JP2004071715A - Photovoltaic element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photovoltaic element which has superior characteristics without causing damage to a transparent electrode or an amorphous n-type layer serving as the underlying layer of a microcrystal p-type layer. <P>SOLUTION: A method of manufacturing the photovoltaic element 20 equipped with a cell 21 is performed as follows. Silicon-containing material gas and hydrogen gas are supplied between a substrate 25 and an electrode at the same time, high-frequency radio waves of 10 MHz to 300 MHz are applied to generate plasma gas for successively laminating a microcrystal p-type layer 13, a microcrystal i-type layer 14, and a microcrystal n-type layer 15, each formed of microcrystal silicon, on the front surface of a substrate 25 to form the cell 21. The microcrystal p-type layer 13 is formed through forming an initial layer of microcrystal silicon before forming a bulk layer 13b the use of a high-frequency power lower than that used for forming the bulk layer 13b, or at a substrate temperature lower than that when the bulk layer 13b is formed, or by the use of plasma gas which is higher in pressure than that when the bulk layer 13b is formed. <P>COPYRIGHT: (C)2004,JPO

Description

【００３６】
表１は、第一従来例の光起電力素子の光電変換効率を１．００とした相対値で示している。第一〜第三実施形態では、各々、初期層１３ａ製膜時の高周波電力、基板温度及び圧力を制御し、第一従来例と比し、下地層である透明電極１２に対して緩やかな製膜条件を設定したことが確認できる。すなわち、第一実施形態においては、高周波電力を第一従来例より小とし、第二実施形態においては、基板温度を第一従来例より小とし、第三実施形態においては、プラズマガスの圧力を第一従来例より大としたところ、微結晶ｐ層１３形成時の透明電極１２の損傷発生が抑制され、透明電極１２の半導体特性低下の発生が抑制されるとともに、この損傷発生抑制効果により、下地層である透明電極１２から析出した元素等の微結晶ｐ層１３内への拡散侵入発生が抑制され、微結晶ｐ層１３の半導体特性低下の発生が抑制されたことから、光電変換効率が改善されたことが確認できる。第一〜第三実施形態では、第一従来例より１１％〜１５％改善されたことが確認できる。
【００３７】
次に、それぞれで初期層１３ａの膜厚のみを異ならせ、その他時間を除く製膜条件の全てを第一実施形態と同一として複数の光起電力素子２０を形成し、前述と同様にして、それぞれの光起電力素子２０について光電変換効率を計測した。すなわち、初期層１３ａの膜厚と、光電変換効率との関係を図４に示す。図４は、第一従来例の光起電力素子の変換効率を１．００とした相対値で示している。
【００３８】
図４において、初期層１３ａによる透明電極１２の損傷発生抑制効果が現れるのは、初期層１３ａの膜厚が５ｎｍ以上５０ｎｍ以下の範囲であり、特に、膜厚１５ｎｍ以上５０ｎｍ以下の場合に、その効果が顕著であることが確認できる。また、膜厚５０ｎｍを超えると、透明電極１２の損傷抑制効果は飽和するとともに、初期層１３ａでの光の吸収量が過多となり、光起電力素子としての短絡電流が低下し、光電変換効率が低下することが確認できる。
【００３９】
次に、本発明の第四実施形態について説明するが、前述の第一〜第三実施形態と同様の部位には、同一符号を付し、その説明を省略する。
本第四実施形態による光起電力素子２２は、図５に示すように、基板２５と、非晶質シリコン素子からなるトップセル２３と、微結晶シリコン素子からなるボトムセル２４と、裏面電極１６とを備え、これらが順次積層された構成となっている。トップセル２３は、ｐ型の非晶質シリコンである非晶質ｐ層１７と、ｉ型の非晶質シリコンである非晶質ｉ層１８と、ｎ型の非晶質シリコンである非晶質ｎ層１９とを備え、これらが順次積層された構成となっている。また、ボトムセル２４は、微結晶ｐ層１３と、微結晶ｉ層１４と、微結晶ｎ層１５とを備え、これらが順次積層された構成となっており、ボトムセル２４は、微結晶ｐ層１３を介してトップセル２３上に設けられるとともに、微結晶ｎ層１５上に裏面電極１６が設けられた構成となっている。ここで、微結晶ｐ層１３は、製膜の初期段階で透明電極１２表面に積層形成された初期層１３ａと、この初期層１３ａ表面に積層形成されたバルク層１３ｂとから構成されている。
【００４０】
ここで、非晶質ｐ層１７の膜厚は、５ｎｍ以上５０ｎｍ以下で形成されている。これは、非晶質ｐ層１７の膜厚が５ｎｍ未満の場合、部分的に透明電極１２が露出した状態、いわゆる島状成長となる。この場合に、非晶質ｐ層１７が製膜されていない部分は、正常な半導体ｐｎ接合が形成されないため、光起電力素子としての特性が著しく低下するからである。一方、非晶質ｐ層１７の膜厚が５０ｎｍを超える場合、基板２５側からの光の入射層である非晶質ｐ層１７での光の吸収量が過多となり、光電変換層である非晶質ｉ層１８及び微結晶ｉ層１４への入射光量が減少し、光起電力素子としての短絡電流が低下するからである。
【００４１】
また、非晶質ｉ層１８の膜厚は、１００ｎｍ以上５００ｎｍ以下で形成されている。これは、非晶質ｉ層１８の膜厚が１００ｎｍ未満の場合、入射する光を充分に吸収できないため、光起電力素子としての短絡電流が低下するからである。一方、非晶質ｉ層１８の膜厚が５００ｎｍを超える場合、吸収した光によって非晶質ｉ層１８の欠陥が増加する、いわゆるステブラーロンスキー効果により、光劣化が大きくなるからである。
【００４２】
また、非晶質ｎ層１９の膜厚は、５ｎｍ以上５０ｎｍ以下で形成されている。これは、非晶質ｎ層１９の膜厚が５ｎｍ未満の場合、部分的に非晶質ｉ層１８が露出した状態、いわゆる島状成長となる。この場合に、非晶質ｎ層１９が製膜されていない部分は、正常な半導体ｐｎ接合が形成されないため、光起電力素子としての特性が著しく低下するからである。一方、非晶質ｎ層１９の膜厚が５０ｎｍを超える場合、非晶質ｎ層１９での光の吸収量が過多となり、ボトムセル２４への入射光量が減少し、光起電力素子としての短絡電流が低下するからである。
