実質的に真性なノンドープ非晶質シリコン膜２ａ（ノンドープ非晶質シリコン膜１２ａ）を形成するようにしたが、本発明はこれに限らず、第１導電型の結晶系半導体と第２導電型の非晶質半導体膜との間に、実質的に真性なノンドープ非晶質シリコン膜を形成しなくてもよい。
【００６７】
また、上記実施形態では、ｎ型単結晶シリコン基板の上面近傍、ｎ型単結晶シリコン基板中およびノンドープ非晶質シリコン膜中の欠陥を不活性化するための不純物として、水素原子およびフッ素原子を導入した例について説明したが、本発明はこれに限らず、他の原子を導入してもよい。たとえば、塩素原子などを導入しても同様の効果を得ることができる。
【００６８】
また、上記実施形態では、本発明を光起電力装置のｐ側（表側）に適用した例について説明したが、本発明はこれに限らず、ｎ側（裏側）に適用した場合にも同様の効果を得ることができる。
【図面の簡単な説明】
【図１】本発明の第１実施形態による光起電力装置の構造を示した断面図である。
【図２】図１に示した第１実施形態による光起電力装置のｎ型単結晶シリコン基板１の上面近傍の水素原子の濃度プロファイル図である。
【図３】図１に示した第１実施形態による光起電力装置の製造プロセスを説明するための断面図である。
【図４】図１に示した第１実施形態による光起電力装置の製造プロセスを説明するための断面図である。
【図５】図１に示した第１実施形態による光起電力装置の製造プロセスを説明するための断面図である。
【図６】水素原子面密度とセル出力Ｐ_ｍａｘとの関係を示したグラフである。
【図７】本発明の第２実施形態による光起電力装置および比較例による光起電力装置のＳＩＭＳにより測定したｎ型単結晶シリコン基板の上面近傍のフッ素原子の濃度プロファイル図である。
【図８】ｎ型単結晶シリコン基板とノンドープ非晶質シリコン膜との界面のフッ素原子面密度とセル出力との関係を示した図である。
【符号の説明】
１ ｎ型単結晶シリコン基板（結晶系半導体）
２、１２ 非晶質シリコン膜
２ａ、１２ａ ノンドープ非晶質シリコン膜（非晶質半導体膜、第１非晶質半導体膜）
２ｂ ｐ型非晶質シリコン膜（非晶質半導体膜、第２非晶質半導体膜）
１２ｂ ｎ型非晶質シリコン膜（非晶質半導体膜、第２非晶質半導体膜）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photovoltaic device and a method of manufacturing the same, and more particularly, to a photovoltaic device in which an amorphous semiconductor film is formed on a crystalline semiconductor and a method of manufacturing the same.
[0002]
[Prior art]
Conventionally, in a photovoltaic device in which a pn junction is formed by forming a second conductivity type amorphous silicon film on a surface of a first conductivity type crystal silicon substrate, a first conductivity type crystal silicon substrate is used. There is known a technique for improving junction characteristics by inserting a substantially intrinsic amorphous silicon film between a silicon substrate and a second conductivity type amorphous silicon film (for example, Patent Document 1). reference). Patent Document 1 discloses that a substantially intrinsic amorphous silicon film and a p-type amorphous silicon film are sequentially formed on an n-type single crystal silicon substrate, and the n-type single crystal silicon substrate is formed. There is disclosed a photovoltaic device in which boron is introduced between an amorphous silicon film and a substantially intrinsic amorphous silicon film. In Patent Document 1, a substantially intrinsic non-doped amorphous silicon film is formed on an n-type single crystal silicon substrate at a low temperature of about 200 ° C. or less using a plasma CVD method. Unlike the case where a pn junction is formed by diffusing p-type impurities from the surface of an n-type single crystal silicon substrate by using a thermal diffusion method at a high temperature of not less than ℃, thermal damage can be suppressed, and Mutual diffusion between the n-type impurity and the n-type impurity can be suppressed. As a result, good bonding characteristics can be obtained.
[0003]
[Patent Document 1]
JP 2001-345463 A
[Problems to be solved by the invention]
However, in the photovoltaic device disclosed in Patent Literature 1, sufficient measures have not been taken to reduce (inactivate) dangling bonds, which are crystal defects near the surface of the single crystal silicon substrate. . For this reason, there is an inconvenience that carriers are captured by dangling bonds which are crystal defects near the surface of the single crystal silicon substrate. In this case, there is a problem that the output characteristics of the photovoltaic device deteriorate because carriers recombine near the surface of the single-crystal silicon substrate and disappear. For this reason, it has been difficult to improve the output characteristics of the photovoltaic device.
[0004]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and one object of the present invention is to improve output characteristics by reducing crystal defects near the surface of a crystalline semiconductor. To provide a possible photovoltaic device.
[0005]
Another object of the present invention is to provide a photovoltaic device capable of improving output characteristics by reducing defects in a crystalline semiconductor and an amorphous semiconductor film.
[0006]
Still another object of the present invention is to provide a method of manufacturing a photovoltaic device capable of improving output characteristics by reducing crystal defects near the surface of a crystalline semiconductor.
[0007]
Means for Solving the Problems and Effects of the Invention
To achieve the above object, a photovoltaic device according to a first aspect of the present invention includes a crystalline semiconductor, and an amorphous semiconductor film formed on a surface of the crystalline semiconductor. The hydrogen atom concentration at the interface with the amorphous semiconductor film is higher than the hydrogen atom concentration in the amorphous semiconductor film. Note that the crystalline semiconductor in the present invention is a broad concept including a crystalline semiconductor substrate and a thin-film polycrystalline semiconductor formed on the substrate. Further, the amorphous semiconductor in the present invention is a broad concept including a microcrystalline semiconductor.
[0008]
In the photovoltaic device according to the first aspect, as described above, the hydrogen atom concentration at the interface between the crystalline semiconductor and the amorphous semiconductor film is set higher than the hydrogen atom concentration in the amorphous semiconductor film. As a result, the amount of hydrogen atoms at the interface between the crystalline semiconductor and the amorphous semiconductor film increases, and the increased hydrogen atoms terminate dangling bonds of silicon atoms, which are crystal defects near the surface of the crystalline semiconductor. Can be inactivated. Thus, crystal defects in the vicinity of the surface of the crystalline semiconductor can be reduced, so that capture of carriers by the crystal defects can be suppressed. As a result, recombination of carriers near the surface of the crystalline semiconductor can be suppressed, so that the output characteristics of the photovoltaic device can be improved. Further, dangling bonds of silicon atoms are terminated by hydrogen atoms, so that the coordination number of silicon atoms is reduced. As a result, the flexibility of silicon atoms is increased, so that the generation of new dangling bonds of silicon atoms, which are crystal defects, can be suppressed.
