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JP2013008750A - Thin film silicon based solar cell - Google Patents

Thin film silicon based solar cell Download PDF

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JP2013008750A
JP2013008750A JP2011138836A JP2011138836A JP2013008750A JP 2013008750 A JP2013008750 A JP 2013008750A JP 2011138836 A JP2011138836 A JP 2011138836A JP 2011138836 A JP2011138836 A JP 2011138836A JP 2013008750 A JP2013008750 A JP 2013008750A
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amorphous silicon
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Hiroyuki Sonobe
裕之 園部
Toshiaki Sasaki
敏明 佐々木
Keisuke Matsumoto
圭祐 松本
Takahiro Matsuda
高洋 松田
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Kaneka Corp
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Abstract

【課題】а−Ｓｉセルをその構成要素に持つ薄膜Ｓｉ系太陽電池の発電効率改善には、а−Ｓｉセルの短波長の光による発電電流を改善する。また、а−Ｓｉセルの光劣化を抑制する、即ち保持率を改善する。
【解決手段】ｐｉｎ接合を１以上含む薄膜シリコン系太陽電池であって、最も光入射側に位置するｐｉｎ接合のｉ層はアモルファスシリコンからなりｐ層は計測波長１０００ｎｍにおける屈折率Ｎｄが２．５以上２．９以下であり且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下であり、当該ｐ層とｉ層とにそれぞれ接する界面層が、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層である。
【選択図】図１To improve the power generation efficiency of a thin-film Si-based solar cell having an а-Si cell as a constituent element, the power generation current due to light having a short wavelength of the а-Si cell is improved. Further, the light deterioration of the а-Si cell is suppressed, that is, the retention rate is improved.
A thin film silicon solar cell including one or more pin junctions, wherein the i layer of the pin junction located closest to the light incident side is made of amorphous silicon, and the p layer has a refractive index Nd of 2.5 at a measurement wavelength of 1000 nm. 2.9 or less and the bright conductivity is greater than 1 × 10 −9 S / cm and less than or equal to 1 × 10 −6 S / cm, and the interface layers in contact with the p layer and the i layer are light incident A layer having a two-layer structure composed of an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer in this order from the side.
[Selection] Figure 1

Description

本発明は、薄膜シリコン系太陽電池の作製方法に関するものである。   The present invention relates to a method for manufacturing a thin film silicon solar cell.

以下において、シリコンを単にＳｉと略して表記することが有る。地球温暖化防止の観点から、発電時に二酸化炭素を排出しない太陽光発電への期待が高まっている。単結晶Ｓｉや多結晶Ｓｉを用いた結晶系Ｓｉ太陽電池や、カドミウムテルル（ＣｄＴｅ）等の化合物半導体を用いた太陽電池は発電効率も高く、現在主流の太陽電池となっている。   In the following, silicon may be simply abbreviated as Si. From the viewpoint of preventing global warming, there is an increasing expectation for solar power generation that does not emit carbon dioxide during power generation. Crystalline Si solar cells using single crystal Si or polycrystalline Si, and solar cells using compound semiconductors such as cadmium tellurium (CdTe) have high power generation efficiency and are currently mainstream solar cells.

一方、アモルファスシリコン（а−Ｓｉとも表記する）や微結晶シリコン（μｃ−Ｓｉとも表記する）等を用いた薄膜Ｓｉ系太陽電池は、大面積化が容易なプロセスを用いて製造出来ることから、コストダウンに優れた太陽電池である。しかしながら、前記太陽電池と比べて発電効率の低いことが問題となっている。特に、薄膜а−Ｓｉを発電層（ｉ層）としてその構成要素に含む太陽電池では光照射によって発電効率が低下する問題すなわち光劣化という課題を抱えている。   On the other hand, thin-film Si solar cells using amorphous silicon (also expressed as а-Si), microcrystalline silicon (also expressed as μc-Si), and the like can be manufactured using a process that can easily increase the area, It is a solar cell excellent in cost reduction. However, there is a problem that the power generation efficiency is lower than that of the solar cell. In particular, a solar cell including a thin film а-Si as a power generation layer (i layer) as a constituent element has a problem that power generation efficiency is reduced by light irradiation, that is, a problem of light deterioration.

光劣化はа−Ｓｉ発電層（а−ｉ層）に起因する現象だが、а−ｉ層とドーピング層（ｐ層、ｎ層）とのバンドギャップ整合性等の界面特性も大きく影響している。例えば特許文献１では、ｐ層／ｉ層界面及びｉ層／ｎ層界面に界面層を挿入することで、各界面でのバンドギャップ不整合を抑制する手法が述べられている。   Photodegradation is a phenomenon caused by the а-Si power generation layer (а-i layer), but interface characteristics such as band gap matching between the а-i layer and the doping layer (p layer, n layer) are also greatly affected. . For example, Patent Document 1 describes a technique of suppressing band gap mismatch at each interface by inserting interface layers at the p layer / i layer interface and the i layer / n layer interface.

また、ｉ層／ｎ層界面よりもｐ層／ｉ層界面の方が太陽電池の発電効率に与える影響が大きいことから、特許文献２ではｐ層／ｉ層界面の界面層を２層構造とし、このうち前記界面層のｐ層側は僅かにドーパント（ボロン（Ｂ））を添加し、前記界面層のｉ層側はさらに僅かなＢの添加或いは添加なしとすることで発電効率が改善するとしている。   In addition, since the p layer / i layer interface has a greater influence on the power generation efficiency of the solar cell than the i layer / n layer interface, in Patent Document 2, the interface layer at the p layer / i layer interface has a two-layer structure. Of these, the p-layer side of the interface layer is slightly added with a dopant (boron (B)), and the i-layer side of the interface layer is further added or no addition of B improves power generation efficiency. It is said.