【００４３】
以上のように構成された光起電力素子２２の製造方法について説明する。
まず、第一〜第三実施形態と同様にして、ガラス基板９と透明電極１２とからなる基板２５を形成する。次に、基板２５の透明電極１２形成面に、トップセル２３を形成する。すなわち、透明電極１２上にプラズマＣＶＤ法を施し、非晶質ｐ層１７、非晶質ｉ層１８及び非晶質ｎ層１９を順次積層形成する。ここで、プラズマＣＶＤ法に用いる原料ガスは、シランＳｉＨ_４あるいはジシランＳｉ_２Ｈ_６等の水素化珪素ガス、またはジクロロシラン、トリクロロシラン等のハロシラン系ガスを用い、このときの電源周波数は、１３．５６ＭＰａに設定する。非晶質ｐ層１７を製膜する場合は、ドーピングガスとして、ＩＩＩ族元素を含むＢ_２Ｈ_６、ＢＦ_３等を添加する。また、非晶質ｎ層１９を製膜する場合には、ドーピングガスとして、Ｖ族元素を含むＰＨ_３等を添加する。
【００４４】
次に、トップセル２３上にボトムセル２４を形成するに際し、微結晶ｐ層１３の初期層１３ａは、前述した実施形態で使用した同一の装置３０において、製膜条件を、高周波電力３０Ｗ、基板温度１６５℃、プラズマガスの圧力６６．５Ｐａにそれぞれ設定し、膜厚を１２ｎｍで形成した。次に、微結晶ｐ層１３のバルク層１３ｂは、初期層１３ａの製膜条件のうち高周波電力を７５Ｗに変更し、膜厚を２５ｎｍで形成した。以下、前述の実施形態と同様にして、微結晶ｉ層１４、微結晶ｎ層１５、アルミニウムＡｌからなる裏面電極１６を順次積層形成し、光起電力素子２２を形成する。
【００４５】
次に、本発明に係る第五実施形態として、微結晶ｐ層１３の初期層１３ａの第四実施形態における製膜条件のうち、基板温度を１５０℃に、高周波電力を７５Ｗにそれぞれ変更し、光起電力素子２２を形成した。さらに、第六実施形態として、第四実施形態における製膜条件のうち、プラズマガスの圧力を９９．８Ｐａに、高周波電力を７５Ｗにそれぞれ変更し、光起電力素子２２を形成した。また、第二従来例として、微結晶ｐ層１３の初期層１３ａを、第四〜第六実施形態における微結晶ｐ層１３のバルク層１３ｂの製膜条件と同一にして形成し、微結晶ｐ層１３が微結晶バルク層１３ｂのみからなる光起電力素子を併せて形成した。
【００４６】
以上のように形成された第四〜第六実施形態の光起電力素子２２及び前記従来の光起電力素子のガラス基板９側から、模擬太陽光（ＡＭ（通過空気量）１．５、１００ｍＷ／ｃｍ^２）を照射し、各々の光電変換効率を計測した。結果を表２に示す。
【００４７】
【表２】

【００４８】
表２は、第二従来例の光起電力素子の変換効率を１．００とした相対値で示している。第四〜第六実施形態では、各々、初期層１３ａ製膜時の高周波電力、基板温度及びプラズマガスの圧力を制御し、第二従来例と比し、下地層である非晶質ｎ層１９に対して緩やかな製膜条件を設定したことが確認できる。すなわち、初期層１３ａ製膜時において、第四実施形態においては、高周波電力を第二従来例より小とし、第五実施形態においては、基板温度を第二従来例より小とし、第六実施形態においては、プラズマガスの圧力を第二従来例より大としたところ、微結晶ｐ層１３製膜時の非晶質ｎ層１９の損傷発生が抑制され、非晶質ｎ層１９の半導体特性低下の発生が抑制されるとともに、この損傷発生抑制効果により、非晶質ｎ層１９から析出したリンＰの微結晶ｐ層１３内への拡散侵入発生が抑制され、微結晶ｐ層１３の半導体特性低下の発生が抑制されたことから、光電変換効率が改善されたことが確認できる。すなわち、第四〜第六実施形態では、第二従来例より１０％〜１２％改善されたことが確認できる。これにより、タンデム構造においても、微結晶ｐ層１３の初期層１３ａにより光電変換効率が改善されることが確認できる。
【００４９】
以上説明したように、第一〜第六実施形態による光起電力素子の製造方法及び光起電力素子によれば、微結晶ｐ層１３を形成するに際し、微結晶シリコンのバルク層１３ｂを形成する前に、予め、微結晶シリコンの初期層１３ａを、バルク層１３ｂを形成する際の高周波電力より低い高周波電力で、又は、バルク層１３ｂを形成する際の基板温度より低い基板温度で、又は、バルク層１３ｂを形成する際のプラズマガスの圧力より高い圧力で形成するため、微結晶ｐ層１３を形成する際の下地層、すなわち、透明電極１２又は非晶質ｎ層１９の損傷発生を抑制することができる。これにより、高い光電変換効率を有する光起電力素子を形成することができる。
【００５０】
また、初期層１３ａの厚さが、５ｎｍ以上５０ｎｍ以下であるため、微結晶ｐ層１３を形成する際の下地層、すなわち、透明電極１２又は非晶質ｎ層１９の損傷発生を抑制し、その半導体特性低下の発生を抑制することができる。また、この損傷発生抑制効果により、下地層から析出した元素等の微結晶ｐ層１３内への拡散進入を抑制でき、微結晶ｐ層１３の半導体特性低下の発生を抑制することができる。さらに、初期層１３ａでの光の吸収量を最適なものとすることができ、光起電力素子としての短絡電流の低下発生を効率的に抑制することができる。以上により、高い光電変換効率を有する光起電力素子を提供することができる。
【００５１】
なお、本発明の技術的範囲は上記実施の形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲において種々の変更を加えることが可能である。
【００５２】
【発明の効果】
以上の説明から明らかなように、本発明に係る光起電力素子の製造方法及び光起電力素子によれば、微結晶ｐ層を形成する際に、予め、下地層に対して低負荷な製膜条件で微結晶シリコンの初期層を形成しておき、その後、微結晶シリコンのバルク層を形成するため、微結晶ｐ層の下地層の損傷発生が抑制され、良好な光電変換特性を有する光起電力素子を形成することができる。
【図面の簡単な説明】
【図１】本発明に係る第一〜第三実施形態において、光起電力素子を示す断面図である。
【図２】本発明に係る光起電力素子の製造に用いた製造装置を示す概略図である。
【図３】図２に示す製造装置の電極を示す平面図である。
【図４】微結晶ｐ層の初期層の膜厚と光起電力素子の光電変換効率との関係を示す図である。
【図５】本発明に係る第四〜第六実施形態において、光起電力素子を示す断面図である。
【符号の説明】
１…真空容器
２…電極
３…排気管
４…高周波電源
５…インピーダンス整合器
６…原料ガス導入管
７…基板ヒータ
８…真空ポンプ
９…ガラス基板
１０…同軸ケーブル
１１…ガス混合箱
１２…透明電極
１３…微結晶ｐ層
１３ａ…初期層
１３ｂ…バルク層
１４…微結晶ｉ層
１５…微結晶ｎ層
１６…裏面電極
１７…非晶質ｐ層
１８…非晶質ｉ層
１９…非晶質ｎ層
２０、２２…光起電力素子
２１…セル
２３…トップセル
２４…ボトムセル（セル）
２５…基板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photovoltaic element manufactured by a plasma CVD method and applied to a solar cell, a sensor, or the like, and a method for manufacturing the same.