[0009]
In the photovoltaic device according to the first aspect, preferably, the interface between the crystalline semiconductor and the amorphous semiconductor film has an amount capable of inactivating crystal defects near the surface of the crystalline semiconductor. A hydrogen atom has been introduced. According to this structure, the dangling bond which is a crystal defect near the surface of the crystalline semiconductor can be easily inactivated, so that the dangling bond which is a crystal defect near the surface of the crystalline semiconductor can be easily formed. Can be reduced.
[0010]
In the photovoltaic device according to the first aspect, preferably, the hydrogen atom surface density at the interface between the crystalline semiconductor and the amorphous semiconductor film is 1.2 × 10 ¹⁴ cm ^-2 2.1 × 10 ¹⁶ cm ^-2 It is as follows. With such a structure, the amount of hydrogen atoms at the interface between the crystalline semiconductor and the amorphous semiconductor film can be easily changed to inactivate dangling bonds, which are crystal defects near the surface of the crystalline semiconductor. Can be as much as possible.
[0011]
In the photovoltaic device according to the first aspect, preferably, the concentration of hydrogen atoms at the interface between the crystalline semiconductor and the amorphous semiconductor film is higher than the concentration of hydrogen atoms in the crystalline semiconductor, and The hydrogen atom concentration in the inside is lower than the hydrogen atom concentration in the amorphous semiconductor film. With such a structure, the amount of hydrogen atoms at the interface between the crystalline semiconductor and the amorphous semiconductor film increases, so that the increased hydrogen atoms reduce crystal defects near the surface of the crystalline semiconductor having a low hydrogen concentration. Can be inactivated.
[0012]
In the photovoltaic device according to the first aspect, preferably, the amorphous semiconductor film includes a substantially intrinsic first amorphous semiconductor film formed on the surface of the crystalline semiconductor and a first amorphous semiconductor film. And a second amorphous semiconductor film of the first conductivity type formed on the surface of the amorphous semiconductor film. According to this structure, the lattice mismatch between the crystalline semiconductor and the second amorphous semiconductor film can be reduced by the substantially intrinsic first amorphous semiconductor film, so that the junction characteristics are improved. be able to.
[0013]
A photovoltaic device according to a second aspect of the present invention includes a crystalline semiconductor and an amorphous semiconductor film formed on a surface of the crystalline semiconductor, wherein the crystalline semiconductor and the amorphous semiconductor film include: An impurity capable of inactivating a defect is introduced, and a peak of the impurity concentration is located near an interface between the crystalline semiconductor and the amorphous semiconductor film.
[0014]
In the photovoltaic device according to the second aspect, as described above, by introducing an impurity capable of inactivating a defect into the crystalline semiconductor and the amorphous semiconductor film, the introduced impurity is reduced. The dangling bond can be inactivated by bonding with a dangling bond of a silicon atom which is a defect in the crystalline semiconductor and the amorphous semiconductor film. Thus, defects in the crystalline semiconductor and the amorphous semiconductor film can be reduced, so that carriers can be suppressed from being captured by the defects. Therefore, recombination of carriers in the crystalline semiconductor and the amorphous semiconductor film can be suppressed. In addition, since the peak of the concentration of the introduced impurity is located near the interface between the crystalline semiconductor and the amorphous semiconductor film, the amount of impurities at the interface between the crystalline semiconductor and the amorphous semiconductor film increases. The dangling bond, which is a crystal defect near the surface of the crystalline semiconductor, can be terminated and inactivated by the increased impurities. Accordingly, crystal defects can be reduced in the vicinity of the surface of the crystalline semiconductor, so that capture of carriers by the crystal defects can be suppressed. Therefore, recombination of carriers near the surface of the crystalline semiconductor can be suppressed. As described above, recombination of carriers in the crystalline semiconductor, the amorphous semiconductor film, and the vicinity of the surface of the crystalline semiconductor can be suppressed, so that the output characteristics of the photovoltaic device can be improved. . In addition, since the impurity concentration peak is located near the interface between the crystalline semiconductor and the amorphous semiconductor film, the impurity concentration is higher than the amount of impurities near the interface between the crystalline semiconductor and the amorphous semiconductor film. An increase in the amount of impurities in the semiconductor film can be suppressed. Thus, it is possible to suppress a decrease in film characteristics such as the denseness of the amorphous semiconductor film due to the introduction of many impurities into the amorphous semiconductor film. Therefore, it is possible to suppress a decrease in output characteristics of the photovoltaic device due to a decrease in film characteristics of the amorphous semiconductor film. Further, since the introduced impurities bond with dangling bonds of silicon atoms, the coordination number of silicon atoms is reduced. As a result, the flexibility of silicon atoms is increased, so that the generation of new dangling bonds of silicon atoms, which are crystal defects, can be suppressed.
[0015]
In the photovoltaic device according to the second aspect, preferably, the impurity is one of a hydrogen atom and a fluorine atom. When such an atom is used, a dangling bond of a silicon atom which is a defect in a crystalline semiconductor, an amorphous semiconductor film, and a vicinity of a surface of the crystalline semiconductor can be easily inactivated. Thereby, the output characteristics of the photovoltaic device can be easily improved. This point has been confirmed by experiments performed by the present inventor.
[0016]
In this case, preferably, an amount of fluorine atoms capable of inactivating crystal defects near the surface of the crystalline semiconductor is introduced into the interface between the crystalline semiconductor and the amorphous semiconductor film. According to this structure, the dangling bond which is a crystal defect near the surface of the crystalline semiconductor can be easily inactivated, so that the dangling bond which is a crystal defect near the surface of the crystalline semiconductor can be easily formed. Can be reduced.
[0017]
In this case, preferably, the fluorine atom surface density at the interface between the crystalline semiconductor and the amorphous semiconductor film is 1 × 10 ¹⁰ cm ^-2 More than 1 × 10 ¹⁴ cm ^-2 It is as follows. According to this structure, the amount of fluorine atoms at the interface between the crystalline semiconductor and the amorphous semiconductor film can be easily changed to inactivate dangling bonds that are crystal defects near the surface of the crystalline semiconductor. Can be as much as possible.
[0018]
In this case, preferably, the fluorine atom surface density at the interface between the crystalline semiconductor and the amorphous semiconductor film is 5 × 10 ¹⁰ cm ^-2 More than 2 × 10 ^Thirteen cm ^-2 It is as follows. According to this structure, dangling bonds, which are crystal defects near the surface of the crystalline semiconductor, can be more inactivated.