特開２００４−３３５８２３号公報JP 2004-335823 A 特開２００３−８０３８号公報JP 2003-8038 A

また、薄膜Ｓｉ系太陽電池の発電効率改善方法として、а−Ｓｉセルを最も光入射側のトップセルとして用い、а−Ｓｉよりもバンドギャップの小さいμｃ−Ｓｉ等をボトムセルとして用いるタンデム型或いはトリプル型太陽電池も提案されている。а−Ｓｉセル単体では太陽光のうち、およそ波長３００ｎｍ〜８００ｎｍの光しか発電に寄与していない。一方、前記タンデム型或いはトリプル型太陽電池は、а−Ｓｉセル単体では発電に寄与させることが出来なかった波長８００ｎｍ以上の光も発電に利用することで発電効率を改善させている。   Moreover, as a method for improving the power generation efficiency of a thin-film Si-based solar cell, a tandem type or triple using an а-Si cell as a top cell on the light incident side and using a μc-Si or the like having a band gap smaller than that of а-Si as a bottom cell. Type solar cells have also been proposed. In the single а-Si cell, only light having a wavelength of about 300 nm to 800 nm contributes to power generation in sunlight. On the other hand, the tandem-type or triple-type solar cell improves power generation efficiency by using light having a wavelength of 800 nm or more, which cannot be contributed to power generation with a single а-Si cell, for power generation.

これらタンデム型或いはトリプル型太陽電池の場合、高効率化のために各構成セルの発電電流を大きくすることが求められている。а−Ｓｉセルは最も光入射側に位置しているため、特に短波長（３００ｎｍ〜５００ｎｍ）の光を発電に寄与させることが望ましい。波長５００ｎｍ以上の光はミドルセル或いはボトムセルの発電にも寄与するため、а−Ｓｉセルで波長５００ｎｍ以上の光を吸収してしまった場合、それだけミドルセル或いはボトムセルの発電電流が低下することになり、別の手段でミドルセル或いはボトムセルの発電電流を向上させる必要が生じる。しかしながら、波長３００ｎｍ〜５００ｎｍの光はа−Ｓｉセルのみで使用されるため、他のミドルセル或いはボトムセルに影響を与えることなく、а−Ｓｉセルの発電電流を向上させることが出来る。   In the case of these tandem type or triple type solar cells, it is required to increase the power generation current of each constituent cell for high efficiency. Since the а-Si cell is located closest to the light incident side, it is desirable to make light of a short wavelength (300 nm to 500 nm) contribute to power generation. Since light with a wavelength of 500 nm or more also contributes to power generation in the middle cell or bottom cell, if light with a wavelength of 500 nm or more is absorbed in the а-Si cell, the power generation current of the middle cell or bottom cell is reduced accordingly. Thus, it is necessary to improve the generated current of the middle cell or the bottom cell. However, since light having a wavelength of 300 nm to 500 nm is used only in the а-Si cell, the power generation current of the а-Si cell can be improved without affecting other middle cells or bottom cells.

а−Ｓｉセルをその構成要素に持つ薄膜Ｓｉ系太陽電池の発電効率改善には、а−Ｓｉセルの発電電流向上が重要であり、本発明は特に短波長（３００ｎｍ〜５００ｎｍ）の光による発電電流を改善させることを目的とする。同時に、この改善によってа−Ｓｉセルの光劣化を抑制する、即ち保持率（「光劣化後発電効率」／「初期発電効率」（％））を改善することを目的とする。   In order to improve the power generation efficiency of a thin-film Si solar cell having an а-Si cell as its constituent element, it is important to improve the power generation current of the а-Si cell, and the present invention particularly generates power using light of a short wavelength (300 nm to 500 nm). The purpose is to improve the current. At the same time, this improvement aims to suppress the light deterioration of the а-Si cell, that is, to improve the retention rate ("power generation efficiency after light deterioration" / "initial power generation efficiency" (%)).

本発明の第１は、ｐｉｎ接合を１以上含む薄膜シリコン系太陽電池であって、最も光入射側に位置するｐｉｎ接合のｉ層はアモルファスシリコンからなりｐ層は計測波長１０００ｎｍにおける屈折率Ｎｄが２．５以上２．９以下であり且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下であり、当該ｐ層とｉ層とにそれぞれ接する界面層が、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層であることを特徴とする、薄膜シリコン系太陽電池、である。 The first of the present invention is a thin-film silicon solar cell including one or more pin junctions, wherein the i layer of the pin junction located closest to the light incident side is made of amorphous silicon, and the p layer has a refractive index Nd at a measurement wavelength of 1000 nm. The interface layer is 2.5 or more and 2.9 or less and the bright conductivity is greater than 1 × 10 −9 S / cm and less than or equal to 1 × 10 −6 S / cm, and the p-layer and the i-layer are in contact with each other. A thin-film silicon solar cell, which is a layer having a two-layer structure including an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer in order from the light incident side.

特許文献２ではｐ層／ｉ層界面の界面層を２層構造とし、このうち前記界面層のｐ層側は僅かにドーパント（ボロン（Ｂ））を添加し、前記界面層のｉ層側はさらに僅かなＢの添加或いは添加なしとすることで発電効率が改善するとしている。これに対して本発明では、ｐ層／ｉ層界面の界面層を２層構造とする点では共通するが、この界面層のｐ層側すなわち光入射側は真性のアモルファス炭化ケイ素層であり、この界面層のｉ層側すなわち光入射側から遠い側は真性のアモルファスシリコン層で有る点で、特許文献２とは異なる。   In Patent Document 2, the interface layer at the interface between the p layer and the i layer has a two-layer structure, of which the p layer side of the interface layer is slightly added with dopant (boron (B)), and the i layer side of the interface layer is Furthermore, it is said that power generation efficiency is improved by adding or not adding a little B. In contrast, the present invention is common in that the interface layer at the interface between the p layer and the i layer has a two-layer structure, but the p layer side of the interface layer, that is, the light incident side is an intrinsic amorphous silicon carbide layer, This interface layer is different from Patent Document 2 in that the i layer side, that is, the side far from the light incident side is an intrinsic amorphous silicon layer.