[0002]
[Prior art]
A typical example of a photovoltaic element using a silicon-based thin film is an amorphous silicon-based solar cell. Amorphous silicon is usually manufactured by a plasma CVD method using a silicon hydride gas such as silane or disilane as a source gas. In general, a high frequency power supply having a frequency of 13.56 MHz is most commonly used for generating plasma. Amorphous silicon is characterized in that it can be formed on an inexpensive substrate such as glass, metal, or plastic at a low temperature of 200 ° C. or lower, and that a large-area film can be formed. Taking advantage of this feature, amorphous silicon solar cells can be reduced in cost during mass production, and are being developed as being superior to bulk silicon solar cells.
[0003]
However, when the amorphous silicon-based solar cell is irradiated with light, a defect occurs in the i-layer, which is a photoelectric conversion layer, and a photodegradation phenomenon in which the photoelectric conversion efficiency is reduced by about 10% to 30% compared with the initial state. (The so-called Stepleronsky effect) is a major obstacle to practical application. Although various studies have been conducted energetically on the mechanism of the photodegradation phenomenon, it has not been completely elucidated, and at present, no drastic solution has been established.
[0004]
In contrast, in recent years, attempts have been reported to use microcrystalline silicon instead of amorphous silicon as the i-type photoelectric conversion layer (J. Meier et al., Mat. Res. Soc. Symp. Proc. Vo.420.P3 (1996)). According to this, a pin-type photovoltaic element is formed by a high-frequency plasma CVD method using a power supply in a VHF band at a frequency of 110 MHz, and it is reported that the pin-type photovoltaic element does not involve a photodegradation phenomenon such as amorphous silicon. . In addition, a photovoltaic element using microcrystalline silicon as a photoelectric conversion layer has a peak in a spectral sensitivity spectrum on a longer wavelength side as compared with a photovoltaic element using amorphous silicon, A so-called tandem type of stacked photovoltaic device in which porous silicon is used as a top cell and microcrystalline silicon is used as a photoelectric conversion layer in a bottom cell is also possible.
[0005]
As described above, the photovoltaic element using microcrystalline silicon has an advantage that a film can be formed by a plasma CVD method having a configuration basically similar to that of the related art, and there is no light deterioration phenomenon. Here, the microcrystalline silicon film means a film other than amorphous silicon, and includes a polycrystalline silicon film and a crystalline silicon film containing amorphous in the film. Normally, a so-called pin type is adopted in a photovoltaic element using a microcrystalline silicon layer as a photoelectric conversion layer. In this case, the p-layer and the n-layer use microcrystalline silicon similarly to the i-layer. Photovoltaic elements using a microcrystalline silicon layer can be roughly classified into a substrate type and a superstrate type based on their structures.
[0006]
The substrate type element is configured using a substrate having no light transmission property, for example, a substrate such as stainless steel. On the other hand, the superstrate type element is formed on a substrate having light transmissivity represented by glass. In the case of a super-straight element, an integrated module similar to amorphous silicon can be constructed, but the substrate side, that is, the electrode on the light incident side, is required to have both characteristics of light transmission and electrical conductivity. , Generally, ITO, tin oxide SnO ₂ A transparent electrode made of a metal oxide such as zinc oxide or ZnO is used. In order to promote microcrystallization of the p layer in contact with the transparent electrode, high-density hydrogen radicals are generated, dangling bonds on the growth surface are terminated, and surface diffusion of silicon-based radicals involved in film formation is reduced. It is essential to promote.
[0007]
[Problems to be solved by the invention]
However, under such microcrystallization conditions for the p-layer, the transparent electrode composed of a metal oxide may be damaged, leading to a reduction in light transmittance and electrical conductivity of the transparent electrode. In such a case, there is a problem that the metal oxide is reduced by hydrogen radicals, and as a result, the deposited metal diffuses and enters the microcrystalline p-layer, thereby significantly lowering the semiconductor characteristics as the microcrystalline p-layer.
[0008]
In the case of a tandem structure in which an amorphous silicon-based element and a microcrystalline silicon-based element are stacked in the film thickness direction, the amorphous n-layer is basically in contact with the microcrystalline p-layer. In this case, to promote microcrystallization of the microcrystalline p-layer, dangling bonds on the growth surface are terminated, and high-density hydrogen radicals are generated for the purpose of promoting surface diffusion of radicals involved in film formation. There is a problem in that the amorphous n-layer, which is the underlayer of the microcrystalline p-layer, is etched by hydrogen radicals, which impairs the characteristics of the amorphous n-layer. Further, there is a problem that the V element, typically phosphorus, which is a dopant of the amorphous n-layer, diffuses into the microcrystalline p-layer and impairs the semiconductor characteristics of the microcrystalline p-layer.
[0009]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a light-emitting device having good characteristics without damaging a transparent electrode or an amorphous n-layer which is a base layer of a microcrystalline p-layer. It is to provide an electromotive element.
[0010]
[Means for Solving the Problems]
In order to solve the above problems and achieve such an object, the present invention proposes the following means.