[0019]
A method of manufacturing a photovoltaic device according to a third aspect of the present invention includes a step of subjecting a surface of a crystalline semiconductor to hydrogen treatment with a predetermined flow rate of hydrogen gas, and thereafter, without performing gas replacement by high vacuum exhaustion. Forming an amorphous semiconductor film on the surface of the crystalline semiconductor. Here, the replacement of gas by high-vacuum exhaust means that gas replacement is performed at a degree of vacuum of about 1 Pa or less, for example.
[0020]
In the method for manufacturing a photovoltaic device according to the third aspect, as described above, after the surface of the crystalline semiconductor is hydrogen-treated with a predetermined flow rate of hydrogen gas, the gas is not replaced by high vacuum evacuation, By forming an amorphous semiconductor film on the surface of the crystalline semiconductor, it is possible to prevent hydrogen atoms adsorbed in an unstable state near the surface of the crystalline semiconductor from being removed by high vacuum evacuation. it can. In this case, the state in which the amount of hydrogen atoms at the interface between the crystalline semiconductor and the amorphous semiconductor film is increased is maintained, and the increased hydrogen atoms cause the removal of silicon atoms which are crystal defects near the surface of the crystalline semiconductor. The dangling bond can be terminated and inactivated. Thus, crystal defects in the vicinity of the surface of the crystalline semiconductor can be reduced, so that capture of carriers by the crystal defects can be suppressed. As a result, recombination of carriers near the surface of the crystalline semiconductor can be suppressed, so that the output characteristics of the photovoltaic device can be improved. Further, dangling bonds of silicon atoms are terminated by hydrogen atoms, so that the coordination number of silicon atoms is reduced. As a result, the flexibility of silicon atoms is increased, so that the generation of new dangling bonds of silicon atoms, which are crystal defects, can be suppressed.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
(1st Embodiment)
FIG. 1 is a sectional view showing the structure of the photovoltaic device according to the first embodiment of the present invention. First, the structure of the photovoltaic device according to the first embodiment will be described with reference to FIG.
[0023]
In the photovoltaic device according to the first embodiment, as shown in FIG. 1, an amorphous silicon film 2 having a thickness of about 70 nm to about 100 nm is formed on an upper surface of a hydrogen-treated n-type single crystal silicon substrate 1. A surface electrode 3 made of ITO (indium tin oxide) and a collector electrode 4 made of silver having a thickness of several tens of μm are sequentially formed. The amorphous silicon film 2 includes a substantially intrinsic non-doped amorphous silicon film 2 a having a thickness of about 5 nm to about 20 nm formed on the upper surface of the n-type single crystal silicon substrate 1, and a non-doped amorphous silicon film. And a p-type amorphous silicon film 2b doped with boron (B) and having a thickness of about 3 nm to about 10 nm formed on the film 2a. The n-type single-crystal silicon substrate 1 is an example of the “crystalline semiconductor” of the present invention. The non-doped amorphous silicon film 2a is an example of the “amorphous semiconductor film” and “first amorphous semiconductor film” of the present invention, and the p-type amorphous silicon film 2b is It is an example of an “amorphous semiconductor film” and a “second amorphous semiconductor film”.
[0024]
On the back surface of the hydrogen-treated n-type single-crystal silicon substrate 1, the amorphous silicon film 12 has a thickness of about 70 nm to about 100 nm in order from the side closer to the back surface of the n-type single-crystal silicon substrate 1. A back electrode 13 made of ITO and a collector electrode 14 made of silver having a thickness of several tens of μm are formed. The amorphous silicon film 12 includes a substantially intrinsic non-doped amorphous silicon film 12a having a thickness of about 5 nm to about 40 nm formed on the back surface of the n-type single crystal silicon substrate 1, and a non-doped amorphous silicon film. And a phosphorus (P) -doped n-type amorphous silicon film 12b having a thickness of about 5 nm to about 40 nm formed on the back surface of the film 12a. The non-doped amorphous silicon film 12a, the n-type amorphous silicon film 12b, and the back electrode 13 form a so-called BSF (Back Surface Field) structure. The non-doped amorphous silicon film 12a is an example of the “amorphous semiconductor film” and “first amorphous semiconductor film” of the present invention, and the n-type amorphous silicon film 12b is It is an example of an “amorphous semiconductor film” and a “second amorphous semiconductor film”.
[0025]
Here, in the first embodiment, it is possible to inactivate crystal defects near the upper surface of the n-type single-crystal silicon substrate 1 at the interface between the n-type single-crystal silicon substrate 1 and the non-doped amorphous silicon film 2a. An appropriate amount of hydrogen atoms has been introduced. Hereinafter, this point will be described in detail.
[0026]
FIG. 2 is a concentration profile diagram of hydrogen atoms near the upper surface of the n-type single crystal silicon substrate 1 of the photovoltaic device according to the first embodiment shown in FIG. Note that the solid line in FIG. 2 is a hydrogen atom concentration profile measured by SIMS (Secondary Ion Mass Spectrometer). The dashed line in FIG. 2 is a curve obtained by fitting the hydrogen atom concentration at the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a with a normal function (Gaussian function). For the measurement of the concentration profile of the hydrogen atoms (H), SIMS (ADEPT 1010) manufactured by Physical electronic Incorporation was used. The measurement conditions at this time are irradiation ion species: Cs ⁺ Ion, ion irradiation energy: 1 keV, irradiation angle: 60 °, secondary ion species detected: H ⁻ Ion, reference secondary ion species: Si ⁻ It was an ion. In the measurement by SIMS, the photovoltaic device has Cs ⁺ The secondary ions (H ⁻ Ions and Si ⁻ Ion) and the number of Si ⁻ Number of ions [Si ⁻ H to ⁻ Number of ions [H ⁻ ] ([H ⁻ ] / [Si ⁻ ] Except that [Si ⁻ ] = 5.0 × 10 ²² / Cm ³ ), The concentration of hydrogen atoms is determined.
[0027]
With reference to the solid line (SIMS measurement data) in FIG. 2, in the first embodiment, the hydrogen atom concentration at the interface between the n-type single-crystal silicon substrate 1 and the non-doped amorphous silicon film 2a is n-type single-crystal silicon. It can be seen that the concentration of hydrogen atoms in the substrate 1 and the concentration of hydrogen atoms in the non-doped amorphous silicon film 2a are higher. That is, the peak concentration of hydrogen atoms is located at the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a, and the peak concentration is about 6.0 × 10 ²¹ cm ^-3 It is.