すなわち、ｐ層／ｉ層界面の界面層が、特許文献２ではわずかにボロンを添加しているためｐ型の性質を有するのに対して、本発明では真性である点が異なる。本発明では、ｐ層／ｉ層界面の界面層を真性である２層構造、すなわち、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層とすることによって、ボロン添加による膜中欠陥を抑制しながらｐ層／ｉ層間のバンドギャップを緩やかに繋ぐという顕著な効果を有する。このとき、上記２層目の真性アモルファスシリコン層は、それ単体で製膜した場合（単膜）では微結晶だがセル構造で用いた場合にはアモルファスという界面層а−ｉ層条件を採用した。通常、バンドギャップ整合性の観点や、界面層を製膜したときの下地層（ｐ層）へのダメージの観点から、当業者は界面層の製膜条件は単膜において微結晶となる条件を検討しないものであった。しかしながら、本発明においては、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層（単膜では微結晶となる条件）とからなる２層構造の層を採用することによって、当業者が容易に予想できないｐ層／ｉ層間のバンドギャップ整合性という効果を発現する。また、筆者らはバンドギャップを検討する際に、代わりの物性として屈折率（計測波長１０００ｎｍ)を指標とした。バンドギャップは通常タウツプロットから算出するが、この算出値は誤差が大きくバンドギャップ整合性を検討する際に不適当であったためである。   That is, the interface layer at the interface between the p layer and the i layer has p-type properties because a slight amount of boron is added in Patent Document 2, but differs in that it is intrinsic in the present invention. In the present invention, the interface layer at the p layer / i layer interface is an intrinsic two-layer structure, that is, a layer having a two-layer structure comprising an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer in order from the light incident side. This has a remarkable effect of gently connecting the band gap between the p layer and the i layer while suppressing defects in the film due to boron addition. At this time, the second intrinsic amorphous silicon layer employed was an interface layer i-i layer condition in which it was microcrystalline when formed alone (single film) but amorphous when used in a cell structure. Usually, from the viewpoint of band gap matching and the viewpoint of damage to the underlying layer (p layer) when the interface layer is formed, those skilled in the art have determined that the film forming conditions for the interface layer are the conditions for forming a microcrystal in a single film. It was not considered. However, in the present invention, a person skilled in the art adopts a layer having a two-layer structure including an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer (conditions for forming a microcrystal in a single film) in order from the light incident side. However, the effect of the band gap matching between the p layer / i layer, which cannot be easily predicted, is exhibited. Further, the authors used the refractive index (measurement wavelength 1000 nm) as an index as an alternative physical property when examining the band gap. This is because the band gap is usually calculated from the Tautz plot, but this calculated value is large in error and is inappropriate when considering the band gap matching.

本発明の第２は、前記真性のアモルファス炭化ケイ素層は計測波長１０００ｎｍにおける屈折率Ｎｐｉが３．２以上３．４以下である、前記の薄膜シリコン系太陽電池、である。   The second aspect of the present invention is the above-described thin-film silicon solar cell, wherein the intrinsic amorphous silicon carbide layer has a refractive index Npi of 3.2 or more and 3.4 or less at a measurement wavelength of 1000 nm.

Ｎｐｉが３．２以上３．４以下である事によって、ｐ層と前記真性のアモルファスシリコン層間のバンドギャップ整合性が良いという効果を有する点で好ましい。   Npi of 3.2 or more and 3.4 or less is preferable in that the band gap matching between the p layer and the intrinsic amorphous silicon layer is good.

本発明の第３は、前記真性のアモルファスシリコン層はそれ単体でガラス基板上に膜厚３０ｎｍの膜を製膜した場合には微結晶シリコンであり、且つその微結晶シリコンの計測波長１０００ｎｍにおける屈折率Ｎｉｂが３．１以上３．３以下である、前記の薄膜シリコン系太陽電池、である。   According to a third aspect of the present invention, the intrinsic amorphous silicon layer alone is microcrystalline silicon when a film having a thickness of 30 nm is formed on a glass substrate, and the refraction of the microcrystalline silicon at a measurement wavelength of 1000 nm is achieved. The thin film silicon-based solar cell described above, wherein the rate Nib is 3.1 or more and 3.3 or less.

Ｎｉｂが３．１以上３．３以下である事によって、前記真性のアモルファス炭化ケイ素層とｉ層間のバンドギャップ整合性が良いという効果を有する点で好ましい。   When Nib is 3.1 or more and 3.3 or less, it is preferable in that it has an effect of good band gap matching between the intrinsic amorphous silicon carbide layer and the i layer.

屈折率が、Ｎｄ（２．５〜２．９）／Ｎｐｉ（３．２〜３．４）／Ｎｉｂ（３．１〜３．３）という順番であることによって、ｐ層／前記真性のアモルファス炭化ケイ素層／前記真性のアモルファスシリコン層／ｉ層（計測波長１０００ｎｍにおける屈折率３．５〜３．７）の４層間のバンドギャップ整合性が良いという点で、好ましい。   When the refractive index is in the order of Nd (2.5 to 2.9) / Npi (3.2 to 3.4) / Nib (3.1 to 3.3), the p layer / the intrinsic amorphous It is preferable in terms of good band gap matching between the four layers of silicon carbide layer / intrinsic amorphous silicon layer / i layer (refractive index of 3.5 to 3.7 at a measurement wavelength of 1000 nm).

すなわち本発明の太陽電池は、ｐｉｎ接合を少なくとも１つは有する薄膜Ｓｉ系太陽電池において、最も光入射側に位置するｐｉｎ接合の光入射側のドーピング層（ｐ層）の屈折率Ｎｄ（計測波長：１０００ｎｍ）が２．５以上２．９以下で且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下とし、さらに当該ｐ層と光電変換層（ｉ層）との界面層（ｐ／ｉ界面層）を、ドーピングしない（ノンドープ）アモルファス炭化ケイ素（а−ＳｉＣ）と、アモルファスｉ層（ａ−ｉ層）との２層構造としたことを特徴とする薄膜Ｓｉ系太陽電池である。 That is, the solar cell of the present invention is a thin film Si solar cell having at least one pin junction, and the refractive index Nd (measurement wavelength) of the doping layer (p layer) on the light incident side of the pin junction located closest to the light incident side. : 1000 nm) is 2.5 or more and 2.9 or less and the bright conductivity is greater than 1 × 10 −9 S / cm and 1 × 10 −6 S / cm or less, and the p layer and the photoelectric conversion layer (i layer) ) Interface layer (p / i interface layer) has a two-layer structure of non-doped (non-doped) amorphous silicon carbide (а-SiC) and amorphous i layer (ai layer). It is a thin film Si solar cell.