The method for manufacturing a photovoltaic device of the present invention comprises simultaneously supplying a source gas containing silicon and a hydrogen gas between a substrate and an electrode, applying a high frequency of 10 MHz to 300 MHz to generate a plasma gas, A method for manufacturing a photovoltaic device having a cell in which a microcrystalline p-layer, a microcrystalline i-layer, and a microcrystalline n-layer made of microcrystalline silicon are sequentially stacked on a substrate surface side, wherein the microcrystalline p-layer Is characterized in that, before forming a bulk layer of microcrystalline silicon, an initial layer of microcrystalline silicon is formed in advance at a high frequency power lower than the high frequency power at the time of forming the bulk layer.
[0011]
In the method for manufacturing a photovoltaic device of the present invention, a source gas containing silicon and a hydrogen gas are simultaneously supplied between a substrate and an electrode, and a plasma gas is generated by applying a high frequency of 10 MHz to 300 MHz. A method of manufacturing a photovoltaic element having a cell in which a microcrystalline p-layer, a microcrystalline i-layer, and a microcrystalline n-layer made of microcrystalline silicon are sequentially stacked on the substrate surface side; In forming the p-layer, before forming the bulk layer of microcrystalline silicon, an initial layer of microcrystalline silicon is formed at a substrate temperature lower than the substrate temperature at which the bulk layer is formed. I do.
[0012]
In the method for manufacturing a photovoltaic device of the present invention, a source gas containing silicon and a hydrogen gas are simultaneously supplied between a substrate and an electrode, and a plasma gas is generated by applying a high frequency of 10 MHz to 300 MHz. A method of manufacturing a photovoltaic element having a cell in which a microcrystalline p-layer, a microcrystalline i-layer, and a microcrystalline n-layer made of microcrystalline silicon are sequentially stacked on the substrate surface side; In forming the p-layer, before forming the bulk layer of microcrystalline silicon, it is necessary to form an initial layer of microcrystalline silicon at a higher pressure than the pressure of the plasma gas when forming the bulk layer. Features.
[0013]
A photovoltaic device according to the present invention is manufactured by the method for manufacturing a photovoltaic device according to any one of claims 1 to 4.
[0014]
In the photovoltaic element manufacturing method and the photovoltaic element, when forming the microcrystalline p-layer, before forming the microcrystalline silicon bulk layer, the high-frequency power is lower than the high-frequency power when forming the bulk layer in advance. To form an initial layer of microcrystalline silicon at high frequency power or at a substrate temperature lower than the substrate temperature at which this bulk layer is formed, or at a pressure higher than the plasma gas pressure at the time of forming this bulk layer In addition, it is possible to suppress the occurrence of damage to the underlying layer when the microcrystalline p-layer is formed, and to suppress the deterioration of the semiconductor characteristics. Further, the effect of suppressing the occurrence of damage can suppress the occurrence of diffusion and intrusion of elements and the like deposited from the underlayer into the microcrystalline p-layer, thereby suppressing a decrease in the semiconductor characteristics of the microcrystalline p-layer. it can. Thereby, a photovoltaic element having high photoelectric conversion efficiency can be formed.
[0015]
In the method for manufacturing a photovoltaic element according to the present invention, the thickness of the initial layer is set to 5 nm or more and 50 nm or less. The thickness is particularly preferably from 15 nm to 50 nm.
[0016]
In this method of manufacturing a photovoltaic element, the thickness of the initial layer is not less than 5 nm and not more than 50 nm. Can be suppressed. Further, the effect of suppressing the occurrence of damage can suppress the deterioration of the semiconductor characteristics of the microcrystalline p-layer such as elements precipitated from the underlayer. Further, the amount of light absorption in the initial layer can be optimized, and a decrease in short-circuit current as a photovoltaic element can be suppressed. As described above, a photovoltaic element having high photoelectric conversion efficiency can be provided.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of a photovoltaic element and a method for manufacturing the same according to the present invention will be described with reference to FIGS.
The photovoltaic element 20 shown in FIG. 1 has a substrate 9 made of glass, ITO, tin oxide SnO. ₂ Alternatively, a transparent electrode 12 made of a metal oxide such as zinc oxide ZnO, a cell 21 made of a microcrystalline silicon element, and a back electrode 16 are sequentially stacked. The cell 21 includes a microcrystalline p-layer 13 of p-type microcrystalline silicon, a microcrystalline i-layer 14 of i-type microcrystalline silicon, and a microcrystalline n-layer 15 of n-type microcrystalline silicon. It has a stacked configuration.
[0018]
As will be described later, the microcrystalline p-layer 13 is composed of an initial layer 13a of microcrystalline silicon laminated on the surface of the transparent electrode 12 at the initial stage of film formation, and a microcrystalline silicon layer laminated on the surface of the initial layer 13a. And a bulk layer 13b. The initial layer 13a has a high-frequency power lower than the high-frequency power when forming the bulk layer 13b, or a temperature lower than the temperature of the substrate 9 and the transparent electrode 12 when forming the bulk layer 13b, or It is formed at a pressure higher than the pressure of the plasma gas to be described later at the time of formation.
[0019]
The method for manufacturing the microcrystalline p-layer 13, the microcrystalline i-layer 14, and the microcrystalline n-layer 15, that is, the microcrystalline silicon layer in the photovoltaic element 20 configured as described above will be described with reference to FIGS. . First, a plasma CVD apparatus 30 used for manufacturing microcrystalline silicon will be described.
[0020]
The plasma CVD apparatus 30 shown in FIG. 2 includes a vacuum vessel 1 made of stainless steel, a gas mixing box 11, a substrate heater 7, an electrode 2 for discharging, and a vacuum pump 8. The substrate heater 7 includes a mechanism (not shown) for closely holding the substrate 9 so that the film forming surface is on the lower side. A temperature sensor (not shown) is attached to the substrate heater 7 so that the temperature of the substrate 9 is detected indirectly or directly. The temperature sensor is connected to an input section of a controller (not shown). When a temperature detection signal is input to the controller, the controller controls the amount of power supplied to the substrate heater 7 based on the signal.
[0021]
The electrode 2 is disposed so as to face the substrate heater 7, and is connected to the impedance matching device 5 and the high frequency power supply 4 via the coaxial cable 10. Further, the power supply line from the high-frequency power supply 4 to the electrode 2 is branched, and a multipoint power is supplied to a plurality of points of the electrode 2 via each branch line. Can be alleviated. Here, as shown in FIG. 3, the electrode 2 has a configuration in which a plurality of rods are arranged at substantially the same pitch in a rectangular frame in parallel with one set of sides of the frame. I have. That is, the electrode 2 has a configuration in which a stainless steel wire having a diameter of about 4 mm to 12 mm is arranged in a ladder shape, and has both characteristics of the capacitive coupling discharge and the inductive coupling discharge. Further, the electrode 2 has a wider opening and is more excellent in controllability of the flow of the raw material gas than the conventional parallel plate type electrode, and thus is suitable for uniform film formation. As described above, the electrode 2 has a very high degree of freedom in designing the cross-sectional shape of the wire, the interval between the wires, the power supply position, and the like. Therefore, the silicon-based thin film has a large area and is uniform as compared with the conventional parallel plate type electrode. The structure is suitable for film formation.