[0028]
Here, when the impurity concentration in an extremely thin region such as the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a is measured by SIMS, the measured value depends on the measurement conditions and the measurement device. It has been known. For example, under a measurement condition in which the resolution in the depth direction is low, the value of the peak concentration is low and the half width is wide. On the other hand, under a measurement condition with a high resolution in the depth direction, the value of the peak concentration increases and the half width decreases. Further, when the resolution of the measuring device is low, the value of the peak concentration is low and the half width is wide. On the other hand, when the resolution of the measuring device is high, the value of the peak concentration increases and the half width decreases. For this reason, in the first embodiment, the peak concentration of hydrogen atoms at the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a is set to It is defined by the surface density integrated in the vertical direction. That is, the hydrogen atom surface density at the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a is represented by the integral value of the curve shown by the broken line in FIG. 2 (the area of the hatched portion in FIG. 2). Yes, about 1.9 × 10 ^Fifteen cm ^-2 It becomes.
[0029]
3 to 5 are cross-sectional views for explaining the manufacturing process of the photovoltaic device according to the first embodiment shown in FIG. Next, the manufacturing process of the photovoltaic device according to the first embodiment will be described with reference to FIG. 1 and FIGS.
[0030]
First, as shown in FIG. 3, after cleaning the n-type single-crystal silicon substrate 1 in a vacuum chamber (not shown), the n-type single-crystal silicon substrate 1 is removed under a temperature condition of about 200 ° C. or less. By heating, moisture adhering to the surface of the n-type single crystal silicon substrate 1 is removed as much as possible. Thereby, it is suppressed that oxygen in moisture adhering to the surface of the n-type single crystal silicon substrate 1 is combined with silicon to become a crystal defect.
[0031]
Next, with the substrate temperature kept at about 170 ° C., hydrogen (H ₂ ) While introducing gas, about 3 mW / cm ² ~ 30mW / cm ² Is supplied, the upper surface of the n-type single crystal silicon substrate 1 is subjected to hydrogen treatment. At this time, in the first embodiment, the upper surface of the n-type single crystal silicon substrate 1 is cleaned by introducing hydrogen gas at a flow rate of about 500 sccm to about 2000 sccm and at a pressure of about 50 Pa to about 200 Pa. In the vicinity of the upper surface of n-type single-crystal silicon substrate 1, an amount of hydrogen atoms capable of inactivating crystal defects on the upper surface of n-type single-crystal silicon substrate 1 is adsorbed.
[0032]
Thereafter, in the first embodiment, the gas is not replaced by high vacuum evacuation (evacuation at a degree of vacuum of about 1 Pa or less), and an n-type single crystal is formed by using a plasma CVD method as shown in FIG. On the upper surface of the silicon substrate 1, a non-doped amorphous silicon film 2a is formed. Specifically, with the substrate temperature kept at about 170 ° C., silane (SiH ₄ ) Gas is introduced at a flow rate of about 40 sccm and a pressure of about 40 Pa, and at about 8.33 mW / cm ² To form a non-doped amorphous silicon film 2a having a thickness of about 5 nm to about 20 nm on the upper surface of the n-type single crystal silicon substrate 1. In this case, the interface between the n-type single-crystal silicon substrate 1 and the non-doped amorphous silicon film 2a has an amount of hydrogen atoms capable of inactivating crystal defects near the upper surface of the n-type single-crystal silicon substrate 1. (Hydrogen atom surface density: about 1.9 × 10 ^Fifteen cm ^-2 ) Is introduced.
[0033]
In the process of forming the non-doped amorphous silicon film 2a, if the gas is replaced by high vacuum evacuation after the hydrogen treatment, the hydrogen atom surface density is reduced. In particular, when high vacuum evacuation is performed for about 1 minute or more, the hydrogen atom surface density becomes almost the same as that without hydrogen treatment. This means that the hydrogen atoms supplied to the upper surface of the n-type single-crystal silicon substrate 1 by the hydrogen treatment are not necessarily driven into the n-type single-crystal silicon substrate 1 to form a stable covalent bond. This suggests that the substrate is in an unstable state adsorbed on the upper surface of the single-crystal silicon substrate 1 and its vicinity. Therefore, in controlling the hydrogen atom surface density at the interface between the n-type single-crystal silicon substrate 1 and the non-doped amorphous silicon film 2a, the upper surface of the n-type single-crystal silicon substrate 1 is subjected to hydrogen treatment, It is important to form the non-doped amorphous silicon film 2a continuously without replacing the gas by the gas.
[0034]
Subsequently, while maintaining the substrate temperature at about 170 ° C., the SiH ₄ Gas flow rate: about 40 sccm, hydrogen gas flow rate: 0 to about 100 sccm, diborane (B ₂ H ₆ ) / H ₂ (H ₂ B for ₂ H ₆ Gas concentration: about 2%) Gas flow rate: about 40 sccm, pressure: about 40 Pa, and power density: about 8.33 mW / cm ² Under the above conditions, a p-type amorphous silicon film 2b doped with boron (B) having a thickness of about 3 nm to about 10 nm is formed on the non-doped amorphous silicon film 2a.
[0035]
Next, as shown in FIG. 5, a surface electrode 3 made of ITO (indium tin oxide) having a thickness of about 70 nm to about 100 nm is formed on the upper surface of the p-type amorphous silicon film 2b by a sputtering method. Form. Thereafter, a collector electrode 4 made of silver having a thickness of several tens of μm is formed in a predetermined region on the front surface electrode 3 by using a screen printing method.
[0036]
Next, the same hydrogen treatment as the above-described hydrogen treatment on the upper surface of the n-type single-crystal silicon substrate 1 is performed on the back surface of the n-type single-crystal silicon substrate 1. However, the hydrogen gas in this case is introduced at a flow rate of about 100 sccm and a pressure of about 50 Pa.
[0037]
Thereafter, as shown in FIG. 1, a non-doped amorphous silicon film 12a is formed on the back surface of the n-type single crystal silicon substrate 1 by using a plasma CVD method. Specifically, while maintaining the substrate temperature at about 170 ° C., the SiH ₄ A gas is introduced at a flow rate of about 40 sccm and a pressure of about 40 Pa, and at a rate of about 8.33 mW / cm ² To form a non-doped amorphous silicon film 12a having a thickness of about 5 nm to about 40 nm on the back surface of the n-type single crystal silicon substrate 1. Subsequently, while maintaining the substrate temperature at about 170 ° C., the SiH ₄ Gas flow rate: about 40 sccm, hydrogen gas flow rate: 0 to about 100 sccm, phosphine (PH ₃ ) / H ₂ (H ₂ PH against ₃ Gas concentration: about 40 sccm, pressure: about 40 Pa, and power density: 8.33 mW / cm. ² Under the conditions described above, an n-type amorphous silicon film 12b doped with phosphorus (P) having a thickness of about 5 nm to about 40 nm is formed on the back surface of the non-doped amorphous silicon film 12a.