また、本発明の太陽電池は、ｐｉｎ接合を少なくとも１つは有する薄膜Ｓｉ系太陽電池において、最も光入射側に位置するｐｉｎ接合の光入射側のｐ層のＮｄが２．５以上２．９以下で且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下とし、さらに当該ｐ層とｉ層とのｐ／ｉ界面層を、ノンドープа−ＳｉＣと、ａ−ｉ層との２層構造とし、且つ前記а−ＳｉＣの屈折率Ｎｐｉ（計測波長：１０００ｎｍ）を３．２以上３．４以下としたことを特徴とする薄膜Ｓｉ系太陽電池、である。 The solar cell of the present invention is a thin-film Si solar cell having at least one pin junction, and the Nd of the p layer on the light incident side of the pin junction located closest to the light incident side is 2.5 or more and 2.9. And having a bright conductivity of greater than 1 × 10 −9 S / cm and 1 × 10 −6 S / cm or less, and a p / i interface layer between the p layer and the i layer, A thin-film Si-based solar cell having a two-layer structure with an ai layer and having a refractive index Npi (measurement wavelength: 1000 nm) of the a-SiC of 3.2 or more and 3.4 or less. .

また、本発明の太陽電池は、ｐｉｎ接合を少なくとも１つは有する薄膜Ｓｉ系太陽電池において、最も光入射側に位置するｐｉｎ接合の光入射側のｐ層のＮｄが２．５以上２．９以下で且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下とし、さらに当該ｐ層とｉ層とのｐ／ｉ界面層を、ノンドープа−ＳｉＣと、ａ−ｉ層との２層構造とし、且つ前記ａ−ｉ層はそれ単体でガラス基板上に膜厚３０ｎｍの膜を製膜した場合には微結晶シリコンであり、且つその微結晶シリコンの屈折率Ｎｉｂ（計測波長：１０００ｎｍ）を３．１以上３．３以下としたことを特徴とする薄膜Ｓｉ系太陽電池、である。 The solar cell of the present invention is a thin-film Si solar cell having at least one pin junction, and the Nd of the p layer on the light incident side of the pin junction located closest to the light incident side is 2.5 or more and 2.9. And having a bright conductivity of greater than 1 × 10 −9 S / cm and 1 × 10 −6 S / cm or less, and a p / i interface layer between the p layer and the i layer, The ai layer is microcrystalline silicon when a single layer of the ai layer is formed on a glass substrate, and the refraction of the microcrystalline silicon. A thin-film Si-based solar cell having a rate Nib (measurement wavelength: 1000 nm) of 3.1 or more and 3.3 or less.

また本発明の太陽電池は、ｐｉｎ接合を少なくとも１つは有する薄膜Ｓｉ系太陽電池において、最も光入射側に位置するｐｉｎ接合の光入射側のｐ層のＮｄが２．５以上２．９以下で且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下とし、さらに当該ｐ層とｉ層とのｐ／ｉ界面層を、ノンドープа−ＳｉＣと、ａ−ｉ層との２層構造とし、且つ前記а−ＳｉＣのＮｐｉを３．２以上３．４以下とし、且つ前記ａ−ｉ層はそれ単体でガラス基板上に膜厚３０ｎｍの膜を製膜した場合には微結晶シリコンであり、且つその微結晶シリコンの屈折率Ｎｉｂを３．１以上３．３以下としたことを特徴とする薄膜Ｓｉ系太陽電池、である。 The solar cell of the present invention is a thin-film Si solar cell having at least one pin junction, and the Nd of the p-layer on the light incident side of the pin junction located closest to the light incident side is 2.5 or more and 2.9 or less. And the bright conductivity is greater than 1 × 10 −9 S / cm and less than or equal to 1 × 10 −6 S / cm, and the p / i interface layer between the p layer and the i layer is formed of non-doped SiC and a A two-layer structure with -i layer, Npi of the а-SiC is set to 3.2 or more and 3.4 or less, and the ai layer is formed as a single film with a film thickness of 30 nm on a glass substrate. In this case, the thin-film Si-based solar cell is characterized by being microcrystalline silicon and having a refractive index Nib of 3.1 to 3.3 in the microcrystalline silicon.

本発明により、ｐｉｎ接合を少なくとも１つは有する薄膜Ｓｉ系太陽電池において、最も光入射側に位置するｐｉｎ接合（а−Ｓｉセル）の短波長域の光感度（短波長感度）が改善され、а−Ｓｉセルの短絡電流密度（Ｊｓｃ）が向上する。また、保持率も改善される。ｐ層／ｉ層の界面層を、これまで２層構造のｐ型の層で形成してきた先行技術から、セルの直列抵抗が増加することや微結晶の製膜条件によって下地となるｐ層にダメージが生じるなどの阻害要因が有る関係で当業者は検討もしなかった２層構造のｉ型の層に代えることによって、これまで当業者が予想も出来ないほどの顕著なバンドギャップ整合性という効果が発現した。   According to the present invention, in a thin-film Si solar cell having at least one pin junction, the light sensitivity in the short wavelength region (short wavelength sensitivity) of the pin junction (а-Si cell) located closest to the light incident side is improved. The short circuit current density (Jsc) of the а-Si cell is improved. Also, the retention rate is improved. From the prior art in which the p-layer / i-layer interface layer has been formed with a p-type layer having a two-layer structure, the p-layer serving as a base layer is increased depending on the increase in series resistance of the cell and the microcrystalline film-forming conditions. By replacing the i-type layer with a two-layer structure, which has not been studied by those skilled in the art due to the obstruction factors such as the occurrence of damage, the effect of remarkable bandgap matching that could not be predicted by those skilled in the art until now Expressed.

本発明における薄膜а−Ｓｉ太陽電池のセル構造Cell structure of thin-film solar cell in the present invention

本発明の第１は、ｐｉｎ接合を１以上含む薄膜シリコン系太陽電池であって、最も光入射側に位置するｐｉｎ接合のｉ層はアモルファスシリコンからなりｐ層は計測波長１０００ｎｍにおける屈折率Ｎｄが２．５以上２．９以下であり且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下であり、当該ｐ層とｉ層とにそれぞれ接する界面層が、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層であることを特徴とする、薄膜シリコン系太陽電池、である。 The first of the present invention is a thin-film silicon solar cell including one or more pin junctions, wherein the i layer of the pin junction located closest to the light incident side is made of amorphous silicon, and the p layer has a refractive index Nd at a measurement wavelength of 1000 nm. The interface layer is 2.5 or more and 2.9 or less and the bright conductivity is greater than 1 × 10 −9 S / cm and less than or equal to 1 × 10 −6 S / cm, and the p-layer and the i-layer are in contact with each other. A thin-film silicon solar cell, which is a layer having a two-layer structure including an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer in order from the light incident side.