[0022]
In the plasma CVD apparatus 30 configured as described above, first, the substrate 9 that has been degreased and cleaned and dried is held in close contact with the surface of the substrate heater 7, and then the inside of the vacuum vessel 1 is exhausted by the vacuum pump 8 through the exhaust pipe 3. 1.33 × 10 ^-4 Exhaust to below Pa. Next, the raw material gas is introduced into the gas mixing box 11 at a predetermined flow rate through the raw material gas introduction pipe 6. The flow rate of the source gas is controlled by a mass flow controller (not shown). As a source gas, a gas containing at least silicon, specifically, a silicon hydride gas such as silane or disilane, a silicon fluoride gas, a halosilane gas such as dichlorosilane or trichlorosilane, and hydrogen are used. Here, the flow rate ratio of hydrogen to the flow rate of the gas containing silicon is set to 5 times or more and 100 times or less. This is because, when the flow rate ratio of hydrogen is less than 5, the amount of hydrogen radicals generated is small, so that the termination of dangling bonds on the surface of the growing film becomes insufficient. Is insufficient, and microcrystalline silicon having good crystallinity is not sufficiently grown. On the other hand, when the flow rate ratio of hydrogen exceeds 100 times, although microcrystalline silicon grows, since the silicon-based radicals involved in film formation are small, the film formation speed becomes extremely low and is thicker than amorphous silicon. This is because, in the case of a microcrystalline silicon-based photovoltaic element requiring a photoelectric conversion layer, productivity is significantly reduced.
[0023]
Next, the pressure inside the vacuum vessel 1 is set to 13.3 Pa or more and 665 Pa or less by a pressure adjusting valve (not shown). If the pressure is less than 13.3 Pa, since the amount of silicon-based radicals involved in film formation is small, the film formation speed is extremely low, and the productivity is significantly reduced. On the other hand, if the pressure exceeds 665 Pa, powder is likely to be generated in the gas phase during film formation. The powder generated during the film formation is taken into the film and extremely deteriorates the film quality of the microcrystalline silicon, and also has an adverse effect such as increasing the frequency of the open maintenance of the vacuum vessel 1.
[0024]
At the same time as the pressure adjustment in the vacuum vessel 1, the substrate heater 7 is energized and heated, and the substrate 9 is heated to 100 ° C. or more and 500 ° C. or less, where an inexpensive material such as glass can be used. If the substrate temperature is lower than 100 ° C., the surface diffusion of silicon-based radicals involved in film formation adsorbed on the surface of the substrate 9 becomes insufficient, so that microcrystalline silicon having good crystallinity does not grow sufficiently.
[0025]
Then, after the substrate temperature and pressure are stabilized, high-frequency power having a frequency of 10 MHz or more and 300 MHz or less is supplied from the high-frequency power supply 4 to the electrode 2 to generate plasma gas and form a microcrystalline silicon film on the surface of the substrate 9. At this time, the impedance matching device 5 is adjusted so that the reflected power is minimized. Here, when the frequency is less than 10 MHz, the plasma density is low and the number of hydrogen radicals excited in the plasma is small, so that the termination of dangling bonds on the surface of the growing film becomes insufficient. This is because there is a problem that the surface diffusion of the silicon-based radicals becomes insufficient and the crystallization of microcrystalline silicon is not promoted. On the other hand, when the frequency exceeds 300 MHz, the voltage distribution in the electrode 2 becomes large, and uniform discharge becomes difficult.
Thereafter, after forming the film for a predetermined time, the raw material gas is exhausted, and the substrate 9 is cooled. Then, the substrate 9 on which the microcrystalline silicon layer is formed is taken out from the vacuum vessel 1.
[0026]
As described above, a microcrystalline silicon layer is formed. At the time of film formation, a gas containing a group III element as a source gas, for example, B ₂ H ₆ , BF ₃ When a gas containing boron such as is added, a p-type microcrystalline silicon layer can be formed. Further, a gas containing a group V element as a source gas, for example, PH ₃ When a gas containing phosphorus is added, an n-type microcrystalline silicon layer can be formed. As described later, when forming the initial layer 13a constituting the microcrystalline p-layer, one or more of the high-frequency power, the substrate temperature, and the pressure of the plasma gas are adjusted, and the transparent electrode is formed. 12 are set so as not to damage them. That is, high-frequency power lower than the high-frequency power when forming the bulk layer 13b constituting the microcrystalline p-layer, or substrate temperature lower than the substrate temperature when forming the bulk layer 13b, or when forming the bulk layer 13b The initial layer 13a is formed at a pressure higher than the pressure of the plasma gas.
[0027]
Next, a method for manufacturing the photovoltaic element 20 shown in FIG. 1 will be described.
First, a PVD method such as a CVD method or a sputtering method is performed on a substrate 9 made of degreased and cleaned glass, for example, tin oxide SnO ₂ A transparent electrode 2 having a thickness of 700 nm is formed by lamination to form a substrate 25. Next, the microcrystalline p-layer initial layer 13a, the microcrystalline p-layer bulk layer 13b, the microcrystalline i-layer 14, and the microcrystalline n-layer 15 are sequentially formed on the substrate 25 by the above-described method. To form
[0028]
Here, the initial layer 13a is formed with a high-frequency power of 25 W and a plasma gas pressure of 66.5 Pa, and has a thickness of 5 nm or more and 50 nm or less, and is 12 nm in the present embodiment. When the film thickness of the initial layer 13a is less than 5 nm, a state where the transparent electrode 12 is partially exposed, that is, a so-called island-like growth occurs. In this case, since a normal semiconductor pn junction is not formed in a portion where the initial layer 13a is not formed, characteristics as a photovoltaic element are significantly reduced. On the other hand, when the film thickness exceeds 50 nm, the amount of light absorbed by the initial layer 13a, which is the light incident side layer, becomes excessive, and the amount of light reaching the microcrystalline i-layer 14, which is the photoelectric conversion layer, is reduced. This is because the conversion efficiency decreases.