[0038]
Finally, a back electrode 13 made of ITO having a thickness of about 70 nm to about 100 nm is formed on the back surface of the n-type amorphous silicon film 12b by using a sputtering method. A collector electrode 14 made of silver having a thickness of several tens of μm is formed. Thus, the photovoltaic device according to the first embodiment shown in FIG. 1 is formed.
[0039]
In the first embodiment, as described above, the hydrogen atom concentration at the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a (about 6 × 10 ²¹ cm ^-3 ) Is made higher than the hydrogen atom concentration in the non-doped amorphous silicon film 2a, and the hydrogen atom surface density at the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a is set to about 1.9. × 10 ^Fifteen cm ^-2 By doing so, the amount of hydrogen atoms at the interface between the n-type single-crystal silicon substrate 1 and the non-doped amorphous silicon film 2a is larger than the amount of hydrogen atoms in the non-doped amorphous silicon film 2a. The increased hydrogen atoms can terminate and inactivate dangling bonds of silicon atoms, which are crystal defects near the upper surface of the n-type single crystal silicon substrate 1. Thereby, crystal defects near the upper surface of n-type single crystal silicon substrate 1 can be reduced, so that capture of carriers by the crystal defects can be suppressed. As a result, recombination of carriers near the upper surface of the n-type single crystal silicon substrate 1 can be suppressed, so that the output characteristics of the photovoltaic device can be improved. Further, dangling bonds of silicon atoms are terminated by hydrogen atoms, so that the coordination number of silicon atoms is reduced. As a result, the flexibility of silicon atoms is increased, so that the generation of new dangling bonds of silicon atoms, which are crystal defects, can be suppressed.
[0040]
Next, an experiment performed to confirm the effect of introducing hydrogen atoms to the interface between the n-type single-crystal silicon substrate 1 and the non-doped amorphous silicon film 2a will be described. Specifically, in order to investigate the characteristics of the photovoltaic device due to the difference in the hydrogen atom surface density at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film, six light sources having different hydrogen atom surface densities were used. Open voltage V of electromotive force device _OC , Short-circuit current I _SC , Fill factor F. F and cell output P _max Was measured. The results are shown in Table 1 below, and the hydrogen atom surface density and cell output P in Table 1 are shown. _max Is shown in FIG. The open-circuit voltage V in Table 1 _OC Is the voltage measured when light is applied to the photovoltaic device, which is measured by connecting a voltmeter between the front and back electrodes, and is the output voltage value when no current is flowing. is there. In addition, the short-circuit current I _SC Is the current measured by connecting an ammeter between the front and rear electrodes of the photovoltaic device when the light is applied to the photovoltaic device. Value. Also, cell output P _max Is the voltage V when the maximum resistance is obtained by changing the load resistance when the load resistance is connected to the photovoltaic device. _m And the current I _m Is the product of The fill factor F. F is the cell output P _max Is the open circuit voltage V _OC And short-circuit current I _SC And the product of the fill factor F. As the value of F approaches 1, the current-voltage characteristics of the photovoltaic device are more excellent.
[0041]
[Table 1]

Referring to Table 1 above, the hydrogen atom areal densities at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film of each of the six photovoltaic devices were about 5.3 × 10 ^Thirteen cm ^-2 , About 1.2 × 10 ¹⁴ cm ^-2 , About 2.5 × 10 ¹⁴ cm ^-2 , About 1.9 × 10 ^Fifteen cm ^-2 (Corresponding to the first embodiment), about 2.1 × 10 ¹⁶ cm ^-2 And about 1.3 × 10 ¹⁷ cm ^-2 And The hydrogen atom surface density at the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film controls the flow rate of hydrogen gas when the upper surface of the n-type single-crystal silicon substrate is subjected to hydrogen treatment in the above-described manufacturing process. Is controlled by Incidentally, the hydrogen atom surface density is about 5.3 × 10 ^Thirteen cm ^-2 In the photovoltaic device in the case of (1), no hydrogen treatment is performed. This hydrogen atom surface density is about 5.3 × 10 ^Thirteen cm ^-2 In the case of (1), the silane (SiH ₄ It is considered that the hydrogen contained in ()) was introduced at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film.
[0042]
Referring to Table 1 and FIG. 6, the hydrogen atom area density is about 1.2 × 10 ¹⁴ cm ^-2 ~ About 2.1 × 10 ¹⁶ cm ^-2 Open voltage V in case of _OC Is about 0.671 V to about 0.708 V, and the hydrogen atom surface density without hydrogen treatment is about 5.3 × 10 ^Thirteen cm ^-2 Open voltage V in case of _OC (About 0.665 V). Further, the hydrogen atom surface density is about 1.2 × 10 ¹⁴ cm ^-2 ~ About 2.1 × 10 ¹⁶ cm ^-2 The fill factor F. F is about 0.757 to about 0.765, and the hydrogen atom surface density without hydrogen treatment is about 5.3 × 10 ^Thirteen cm ^-2 The fill factor F. It turned out to be closer to 1 than F (about 0.731). Further, the hydrogen atom surface density is about 1.2 × 10 ¹⁴ cm ^-2 ~ About 2.1 × 10 ¹⁶ cm ^-2 Cell output P in case _max Is about 1.875 W to about 2.016 W, and the hydrogen atom areal density of about 5.3 × 10 ^Thirteen cm ^-2 Cell output P in case _max (About 1.81 W). Thereby, when the hydrogen treatment is performed, and the hydrogen atom surface density is about 1.2 × 10 ¹⁴ cm ^-2 ~ About 2.1 × 10 ¹⁶ cm ^-2 In the range, it is considered that a crystal defect is inactivated by a hydrogen atom.
[0043]
On the other hand, even when the hydrogen treatment is performed, the hydrogen atom surface density is about 1.3 × 10 ¹⁷ cm ^-2 Is too high, the open circuit voltage V _OC Is about 0.648V and the cell output P _max Is about 1.777 W, and the hydrogen atom areal density of about 5.3 × 10 ^Thirteen cm ^-2 Open-circuit voltage V _OC And cell output P _max Was found to decrease. This is because during the hydrogen treatment, the ion energy of hydrogen increases due to an increase in the amount of hydrogen atoms, and as a result, defects are generated by irradiating the surface of the n-type single crystal silicon substrate with hydrogen ions. It is believed that there is.
[0044]
According to the results shown in Table 1 and FIG. 6, the hydrogen atom surface density at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film is about 1.2 × 10 ¹⁴ cm ^-2 About 2.1 × 10 ¹⁶ cm ^-2 In the following cases, the open-circuit voltage V _OC , Fill factor F. F and cell output P _max Can be improved. Therefore, in the above-described first embodiment, the hydrogen atom surface density at the interface between the n-type single crystal silicon substrate 1 and the non-doped amorphous silicon film 2a is set to about 1.9 × 10 ^Fifteen cm ^-2 , The open-circuit voltage V _OC , Fill factor F. F and cell output P _max Can be improved.