ｐｉｎ接合を１以上含む薄膜シリコン系太陽電池とは、ｐ型半導体層、実質的に真性なｉ型半導体層、ｎ型半導体層を積層したｐｉｎ接合を少なくとも１つ有し、且つ各層の構成成分にシリコンを含むことを特徴とした太陽電池を指す。   A thin-film silicon-based solar cell including one or more pin junctions includes at least one pin junction in which a p-type semiconductor layer, a substantially intrinsic i-type semiconductor layer, and an n-type semiconductor layer are stacked, and the constituent components of each layer Refers to a solar cell characterized by containing silicon.

最も光入射側に位置するｐｉｎ接合のｉ層はアモルファスシリコンからなるとは、ｉ層単膜をラマン分光法により評価した場合に結晶ピーク（５２０ｃｍ−１のピーク）が観察されないｉ層のことを指す。 The pin junction i layer located closest to the light incident side is made of amorphous silicon, which means an i layer in which no crystal peak (520 cm −1 peak) is observed when an i layer single film is evaluated by Raman spectroscopy. .

アモルファスシリコンは、例えばプラズマ化学気相成長（プラズマＣＶＤ）法を用いて原料ガスをシラン（ＳｉＨ４）と水素（Ｈ２）とし、Ｈ２／ＳｉＨ４ガス混合比を０〜５０、圧力（Ｐａ）を１０〜７００Ｐａ、パワー密度（ｍＷ／ｃｍ２）を５〜５０ｍＷ／ｃｍ２とした製膜条件で製造される。 Amorphous silicon uses, for example, a plasma chemical vapor deposition (plasma CVD) method, the source gas is silane (SiH 4 ) and hydrogen (H 2 ), the H 2 / SiH 4 gas mixture ratio is 0 to 50, and the pressure (Pa ) the 10～700Pa, is produced power density (mW / cm 2) with deposition conditions were as 5~50mW / cm 2.

最も光入射側に位置するｐｉｎ接合のｐ層が計測波長１０００ｎｍにおける屈折率Ｎｄが２．５以上２．９以下であり且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下であるとは、単膜（膜厚３０ｎｍ）をガラス基板（日本電気硝子製ＯＡ−１０基板）上に作製し、評価した結果の値である。屈折率は分光エリプソを用いて評価し、フィッティングモデルはＯＡ−１０／評価膜(Ｔａｕｃ−Ｌｏｒｅｎｔｚ ｍｏｄｅｌ)／表面酸化膜とした。導電率は、単膜上にコプラナー型電極を作製し評価した。 The p-layer of the pin junction located closest to the light incident side has a refractive index Nd of 2.5 or more and 2.9 or less at a measurement wavelength of 1000 nm and a bright conductivity greater than 1 × 10 −9 S / cm to 1 × 10 − That it is 6 S / cm or less is the value of the result of producing and evaluating a single film (film thickness 30 nm) on a glass substrate (OA-10 substrate manufactured by Nippon Electric Glass). The refractive index was evaluated using a spectroscopic ellipso, and the fitting model was OA-10 / evaluation film (Tauc-Lorentz model) / surface oxide film. The electrical conductivity was evaluated by preparing a coplanar electrode on a single film.

上記のＮｄ及び明導電率の範囲とすることにより、セルへの光取り込み量を増大させつつ、セルの直列抵抗成分の増加を抑えることが出来る。一般的な作り方は、例えばプラズマＣＶＤ法を用いて原料ガスをシラン（ＳｉＨ４）、水素（Ｈ２）、メタン（ＣＨ４）、ジボラン（Ｂ２Ｈ６）とし、ＣＨ４／ＳｉＨ４ガス混合比を１〜１０、（Ｈ２＋Ｂ２Ｈ６）／ＳｉＨ４ガス混合比を５〜１５０、シランに対するジボラン濃度（Ｂ２Ｈ６／ＳｉＨ４）（％）を０．５％〜７％、圧力（Ｐａ）を１０〜７００Ｐａ、パワー密度（ｍＷ／ｃｍ２）を５〜２５０ｍＷ／ｃｍ２とすることである。 By setting the above range of Nd and bright conductivity, it is possible to suppress an increase in the series resistance component of the cell while increasing the amount of light taken into the cell. A common method is to use, for example, a plasma CVD method, using silane (SiH 4 ), hydrogen (H 2 ), methane (CH 4 ), diborane (B 2 H 6 ) as a source gas, and a CH 4 / SiH 4 gas mixture. The ratio is 1 to 10, the (H 2 + B 2 H 6 ) / SiH 4 gas mixture ratio is 5 to 150, the diborane concentration (B 2 H 6 / SiH 4) (%) to silane is 0.5% to 7%, and the pressure the (Pa) 10~700Pa, is that the power density (mW / cm 2) and 5~250mW / cm 2.

当該ｐ層とｉ層とにそれぞれ接する界面層が、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層であることを特徴とする、薄膜シリコン系太陽電池について、説明する。   A thin-film silicon-based system, wherein the interface layer in contact with each of the p layer and the i layer is a layer having a two-layer structure including an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer in order from the light incident side. The solar cell will be described.

アモルファス炭化ケイ素層の一般的な作り方は、例えばプラズマＣＶＤ法を用いて原料ガスをシラン（ＳｉＨ４）、水素（Ｈ２）、メタン（ＣＨ４）とし、ＣＨ４／ＳｉＨ４ガス混合比を０．１〜５、圧力（Ｐａ）を１０〜７００Ｐａ、パワー密度（ｍＷ／ｃｍ２）を５〜２５０ｍＷ／ｃｍ２とすることである。 A general method for forming an amorphous silicon carbide layer is, for example, using a plasma CVD method, using silane (SiH 4 ), hydrogen (H 2 ), methane (CH 4 ) as a raw material gas, and a CH 4 / SiH 4 gas mixture ratio of 0. .1～5 is to pressure (Pa) 10~700Pa, the power density (mW / cm 2) and 5~250mW / cm 2.

アモルファスシリコン層の一般的な作り方は、例えばプラズマＣＶＤ法を用いて原料ガスをシラン（ＳｉＨ４）と水素（Ｈ２）とし、Ｈ２／ＳｉＨ４ガス混合比を５０〜１５０、圧力（Ｐａ）を１００〜１４００Ｐａ、パワー密度（ｍＷ／ｃｍ２）を２０〜１００ｍＷ／ｃｍ２とした製膜条件で製造される。 A general method for making an amorphous silicon layer is, for example, by using a plasma CVD method, the source gas is silane (SiH 4 ) and hydrogen (H 2 ), the H 2 / SiH 4 gas mixture ratio is 50 to 150, and the pressure (Pa). the 100～1400Pa, is produced power density (mW / cm 2) with deposition conditions were a 20 to 100 mW / cm 2.