[0029]
The bulk layer 13b is formed with a high-frequency power of 75 W, and has a thickness of 5 nm or more and 100 nm or less, and in this embodiment, 30 nm. If the thickness of the bulk layer 13b is less than 5 nm, the thickness as a microcrystalline p-layer is insufficient, and a normal semiconductor pn junction is not formed, so that the characteristics as a photovoltaic element are significantly reduced. On the other hand, when the thickness of the bulk layer 13b exceeds 100 nm, the amount of light absorbed by the bulk layer 13b, which is the light incident side layer, becomes excessive, and the amount of light reaching the microcrystalline i-layer 14, which is the photoelectric conversion layer, decreases. This is because the short-circuit current as a photovoltaic element decreases.
[0030]
The thickness of the microcrystalline i-layer 14 depends on the surface shapes of the transparent electrode 12, the bulk layer 13b, and the microcrystalline i-layer 14, but is not less than 1000 nm and not more than 10,000 nm. This is because if the thickness of the microcrystalline i-layer 14 is less than 1000 nm, incident light cannot be sufficiently absorbed, which causes a problem that a short-circuit current as a photovoltaic element decreases. On the other hand, if the thickness of the microcrystalline i-layer 14 exceeds 10000 nm, the internal electric field generated in the microcrystalline i-layer 14 becomes weak, the open-circuit voltage as a photovoltaic element decreases, and the film-forming time increases, and This is because the property becomes low.
[0031]
The thickness of the microcrystalline n-layer 15 is 5 nm or more and 100 nm or less. When the thickness of the microcrystalline n-layer 15 is less than 5 nm, a state where the microcrystalline i-layer 14 is partially exposed, that is, a so-called island-like growth occurs. In this case, since a normal semiconductor pn junction is not formed in a portion where the microcrystalline n-layer 15 is not formed, characteristics as a photovoltaic element are significantly reduced. On the other hand, if the thickness of the microcrystalline n-layer 15 exceeds 100 nm, the amount of light absorbed by the microcrystalline n-layer 15 becomes excessive, and a problem arises in that the light reflected by the back electrode 16 cannot be used effectively. .
[0032]
Next, on the cell 21 thus formed, the back electrode 16 made of aluminum Al, silver Ag, titanium Ti, nickel Ni, chromium Cr, copper Cu or an alloy thereof is formed by a vacuum evaporation method or a sputtering method. It is formed using a physical vapor deposition method. The back electrode 16 is formed to have a thickness of 200 nm or more so that the light transmitted through the microcrystalline i-layer 14 can be sufficiently reflected. Thus, the photovoltaic element 20 shown in FIG. 1 is completed.
[0033]
Next, as a second embodiment according to the present invention, the film forming conditions of the initial layer 13a are set to a high frequency power of 75 W and a substrate temperature of 150 ° C., respectively, and the other film forming conditions are the same as those of the first embodiment. An electromotive element 20 was formed. Further, as a third embodiment according to the present invention, the film forming conditions of the initial layer 13a are set to a high frequency power of 75 W and a plasma gas pressure of 93.1 Pa, respectively, and the other film forming conditions are the same as those of the first embodiment. Thus, a photovoltaic element 20 was formed. Further, as a first conventional example, a photovoltaic element in which the microcrystalline p-layer 13 is composed only of the bulk layer 13b was formed together with the initial layer 13a having the same film forming conditions as the bulk layer 13b. In the first to third examples and the first conventional example, all the conditions except for the initial layer 13a were formed under the same conditions.
[0034]
Simulated sunlight (AM (passing air amount) 1.5, 100 mW) was applied from the photovoltaic element 20 of the first to third embodiments formed as described above and the glass substrate 9 side of the conventional photovoltaic element. / Cm ² ) And the respective photoelectric conversion efficiencies were measured. Table 1 shows the results.
[0035]
[Table 1]

[0036]
Table 1 shows relative values with the photoelectric conversion efficiency of the photovoltaic element of the first conventional example set to 1.00. In the first to third embodiments, the high frequency power, the substrate temperature and the pressure at the time of forming the initial layer 13a are controlled, and the transparent electrode 12 as the underlayer is formed more gently than the first conventional example. It can be confirmed that the film conditions were set. That is, in the first embodiment, the high-frequency power is smaller than that of the first conventional example, in the second embodiment, the substrate temperature is smaller than that of the first conventional example, and in the third embodiment, the pressure of the plasma gas is As compared with the first conventional example, the generation of damage to the transparent electrode 12 during the formation of the microcrystalline p-layer 13 is suppressed, the deterioration of the semiconductor characteristics of the transparent electrode 12 is suppressed, and the effect of suppressing the damage is suppressed. The occurrence of diffusion and intrusion of elements and the like deposited from the transparent electrode 12 serving as the underlying layer into the microcrystalline p-layer 13 is suppressed, and the occurrence of deterioration in semiconductor characteristics of the microcrystalline p-layer 13 is suppressed. It can be confirmed that it has been improved. In the first to third embodiments, it can be confirmed that the improvement is 11% to 15% as compared with the first conventional example.
[0037]
Next, a plurality of photovoltaic elements 20 were formed by making only the film thickness of the initial layer 13a different from each other, and setting all the film forming conditions except for the other times to be the same as those in the first embodiment. The photoelectric conversion efficiency of each photovoltaic element 20 was measured. That is, FIG. 4 shows the relationship between the thickness of the initial layer 13a and the photoelectric conversion efficiency. FIG. 4 shows relative values with the conversion efficiency of the photovoltaic element of the first conventional example set to 1.00.
[0038]
In FIG. 4, the effect of suppressing the occurrence of damage to the transparent electrode 12 by the initial layer 13 a appears in the range of the thickness of the initial layer 13 a of 5 nm or more and 50 nm or less, and particularly when the thickness of the initial layer 13 a is 15 nm or more and 50 nm or less. It can be confirmed that the effect is remarkable. On the other hand, if the thickness exceeds 50 nm, the effect of suppressing damage to the transparent electrode 12 is saturated, and the amount of light absorbed by the initial layer 13a becomes excessive, the short-circuit current as a photovoltaic element is reduced, and the photoelectric conversion efficiency is reduced. It can be confirmed that it decreases.
[0039]
Next, a fourth embodiment of the present invention will be described. The same parts as those in the above-described first to third embodiments are denoted by the same reference numerals, and description thereof will be omitted.