[0045]
(2nd Embodiment)
In the second embodiment, unlike the first embodiment, in order to inactivate defects, fluorine atoms are added to the n-type single-crystal silicon substrate, the non-doped amorphous silicon film, and the n-type single-crystal silicon. An example in the case where the light is introduced near the interface between the substrate and the non-doped amorphous silicon film will be described. That is, in the photovoltaic device according to the second embodiment, fluorine atoms are introduced by treating the n-type single-crystal silicon substrate with hydrofluoric acid during the step of cleaning the n-type single-crystal silicon substrate at the beginning of the manufacturing process. I do.
[0046]
Specifically, in the second embodiment, in the step of cleaning the n-type single-crystal silicon substrate, hydrofluoric acid (HF / H ₂ O) (about 3 mol / l to about 10 mol / l HF content, room temperature) ₂ Perform an O rinse (room temperature, about 10 seconds to about 10 minutes). As a result, the surface of the n-type single crystal silicon substrate ₂ A residue of hydrofluoric acid not removed by O-rinsing remains. The above-mentioned hydrofluoric acid (HF / H ₂ O) concentration and H ₂ By changing the rinsing time of the O-rinse, the amount of the introduced fluorine atoms can be controlled. For example, when the concentration of hydrofluoric acid is increased, the amount of introduced fluorine atoms increases. Also, H ₂ If the rinsing time of the O-rinse is shortened, the residual amount of hydrofluoric acid increases, so that the amount of the introduced fluorine atoms increases.
[0047]
In the second embodiment, the hydrogen treatment on the surface of the n-type single-crystal silicon substrate as in the first embodiment is not performed. The structure and manufacturing process of the other parts of the second embodiment are the same as those of the first embodiment.
[0048]
In the second embodiment, the hydrofluoric acid treatment and H ₂ An amount of fluorine atoms (fluorine atoms) capable of inactivating crystal defects near the upper surface of the n-type single-crystal silicon substrate is provided at the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film by O-rinsing. Area density: about 1.5 × 10 ¹² cm ^-2 ) Is introduced. Further, fluorine atoms introduced at the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film diffuse into the n-type single-crystal silicon substrate and the non-doped amorphous silicon film, so that Fluorine atoms are introduced into the crystalline silicon substrate and into the non-doped amorphous silicon film.
[0049]
FIG. 7 shows a concentration profile diagram of fluorine atoms near the upper surface of the n-type single crystal silicon substrate measured by SIMS of the photovoltaic device according to the second embodiment and the photovoltaic device according to the comparative example. For the measurement of the concentration profile of the fluorine atom (F), SIMS (ADEPT 1010) manufactured by Physical electronic Incorporation was used. The measurement conditions at this time are irradiation ion species: Cs ⁺ Ion, ion irradiation energy: 1 keV, irradiation angle: 60 °, secondary ion species detected: F ⁻ Ion, reference secondary ion species: Si ⁻ It was an ion. In the measurement by SIMS, the photovoltaic device has Cs ⁺ The secondary ions (F ⁻ Ions and Si ⁻ Ion) and the number of Si ⁻ Number of ions [Si ⁻ F for ⁻ Number of ions [F ⁻ ] ([F ⁻ ] / [Si ⁻ ] Except that [Si ⁻ ] = 5.0 × 10 ²² / Cm ³ ), The concentration of fluorine atoms is determined.
[0050]
Here, in the photovoltaic device according to the second embodiment, the above-mentioned HF content of about 3 mol / l to about 10 mol / l is treated with hydrofluoric acid at room temperature, and is treated at room temperature for about 10 seconds to about 10 minutes. ₂ After O-rinsing, the silane (SiH ₄ ) Gas is introduced at a flow rate of about 40 sccm and a pressure of about 40 Pa, and at about 8.33 mW / cm ² By applying the above power, a non-doped amorphous silicon film having a thickness of about 5 nm to about 20 nm was formed on the upper surface of the n-type single crystal silicon substrate. That is, in the second embodiment, fluorine is introduced before the formation of the non-doped amorphous silicon film, and fluorine is not introduced during the formation of the non-doped amorphous silicon film. On the other hand, in the photovoltaic device according to the comparative example, the above-mentioned HF content of about 3 mol / l to about 10 mol / l is treated with hydrofluoric acid at room temperature and H for 10 seconds to about 10 minutes at room temperature. ₂ After performing the O-rinsing, the fluorine (F) / silane (SiH ₄ ) (SiH ₄ Concentration of F with respect to the gas: kept constant at about 0.2%) The gas is introduced at a flow rate of about 40 sccm and at a pressure of about 40 Pa, and at about 8.33 mW / cm ² By applying the above power, a non-doped amorphous silicon film having a thickness of about 5 nm to about 20 nm was formed on the upper surface of the n-type single crystal silicon substrate. That is, in the comparative example, fluorine is introduced not only before the formation of the non-doped amorphous silicon film but also during the formation of the non-doped amorphous silicon film. Except for this, the photovoltaic device according to the comparative example was manufactured in the same manner as in the second embodiment.
[0051]
Referring to FIG. 7, in the second embodiment, the peak of the fluorine atom concentration is located near the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film. 0x10 ¹⁹ cm ^-3 It can be seen that it is. In the second embodiment, as in the first embodiment, the fluorine at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film is removed in order to eliminate the dependence of the SIMS measurement data on the measurement conditions. The amount of atoms is defined by the areal density obtained by integrating the peak concentration of fluorine atoms in the depth direction. That is, the fluorine atom surface density at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film is the integral value of the curve shown by the broken line in FIG. 7 (the area of the hatched portion in FIG. 7), About 1.5 × 10 ¹² cm ^-2 It is.
[0052]
In the comparative example, the region from the n-type single-crystal silicon substrate to the vicinity of the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film shows the same fluorine atom concentration profile as in the second embodiment. You can see that. On the other hand, unlike the second embodiment, the comparative example does not have a fluorine atom concentration peak near the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film. Specifically, the photovoltaic device according to the comparative example is substantially constant in the region from the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film to the non-doped amorphous silicon film, and A fluorine atom concentration larger than that of the second embodiment (about 1.0 × 10 ¹⁹ cm ^-3 ).
[0053]
In the second embodiment, the concentration profile as shown in FIG. 7 was obtained in the vicinity of the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film by hydrofluoric acid treatment of the surface of the n-type single-crystal silicon substrate. This is considered to be because a region having a large amount of fluorine atoms was formed in the region. On the other hand, in the comparative example, the concentration profile as shown in FIG. 7 was obtained because, in addition to the hydrofluoric acid treatment, a non-doped amorphous It is considered that the formation of the silicon film introduced a substantially uniform amount of fluorine atoms over the thickness direction of the non-doped amorphous silicon film and more fluorine atoms than in the second embodiment.