このとき、上記界面層の真性アモルファスシリコン層は、単膜では微結晶シリコンだがセル構造で用いた場合にはアモルファスシリコンという点が光電変換層のアモルファスシリコンとは異なる。ここで言う微結晶シリコンとは、ラマン分光法により膜を評価した場合に結晶ピーク（５２０ｃｍ−１のピーク）が観察されることを指す。微結晶シリコンはそのバンドギャップがアモルファスシリコンより小さいため、通常、バンドギャップ整合性の観点からｐ層とｉ層の間には挿入しない。また、微結晶シリコンのプラズマＣＶＤ法における製膜条件は、一般にＨ２／ＳｉＨ４ガス混合比が高く、また印加電力（パワー密度）も大きいために、微結晶シリコンを製膜したときの下地層（ｐ層）へのダメージが大きい。この観点から、当業者は界面層の製膜条件は単膜において微結晶シリコンとなる条件を検討しないものであった。しかしながら、本発明においては、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層（単膜では微結晶シリコンとなる条件）とからなる２層構造の層を採用することによって、当業者が容易に予想できないｐ層／ｉ層間のバンドギャップ整合性という効果を発現する。 At this time, the intrinsic amorphous silicon layer of the interface layer is different from the amorphous silicon of the photoelectric conversion layer in that it is microcrystalline silicon in a single film but is amorphous silicon when used in a cell structure. The microcrystalline silicon referred to here means that a crystal peak (520 cm −1 peak) is observed when the film is evaluated by Raman spectroscopy. Since the band gap of microcrystalline silicon is smaller than that of amorphous silicon, it is usually not inserted between the p layer and the i layer from the viewpoint of band gap matching. The film formation conditions in the plasma CVD method of microcrystalline silicon generally have a high H 2 / SiH 4 gas mixture ratio and a large applied power (power density), so that the underlying layer is formed when microcrystalline silicon is formed. The damage to (p layer) is large. From this point of view, those skilled in the art have not considered the conditions for forming the interface layer as microcrystalline silicon in a single film. However, in the present invention, by adopting a layer having a two-layer structure including an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer (conditions for forming a microcrystalline silicon in a single film) in order from the light incident side, The effect of the band gap matching between the p layer / i layer that cannot be easily predicted by a trader is exhibited.

本発明の第１は、ｐｉｎ接合を１以上含む薄膜シリコン系太陽電池であって、最も光入射側に位置するｐｉｎ接合のｉ層はアモルファスシリコンからなりｐ層は計測波長１０００ｎｍにおける屈折率Ｎｄが２．５以上２．９以下であり且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下であり、当該ｐ層とｉ層とにそれぞれ接する界面層が、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層であることを特徴とする、薄膜シリコン系太陽電池、である。 The first of the present invention is a thin-film silicon solar cell including one or more pin junctions, wherein the i layer of the pin junction located closest to the light incident side is made of amorphous silicon, and the p layer has a refractive index Nd at a measurement wavelength of 1000 nm. The interface layer is 2.5 or more and 2.9 or less and the bright conductivity is greater than 1 × 10 −9 S / cm and less than or equal to 1 × 10 −6 S / cm, and the p-layer and the i-layer are in contact with each other. A thin-film silicon solar cell, which is a layer having a two-layer structure including an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer in order from the light incident side.

なお、本発明では、Ｎｄが２．５以上２．９以下であり且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下である事によって、セルへの光取り込み量を増大させつつ、セルの直列抵抗成分の増大を抑えるという効果を有する点で好ましい。 In the present invention, Nd is not less than 2.5 and not more than 2.9, and the bright conductivity is greater than 1 × 10 −9 S / cm and less than or equal to 1 × 10 −6 S / cm. This is preferable in that it has the effect of suppressing an increase in the series resistance component of the cell while increasing the light capture amount.

本発明の第２は、前記真性のアモルファス炭化ケイ素層は計測波長１０００ｎｍにおける屈折率Ｎｐｉが３．２以上３．４以下である、前記の薄膜シリコン系太陽電池、である。   The second aspect of the present invention is the above-described thin-film silicon solar cell, wherein the intrinsic amorphous silicon carbide layer has a refractive index Npi of 3.2 or more and 3.4 or less at a measurement wavelength of 1000 nm.

Ｎｐｉが３．２以上３．４以下である事によって、ｐ層と前記真性のアモルファスシリコン層間のバンドギャップ整合性が良いという効果を有する点で好ましい。   Npi of 3.2 or more and 3.4 or less is preferable in that the band gap matching between the p layer and the intrinsic amorphous silicon layer is good.

Ｎｉｂが３．１以上３．３以下である事によって、前記真性のアモルファス炭化ケイ素層とｉ層間のバンドギャップ整合性が良いという効果を有する点で好ましい。   When Nib is 3.1 or more and 3.3 or less, it is preferable in that it has an effect of good band gap matching between the intrinsic amorphous silicon carbide layer and the i layer.

屈折率が、Ｎｄ（２．５〜２．９）／Ｎｐｉ（３．２〜３．４）／Ｎｉｂ（３．１〜３．３）という順番であることによって、ｐ層／前記真性のアモルファス炭化ケイ素層／前記真性のアモルファスシリコン層／ｉ層の４層間のバンドギャップ整合性が良いという点で、好ましい。   When the refractive index is in the order of Nd (2.5 to 2.9) / Npi (3.2 to 3.4) / Nib (3.1 to 3.3), the p layer / the intrinsic amorphous It is preferable in terms of good band gap matching between the four layers of silicon carbide layer / the intrinsic amorphous silicon layer / i layer.

以下では薄膜а−Ｓｉ太陽電池を中心にして説明するが、本発明はこれだけに限定されるものではない。特に、а−Ｓｉ/μｃ−Ｓｉのタンデム型太陽電池等のようにа−Ｓｉセルが光入射側に配置された太陽電池では、а−Ｓｉセルの短波長感度を向上させてＪｓｃを向上させることは前述のように非常に重要である。   In the following description, the thin-film Si-Si solar cell will be mainly described, but the present invention is not limited to this. In particular, in a solar cell in which an а-Si cell is arranged on the light incident side, such as an а-Si / μc-Si tandem solar cell, the short wavelength sensitivity of the а-Si cell is improved to improve Jsc. This is very important as mentioned above.