As shown in FIG. 5, the photovoltaic element 22 according to the fourth embodiment includes a substrate 25, a top cell 23 made of an amorphous silicon element, a bottom cell 24 made of a microcrystalline silicon element, and a back electrode 16. , And these are sequentially laminated. The top cell 23 includes an amorphous p-layer 17 of p-type amorphous silicon, an amorphous i-layer 18 of i-type amorphous silicon, and an amorphous And an n-type layer 19, which is sequentially laminated. The bottom cell 24 includes a microcrystalline p-layer 13, a microcrystalline i-layer 14, and a microcrystalline n-layer 15, which are sequentially stacked. , And a back electrode 16 is provided on the microcrystalline n-layer 15. Here, the microcrystalline p-layer 13 is composed of an initial layer 13a laminated on the surface of the transparent electrode 12 at the initial stage of film formation, and a bulk layer 13b laminated on the surface of the initial layer 13a.
[0040]
Here, the thickness of the amorphous p layer 17 is formed to be 5 nm or more and 50 nm or less. When the thickness of the amorphous p-layer 17 is less than 5 nm, the transparent electrode 12 is partially exposed, that is, so-called island growth. In this case, since a normal semiconductor pn junction is not formed in a portion where the amorphous p layer 17 is not formed, characteristics as a photovoltaic element are significantly reduced. On the other hand, when the thickness of the amorphous p-layer 17 exceeds 50 nm, the amount of light absorbed by the amorphous p-layer 17 which is the light incident layer from the substrate 25 side becomes excessive, and the non-photoelectric conversion layer This is because the amount of light incident on the crystalline i-layer 18 and the microcrystalline i-layer 14 decreases, and the short-circuit current as a photovoltaic element decreases.
[0041]
The film thickness of the amorphous i-layer 18 is 100 nm or more and 500 nm or less. This is because if the thickness of the amorphous i-layer 18 is less than 100 nm, the incident light cannot be sufficiently absorbed, and the short-circuit current as a photovoltaic element decreases. On the other hand, when the film thickness of the amorphous i-layer 18 exceeds 500 nm, the light deterioration becomes large due to the so-called Stepler-Lonski effect in which the defects of the amorphous i-layer 18 increase due to the absorbed light.
[0042]
The thickness of the amorphous n-layer 19 is 5 nm or more and 50 nm or less. When the thickness of the amorphous n-layer 19 is less than 5 nm, the amorphous i-layer 18 is partially exposed, that is, a so-called island growth. In this case, since a normal semiconductor pn junction is not formed in a portion where the amorphous n-layer 19 is not formed, characteristics as a photovoltaic element are significantly reduced. On the other hand, if the film thickness of the amorphous n-layer 19 exceeds 50 nm, the amount of light absorbed by the amorphous n-layer 19 becomes excessive, the amount of light incident on the bottom cell 24 decreases, and short-circuiting as a photovoltaic element occurs. This is because the current decreases.
[0043]
A method for manufacturing the photovoltaic element 22 configured as described above will be described.
First, in the same manner as in the first to third embodiments, a substrate 25 including the glass substrate 9 and the transparent electrode 12 is formed. Next, the top cell 23 is formed on the surface of the substrate 25 on which the transparent electrode 12 is formed. That is, an amorphous p layer 17, an amorphous i layer 18, and an amorphous n layer 19 are sequentially laminated on the transparent electrode 12 by a plasma CVD method. Here, the source gas used for the plasma CVD method is silane SiH ₄ Or disilane Si ₂ H ₆ Or a halosilane-based gas such as dichlorosilane or trichlorosilane, and the power supply frequency at this time is set to 13.56 MPa. When the amorphous p-layer 17 is formed, B containing a group III element as a doping gas is used. ₂ H ₆ , BF ₃ And so on. When the amorphous n-layer 19 is formed, PH containing a group V element is used as a doping gas. ₃ And so on.
[0044]
Next, when the bottom cell 24 is formed on the top cell 23, the initial layer 13a of the microcrystalline p-layer 13 is formed in the same apparatus 30 used in the above-described embodiment by changing the film formation conditions to 30 W of high-frequency power and 30 ° C. of substrate temperature. The temperature was set at 165 ° C. and the pressure of the plasma gas was 66.5 Pa, and the film thickness was 12 nm. Next, the bulk layer 13b of the microcrystalline p-layer 13 was formed to have a thickness of 25 nm by changing the high-frequency power to 75 W among the conditions for forming the initial layer 13a. Thereafter, in the same manner as in the above-described embodiment, the microcrystalline i-layer 14, the microcrystalline n-layer 15, and the back electrode 16 made of aluminum Al are sequentially formed to form the photovoltaic element 22.
[0045]
Next, as a fifth embodiment according to the present invention, of the film forming conditions in the fourth embodiment of the initial layer 13a of the microcrystalline p-layer 13, the substrate temperature was changed to 150 ° C. and the high-frequency power was changed to 75 W, respectively. A photovoltaic element 22 was formed. Further, as the sixth embodiment, the photovoltaic element 22 was formed by changing the plasma gas pressure to 99.8 Pa and the high frequency power to 75 W among the film forming conditions in the fourth embodiment. As a second conventional example, the initial layer 13a of the microcrystalline p-layer 13 is formed under the same film forming conditions as the bulk layer 13b of the microcrystalline p-layer 13 in the fourth to sixth embodiments. A photovoltaic element in which the layer 13 was composed of only the microcrystalline bulk layer 13b was also formed.
[0046]
Simulated sunlight (AM (passing air amount) 1.5, 100 mW) from the photovoltaic element 22 of the fourth to sixth embodiments formed as described above and the glass substrate 9 side of the conventional photovoltaic element. / Cm ² ) And the respective photoelectric conversion efficiencies were measured. Table 2 shows the results.
[0047]
[Table 2]

[0048]
Table 2 shows relative values with the conversion efficiency of the photovoltaic element of the second conventional example set to 1.00. In the fourth to sixth embodiments, the high-frequency power, the substrate temperature and the pressure of the plasma gas at the time of forming the initial layer 13a are controlled, and the amorphous n-layer It can be confirmed that mild film-forming conditions were set for. That is, at the time of forming the initial layer 13a, in the fourth embodiment, the high-frequency power is lower than that of the second conventional example, and in the fifth embodiment, the substrate temperature is lower than that of the second conventional example. In the above, when the pressure of the plasma gas is set higher than in the second conventional example, the occurrence of damage to the amorphous n-layer 19 during the formation of the microcrystalline p-layer 13 is suppressed, and the semiconductor characteristics of the amorphous n-layer 19 deteriorate. The effect of suppressing damage is suppressed, and the effect of diffusion of phosphorus P precipitated from the amorphous n-layer 19 into the microcrystalline p-layer 13 is suppressed, and the semiconductor characteristics of the microcrystalline p-layer 13 are reduced. Since the occurrence of the decrease was suppressed, it can be confirmed that the photoelectric conversion efficiency was improved. That is, it can be confirmed that the fourth to sixth embodiments are improved by 10% to 12% as compared with the second conventional example. This confirms that the photoelectric conversion efficiency is improved by the initial layer 13a of the microcrystalline p-layer 13 even in the tandem structure.