[0054]
In the second embodiment, as described above, the introduced fluorine atoms are introduced into the n-type single crystal silicon substrate and the non-doped amorphous silicon film by introducing the fluorine atoms capable of inactivating defects. The dangling bonds can be inactivated by bonding with the dangling bonds of silicon atoms which are defects in the n-type single crystal silicon substrate and the non-doped amorphous silicon film. Accordingly, defects in the n-type single crystal silicon substrate and the non-doped amorphous silicon film can be reduced, so that carriers can be suppressed from being captured by the defects. Therefore, recombination of carriers in the n-type single crystal silicon substrate and the non-doped amorphous silicon film can be suppressed. Also, the peak of the concentration of the introduced fluorine atoms (peak concentration: about 1.0 × 10 ¹⁹ cm ^-3 ) Is located near the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film, and has a fluorine atom surface density of about 1.5 at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film. × 10 ¹² cm ^-2 By doing so, the amount of fluorine atoms at the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film increases, and the increased fluorine atoms cause crystal defects near the upper surface of the n-type single-crystal silicon substrate. Certain dangling bonds can be terminated and deactivated. Thus, crystal defects can be reduced in the vicinity of the upper surface of the n-type single crystal silicon substrate, so that capture of carriers by the crystal defects can be suppressed. Therefore, recombination of carriers near the upper surface of the n-type single crystal silicon substrate can be suppressed. In this manner, recombination of carriers in the n-type single-crystal silicon substrate, in the non-doped amorphous silicon film, and near the upper surface of the n-type single-crystal silicon substrate can be suppressed. Characteristics can be improved.
[0055]
Further, unlike the comparative example, the second embodiment is configured such that the peak of the concentration of fluorine atoms is located near the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film, so that the n-type It is possible to suppress the amount of fluorine atoms in the non-doped amorphous silicon film from becoming larger than the amount of fluorine atoms near the interface between the crystalline silicon substrate and the non-doped amorphous silicon film. Accordingly, it is possible to suppress a decrease in film characteristics such as the denseness of the non-doped amorphous silicon film due to the introduction of many fluorine atoms into the non-doped amorphous silicon film. For this reason, it is possible to suppress a decrease in the output characteristics of the photovoltaic device due to a decrease in the film characteristics of the non-doped amorphous silicon film.
[0056]
In the second embodiment, the introduced fluorine atoms bond with the dangling bonds of the silicon atoms, so that the coordination number of the silicon atoms is reduced. As a result, the flexibility of silicon atoms is increased, so that the generation of new dangling bonds of silicon atoms, which are crystal defects, can be suppressed.
[0057]
Next, an experiment in which the output characteristics of the photovoltaic device are actually measured in order to confirm the effects of the above-described second embodiment will be described. Specifically, a photovoltaic device having a fluorine atom concentration profile as in the second embodiment of FIG. 7 (Example 1), and a light having a fluorine atom concentration profile as in the comparative example of FIG. Output characteristics (open-circuit voltage V) of electromotive force device (Comparative Example 1) _oc , Short-circuit current I _sc , Fill factor F. F and cell output P _max ) Was measured. Then, the open-circuit voltage V of Comparative Example 1 with respect to Example 1 _oc , Short-circuit current I _sc , Fill factor F. F and cell output P _max Were calculated. The results are shown in Table 2 below.
[0058]
[Table 2]

Referring to Table 2 above, the ratio of the output characteristics of Comparative Example 1 to Example 1 (open circuit voltage V _oc : 0.995, short-circuit current I _sc : 1.001, fill factor F. F: 0.993 and cell output P _max : 0.989) is the short-circuit current I _sc It can be seen that except for, it is smaller than 1. Thus, in the first embodiment, the short-circuit current I _sc Output characteristics (open circuit voltage V _oc , Fill factor F. F and cell output P _max ) Is improved. This is because, in Comparative Example 1, since more fluorine atoms were introduced into the non-doped amorphous silicon film than in Example 1, the film properties such as the denseness of the non-doped amorphous silicon film deteriorated. It is considered that the output characteristics were degraded.
[0059]
Next, the cell output P of the photovoltaic device due to the difference in the fluorine atom surface density at the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film. _max To determine the cell output P of the photovoltaic devices with different fluorine atom areal densities _max Was measured. The measurement result will be described with reference to FIG. In FIG. 8, the cell output P of each photovoltaic device is shown. _max Has a fluorine atom area density of 1.0 × 10 ¹² cm ^-2 Cell output P when _max Are standardized as cell output standard values.
[0060]
Referring to FIG. 8, the fluorine atom surface density at the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film is 1.0 × 10 ⁹ cm ^-2 As the cell output increases, the cell output increases, and the fluorine atom area density becomes 1.0 × 10 ¹² cm ^-2 It can be seen that the cell output becomes maximum in the vicinity. Further, the fluorine atom area density is 1.0 × 10 ¹² cm ^-2 It is understood that the cell output becomes smaller when the value exceeds. Fluorine atom area density 1.0 × 10 ¹² cm ^-2 The cell output increased in the range up to the vicinity because the crystal defects near the upper surface of the n-type single-crystal silicon substrate increased with the increase of fluorine atoms at the interface between the n-type single-crystal silicon substrate and the non-doped amorphous silicon film. It is considered that the dangling bond of the silicon atom is more inactivated. Further, the fluorine atom area density is 1.0 × 10 ¹² cm ^-2 It is considered that the reason why the cell output decreases when the value exceeds the vicinity is that the amount of fluorine atoms introduced into the interface between the n-type single crystal silicon substrate and the non-doped amorphous silicon film becomes excessive. More specifically, if the amount of fluorine atoms (F) is excessive, an FF bond having a small binding energy (bonding force) is generated. This is probably because dangling bonds, which are crystal defects near the upper surface of the substrate, increase.
[0061]
Referring to FIG. 8, the fluorine atom area density is 1.0 × 10 ¹⁰ cm ^-2 1.0 × 10 or more ¹⁴ cm ^-2 It can be seen that in the following range, the standard value of the cell output is 0.8 or more. It has been confirmed by the present inventor that a photovoltaic device having a fluorine atom surface density in this range can obtain good output characteristics. Further, the fluorine atom area density is 5.0 × 10 ¹⁰ cm ^-2 2.0 × 10 or more ^Thirteen cm ^-2 It can be seen that in the following range, the standard value of the cell output is 0.9 or more. It has been confirmed by the present inventor that a photovoltaic device having a fluorine atom surface density in this range can obtain better output characteristics.