以下の実施例、比較例で示す各層の物性（屈折率（計測波長：１０００ｎｍ）、明導電率）は、単膜（膜厚３０ｎｍ）をガラス基板（日本電気硝子製ＯＡ−１０基板）上に作製し、評価した結果の値である。屈折率は分光エリプソを用いて評価し、フィッティングモデルはＯＡ−１０／評価膜(Ｔａｕｃ−Ｌｏｒｅｎｔｚ ｍｏｄｅｌ)／表面酸化膜とした。導電率は、単膜上にコプラナー型電極を作製し評価した。   The physical properties (refractive index (measurement wavelength: 1000 nm), bright conductivity) of each layer shown in the following examples and comparative examples are as follows: a single film (thickness 30 nm) is formed on a glass substrate (OA 10 substrate manufactured by Nippon Electric Glass). It is the value of the result of making and evaluating. The refractive index was evaluated using a spectroscopic ellipso, and the fitting model was OA-10 / evaluation film (Tauc-Lorentz model) / surface oxide film. The electrical conductivity was evaluated by preparing a coplanar electrode on a single film.

界面層а−ｉ層は、ＯＡ−１０上に３０ｎｍ製膜し、ラマン分光法により評価した結果、アモルファスではなく微結晶であることが判っている。一方、実際にセルにしたときの界面層はアモルファスであることが透過型電子顕微鏡（ＴＥＭ）観察から判っている。通常、バンドギャップ整合性の観点や、界面層を製膜したときの下地層（ｐ層）へのダメージの観点から、界面層の製膜条件は単膜において微結晶となる条件を採用しない。   The interface layer i-i is formed into a film of 30 nm on OA-10 and evaluated by Raman spectroscopy. As a result, it is known that the interface layer а-i is a microcrystal instead of an amorphous layer. On the other hand, it is known from observation with a transmission electron microscope (TEM) that the interface layer in the actual cell is amorphous. Usually, from the viewpoint of bandgap matching and damage to the underlying layer (p layer) when the interface layer is formed, the film forming conditions for the interface layer do not adopt the conditions for forming a microcrystal in the single film.

一方、特許文献１にあるように、積極的に微結晶の界面層を用いる場合もあるが、この場合はセルの状態でも当該界面層が微結晶となるように条件を選択する。我々はそれらのどちらでもなく、単膜では微結晶だがセルではアモルファスという界面層а−ｉ層条件が薄膜а−Ｓｉ太陽電池適していることを見出し、採用している。   On the other hand, there is a case where a microcrystalline interface layer is positively used as disclosed in Patent Document 1. In this case, conditions are selected so that the interface layer becomes microcrystalline even in a cell state. We have found and adopted the interface layer а-i layer condition, which is neither one of them but microcrystalline in a single film but amorphous in a cell, and is suitable for a thin-film а-Si solar cell.

また、特許文献２にあるようにｐ層とｉ層の間の界面層を２層とし、なお且つ当該界面層に不純物（ボロン（Ｂ））を添加した場合、ｉ層製膜時に下地層であるｐ／ｉ界面層からＢが不純物としてｉ層に取り込まれ、発電効率を下げる原因となる。さらに、Ｂを添加することで当該ｐ／ｉ界面層での光吸収ロスも大きくなり、発電電流の低下に繋がる。   Further, as described in Patent Document 2, when the interface layer between the p layer and the i layer is made into two layers and an impurity (boron (B)) is added to the interface layer, an underlayer is formed at the time of forming the i layer. B is taken into the i layer as an impurity from a certain p / i interface layer, which causes a decrease in power generation efficiency. Furthermore, the addition of B increases the light absorption loss at the p / i interface layer, leading to a decrease in the generated current.

特許文献２ではｐ層／ｉ層界面の界面層を２層構造とし、このうち前記界面層のｐ層側は僅かにドーパント（ボロン（Ｂ））を添加し、前記界面層のｉ層側はさらに僅かなＢの添加或いは添加なしとすることで発電効率が改善するとしている。これに対して本発明では、ｐ層／ｉ層界面の界面層を２層構造とする点では共通するが、この界面層のｐ層側すなわち光入射側は真性のアモルファス炭化ケイ素層であり、この界面層のｉ層側すなわち光入射側から遠い側は真性のアモルファスシリコン層で有る点で、特許文献２とは異なる。   In Patent Document 2, the interface layer at the interface between the p layer and the i layer has a two-layer structure, of which the p layer side of the interface layer is slightly added with dopant (boron (B)), and the i layer side of the interface layer is Furthermore, it is said that power generation efficiency is improved by adding or not adding a little B. In contrast, the present invention is common in that the interface layer at the interface between the p layer and the i layer has a two-layer structure, but the p layer side of the interface layer, that is, the light incident side is an intrinsic amorphous silicon carbide layer, This interface layer is different from Patent Document 2 in that the i layer side, that is, the side far from the light incident side is an intrinsic amorphous silicon layer.

すなわち、ｐ層／ｉ層界面の界面層が、特許文献２ではわずかにボロンを添加しているためｐ型の性質を有するのに対して、本発明では真性である点が異なる。本発明では、ｐ層／ｉ層界面の界面層を真性である２層構造、すなわち、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層とすることによって、ボロン添加による膜中欠陥を抑制しながらｐ層／ｉ層間のバンドギャップを緩やかに繋ぐという顕著な効果を有する。このとき、上記２層目の真性アモルファスシリコン層は、それ単体で製膜した場合（単膜）では微結晶だがセル構造で用いた場合にはアモルファスという界面層а−ｉ層条件を採用した。通常、バンドギャップ整合性の観点や、界面層を製膜したときの下地層（ｐ層）へのダメージの観点から、当業者は界面層の製膜条件は単膜において微結晶となる条件を検討しないものであった。しかしながら、本発明においては、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層（単膜では微結晶となる条件）とからなる２層構造の層を採用することによって、当業者が容易に予想できないｐ層／ｉ層間のバンドギャップ整合性という効果を発現する。   That is, the interface layer at the interface between the p layer and the i layer has p-type properties because a slight amount of boron is added in Patent Document 2, but differs in that it is intrinsic in the present invention. In the present invention, the interface layer at the p layer / i layer interface is an intrinsic two-layer structure, that is, a layer having a two-layer structure comprising an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer in order from the light incident side. This has a remarkable effect of gently connecting the band gap between the p layer and the i layer while suppressing defects in the film due to boron addition. At this time, the second intrinsic amorphous silicon layer employed was an interface layer i-i layer condition in which it was microcrystalline when formed alone (single film) but amorphous when used in a cell structure. Usually, from the viewpoint of band gap matching and the viewpoint of damage to the underlying layer (p layer) when the interface layer is formed, those skilled in the art have determined that the film forming conditions for the interface layer are the conditions for forming a microcrystal in a single film. It was not considered. However, in the present invention, a person skilled in the art adopts a layer having a two-layer structure including an intrinsic amorphous silicon carbide layer and an intrinsic amorphous silicon layer (conditions for forming a microcrystal in a single film) in order from the light incident side. However, the effect of the band gap matching between the p layer / i layer, which cannot be easily predicted, is exhibited.