[0049]
As described above, according to the photovoltaic device manufacturing method and the photovoltaic device according to the first to sixth embodiments, when forming the microcrystalline p-layer 13, the bulk layer 13b of microcrystalline silicon is formed. Before, in advance, the initial layer 13a of microcrystalline silicon, at a high frequency power lower than the high frequency power when forming the bulk layer 13b, or at a substrate temperature lower than the substrate temperature when forming the bulk layer 13b, or Since the bulk layer 13b is formed at a pressure higher than the pressure of the plasma gas at the time of formation, the occurrence of damage to the underlying layer, that is, the transparent electrode 12 or the amorphous n-layer 19, when forming the microcrystalline p-layer 13 is suppressed. can do. Thereby, a photovoltaic element having high photoelectric conversion efficiency can be formed.
[0050]
Further, since the thickness of the initial layer 13a is not less than 5 nm and not more than 50 nm, it is possible to suppress the occurrence of damage to the underlying layer, that is, the transparent electrode 12 or the amorphous n-layer 19 when the microcrystalline p-layer 13 is formed, The occurrence of the deterioration of the semiconductor characteristics can be suppressed. Further, the effect of suppressing the occurrence of damage can suppress the diffusion of elements or the like precipitated from the underlayer into the microcrystalline p-layer 13, and can suppress the deterioration of the semiconductor characteristics of the microcrystalline p-layer 13. Furthermore, the amount of light absorption in the initial layer 13a can be optimized, and the occurrence of a decrease in short-circuit current as a photovoltaic element can be efficiently suppressed. As described above, a photovoltaic element having high photoelectric conversion efficiency can be provided.
[0051]
Note that the technical scope of the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.
[0052]
【The invention's effect】
As is clear from the above description, according to the photovoltaic element manufacturing method and the photovoltaic element according to the present invention, when forming the microcrystalline p-layer, the production with a low load on the underlayer is performed in advance. An initial layer of microcrystalline silicon is formed under film conditions, and then a bulk layer of microcrystalline silicon is formed. Therefore, the occurrence of damage to the underlying layer of the microcrystalline p layer is suppressed, and light having good photoelectric conversion characteristics is obtained. An electromotive element can be formed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a photovoltaic element in first to third embodiments according to the present invention.
FIG. 2 is a schematic view showing a manufacturing apparatus used for manufacturing a photovoltaic device according to the present invention.
FIG. 3 is a plan view showing an electrode of the manufacturing apparatus shown in FIG.
FIG. 4 is a diagram showing the relationship between the thickness of an initial layer of a microcrystalline p-layer and the photoelectric conversion efficiency of a photovoltaic element.
FIG. 5 is a cross-sectional view showing a photovoltaic element in fourth to sixth embodiments according to the present invention.
[Explanation of symbols]
1. Vacuum container
2 ... electrode
3. Exhaust pipe
4: High frequency power supply
5 Impedance matching device
6 ... Source gas inlet pipe
7 ... substrate heater
8. Vacuum pump
9 ... Glass substrate
10 ... Coaxial cable
11 ... Gas mixing box
12 ... Transparent electrode
13: Microcrystalline p-layer
13a: Initial layer
13b: Bulk layer
14 ... microcrystalline i-layer
15 ... Microcrystalline n-layer
16 Back electrode
17 ... Amorphous p-layer
18 ... Amorphous i-layer
19 ... Amorphous n-layer
20, 22 ... Photovoltaic element
21 ... cell
23 ... Top cell
24 ... Bottom cell (cell)
25 ... Substrate

Claims (5)

A source gas containing silicon and a hydrogen gas are simultaneously supplied between the substrate and the electrode, and a high frequency wave of 10 MHz or more and 300 MHz or less is applied to generate a plasma gas, and the microcrystalline silicon is formed on the surface of the substrate. A method for manufacturing a photovoltaic device having a cell in which a p-layer, a microcrystalline i-layer, and a microcrystalline n-layer are sequentially stacked,
In forming the microcrystalline p-layer, before forming a microcrystalline silicon bulk layer, an initial layer of microcrystalline silicon is formed in advance with a high-frequency power lower than a high-frequency power used in forming the bulk layer. A method for manufacturing a photovoltaic element, comprising: A source gas containing silicon and a hydrogen gas are simultaneously supplied between the substrate and the electrode, and a high frequency wave of 10 MHz or more and 300 MHz or less is applied to generate a plasma gas, and the microcrystalline silicon is formed on the surface of the substrate. A method for manufacturing a photovoltaic device having a cell in which a p-layer, a microcrystalline i-layer, and a microcrystalline n-layer are sequentially stacked,
In forming the microcrystalline p layer, before forming a bulk layer of microcrystalline silicon, an initial layer of microcrystalline silicon is formed at a substrate temperature lower than the substrate temperature at which the bulk layer is formed. A method for manufacturing a photovoltaic element, comprising: A source gas containing silicon and a hydrogen gas are simultaneously supplied between the substrate and the electrode, and a high frequency wave of 10 MHz or more and 300 MHz or less is applied to generate a plasma gas, and the microcrystalline silicon is formed on the surface of the substrate. A method for manufacturing a photovoltaic device having a cell in which a p-layer, a microcrystalline i-layer, and a microcrystalline n-layer are sequentially stacked,
In forming the microcrystalline p-layer, before forming the bulk layer of microcrystalline silicon, an initial layer of microcrystalline silicon is formed at a higher pressure than the pressure of the plasma gas when forming the bulk layer in advance. A method for manufacturing a photovoltaic element. The method for manufacturing a photovoltaic element according to claim 1,
A method for manufacturing a photovoltaic device, wherein the thickness of the initial layer is 5 nm or more and 50 nm or less. A photovoltaic device manufactured by the method for manufacturing a photovoltaic device according to claim 1.

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