[0062]
It should be noted that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and includes all modifications within the scope and meaning equivalent to the terms of the claims.
[0063]
For example, in the above embodiment, the p-type amorphous silicon film 2b is formed on the upper surface of the n-type single crystal silicon substrate 1 via the substantially intrinsic non-doped amorphous silicon film 2a. The present invention is not limited to this, and an n-type amorphous silicon film may be formed on the upper surface of a p-type single crystal silicon substrate via a substantially intrinsic non-doped amorphous silicon film.
[0064]
In the above embodiment, the BSF structure in which the amorphous silicon film 12 (the non-doped amorphous silicon film 12a and the n-type amorphous silicon film 12b) is formed on the back surface of the n-type single crystal silicon substrate 1 is used. However, the present invention is not limited to this, and a back surface electrode may be formed on the back surface of the n-type single crystal silicon substrate without forming the n-side amorphous silicon film.
[0065]
In the above embodiment, the p-side film is formed first, but the present invention is not limited to this, and the n-side film may be formed first.
[0066]
In the above embodiment, the substantially intrinsic non-doped amorphous silicon film 2a is provided between the n-type single crystal silicon substrate 1 and the p-type amorphous silicon film 2b (n-type amorphous silicon film 12b). (Non-doped amorphous silicon film 12a) is formed, but the present invention is not limited to this, and a substantially non-doped amorphous silicon film is formed between the first conductive type crystalline semiconductor and the second conductive type amorphous semiconductor film. It is not necessary to form an intrinsic non-doped amorphous silicon film.
[0067]
In the above embodiment, hydrogen atoms and fluorine atoms are used as impurities for inactivating defects near the upper surface of the n-type single-crystal silicon substrate, in the n-type single-crystal silicon substrate, and in the non-doped amorphous silicon film. Although the introduction example has been described, the present invention is not limited to this, and other atoms may be introduced. For example, the same effect can be obtained by introducing a chlorine atom or the like.
[0068]
Further, in the above-described embodiment, an example in which the present invention is applied to the p-side (front side) of the photovoltaic device has been described. The effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a structure of a photovoltaic device according to a first embodiment of the present invention.
FIG. 2 is a concentration profile diagram of hydrogen atoms near the upper surface of an n-type single crystal silicon substrate 1 of the photovoltaic device according to the first embodiment shown in FIG.
FIG. 3 is a cross-sectional view for explaining a manufacturing process of the photovoltaic device according to the first embodiment shown in FIG.
FIG. 4 is a cross-sectional view for explaining a manufacturing process of the photovoltaic device according to the first embodiment shown in FIG.
FIG. 5 is a cross-sectional view for explaining a manufacturing process of the photovoltaic device according to the first embodiment shown in FIG.
FIG. 6: Hydrogen atomic surface density and cell output P _max 6 is a graph showing a relationship with the graph.
FIG. 7 is a concentration profile diagram of fluorine atoms near the upper surface of an n-type single crystal silicon substrate measured by SIMS of a photovoltaic device according to a second embodiment of the present invention and a photovoltaic device according to a comparative example.
FIG. 8 is a diagram showing the relationship between the fluorine atom surface density at the interface between an n-type single crystal silicon substrate and a non-doped amorphous silicon film and the cell output.
[Explanation of symbols]
1 n-type single crystal silicon substrate (crystalline semiconductor)
2,12 amorphous silicon film
2a, 12a Non-doped amorphous silicon film (amorphous semiconductor film, first amorphous semiconductor film)
2bp p-type amorphous silicon film (amorphous semiconductor film, second amorphous semiconductor film)
12b n-type amorphous silicon film (amorphous semiconductor film, second amorphous semiconductor film)

Claims (11)

A crystalline semiconductor;
An amorphous semiconductor film formed on the surface of the crystalline semiconductor,
A photovoltaic device, wherein a hydrogen atom concentration at an interface between the crystalline semiconductor and the amorphous semiconductor film is higher than a hydrogen atom concentration in the amorphous semiconductor film. 2. The method according to claim 1, wherein an amount of hydrogen atoms capable of inactivating a crystal defect near a surface of the crystalline semiconductor is introduced into an interface between the crystalline semiconductor and the amorphous semiconductor film. 3. The photovoltaic device according to any of the preceding claims. The hydrogen atom surface density at an interface between the crystalline semiconductor and the amorphous semiconductor film is 1.2 × 10 ¹⁴ cm ⁻² or more and 2.1 × 10 ¹⁶ cm ⁻² or less. The photovoltaic device according to any of the preceding claims. The hydrogen atom concentration at the interface between the crystalline semiconductor and the amorphous semiconductor film is higher than the hydrogen atom concentration in the crystalline semiconductor, and the hydrogen atom concentration in the crystalline semiconductor is The photovoltaic device according to any one of claims 1 to 3, wherein the photovoltaic device is lower than a hydrogen atom concentration in the semiconductor film. The amorphous semiconductor film,
A substantially intrinsic first amorphous semiconductor film formed on the surface of the crystalline semiconductor;
5. The photovoltaic device according to claim 1, further comprising: a first conductive type second amorphous semiconductor film formed on a surface of the first amorphous semiconductor film. 6. A crystalline semiconductor;
An amorphous semiconductor film formed on the surface of the crystalline semiconductor,
An impurity capable of inactivating a defect is introduced into the crystalline semiconductor and the amorphous semiconductor film, and a peak of the impurity concentration is reduced between the crystalline semiconductor and the amorphous semiconductor film. A photovoltaic device located near the interface with. The photovoltaic device according to claim 6, wherein the impurity is one of a hydrogen atom and a fluorine atom. 8. The method according to claim 7, wherein an amount of fluorine atoms capable of inactivating a crystal defect near a surface of the crystalline semiconductor is introduced into an interface between the crystalline semiconductor and the amorphous semiconductor film. The photovoltaic device according to any of the preceding claims. The photovoltaic device according to claim 7, wherein a fluorine atom surface density at an interface between the crystalline semiconductor and the amorphous semiconductor film is from 1 × 10 ¹⁰ cm ^{−2 to} 1 × 10 ¹⁴ cm ^−2. Power equipment. The photovoltaic device according to claim 9, wherein a fluorine atom surface density at an interface between the crystalline semiconductor and the amorphous semiconductor film is 5 × 10 ¹⁰ cm ⁻² or more and 2 × 10 ¹³ cm ⁻² or less. . Hydrotreating the surface of the crystalline semiconductor with a predetermined flow rate of hydrogen gas,
Forming a non-crystalline semiconductor film on the surface of the crystalline semiconductor without replacing the gas by high vacuum evacuation.

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