ｐ層とｉ層の間の界面層を２層とした特許には例えば、特開昭６２−１６５３７４などもある。当該特許では、界面層のカーボン（Ｃ）濃度に傾斜を持たせることを特徴としているが、下記比較例でも示すようにＣ濃度を傾斜させても短波長の光を充分に発電に寄与させられるわけではない。   For example, Japanese Patent Application Laid-Open No. 62-165374 discloses a patent in which two interface layers between the p layer and the i layer are used. The patent is characterized in that the carbon (C) concentration in the interface layer is inclined, but as shown in the following comparative example, even if the C concentration is inclined, short wavelength light can be sufficiently contributed to power generation. Do not mean.

なお、保持率（「光劣化後発電効率」／「初期発電効率」（％））算出のための加速劣化条件は、光照射強度：５ｓｕｎ、サンプル温度：５０℃、照射時間：２０時間とした。   The accelerated deterioration conditions for calculating the retention rate (“power generation efficiency after light degradation” / “initial power generation efficiency” (%)) were: light irradiation intensity: 5 sun, sample temperature: 50 ° C., irradiation time: 20 hours. .

（比較例１）
ｐ層として、屈折率Ｎｄ＝２．９６、明導電率＝４．４×１０−７Ｓ／ｃｍの膜を用いた。界面層ａ−ｉとして、屈折率Ｎｉｂ＝３．２４の膜を用いた。
図１に示すアモルファスシリコン太陽電池セルを作製した。まず、透明導電膜（ＴＣＯ）付きのガラス基板（旭硝子製ＶＵ基板（厚さ１．８ｍｍ））のＴＣＯ面上にｐ層をプラズマ化学気相成長（プラズマＣＶＤ）法により製膜した。このときの条件は、シラン（ＳｉＨ４）／水素（Ｈ２）／メタン（ＣＨ４）／ジボラン（Ｂ２Ｈ６）（水素希釈ジボラン。濃度：１０００ｐｐｍ。以下同様。）＝２７／１００／４０／２５０ｓｃｃｍ、基板温度＝１９０℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力１３３Ｐａ、膜厚８ｎｍとした。放電を維持したままガス条件をＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝２７／２００／０／０ｓｃｃｍに変更することで界面層ｐ層を１０ｎｍ製膜した（ガス、膜厚以外はｐ層と同じ製膜条件）。放電を維持したままＣＨ４、Ｂ２Ｈ６ガス流量を変更しているため、実質的にＣＨ４及びＢ２Ｈ６の濃度傾斜した界面層ｐ層が製膜されていることは容易に推測できる。次に、界面層ａ−ｉ層を製膜した。このときの条件は、ＳｉＨ４／Ｈ２＝２５／１９５０ｓｃｃｍ、基板温度＝２２５℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力４００Ｐａ、膜厚４ｎｍとした。放電を維持したまま光電変換層（ａ−ｉ層）、ｉ／ｎ界面層を製膜した。各々の条件は、ａ−ｉ層：ＳｉＨ４／Ｈ２＝２００／２０００ｓｃｃｍ、圧力５３３Ｐａ、膜厚２５０ｎｍ、ｉ／ｎ界面層：ＳｉＨ４／Ｈ２＝２５／１９５０ｓｃｃｍ、圧力４００Ｐａ、膜厚４ｎｍとした（いずれも基板温度、パワー密度は界面層ａ−ｉ層に同じ）。次に、ｎ層を製膜した。製膜条件は、ＳｉＨ４／Ｈ２／ホスフィン(ＰＨ３)（水素希釈ホスフィン。濃度：５０００ｐｐｍ。以下同様。）＝２０／３０００／１００ｓｃｃｍ、基板温度２１５℃、圧力２００Ｐａ、膜厚２０ｎｍとした。その後、裏面電極としてアルミドープ酸化亜鉛(ＡＺＯ)／銀(Ａｇ)を９０ｎｍ／３００ｎｍ製膜した。
このセルの初期効率は９．５％、分光光度計による短波長域(３００ｎｍ−５００ｎｍ)の積算発電電流密度Ｊｉは４．５ｍＡ／ｃｍ２だった。このセルを加速劣化装置により光劣化させた後の光劣化後効率は７．９％（保持率８３％）、光劣化後の分光光度計による短波長域の積算発電電流密度Ｊｄは３．７ｍＡ／ｃｍ２だった。 (Comparative Example 1)
As the p layer, a film having a refractive index Nd = 2.96 and a bright conductivity = 4.4 × 10 −7 S / cm was used. A film having a refractive index Nib = 3.24 was used as the interface layer a-i.
The amorphous silicon solar battery cell shown in FIG. 1 was produced. First, a p-layer was formed by plasma chemical vapor deposition (plasma CVD) on a TCO surface of a glass substrate (Asahi Glass VU substrate (thickness 1.8 mm)) with a transparent conductive film (TCO). The conditions at this time are silane (SiH 4 ) / hydrogen (H 2 ) / methane (CH 4 ) / diborane (B 2 H 6 ) (hydrogen diluted diborane, concentration: 1000 ppm, the same applies hereinafter) = 27/100/40 / 250 sccm, substrate temperature = 190 ° C., power density = 23 mW / cm 2 , pressure 133 Pa, film thickness 8 nm. The interface layer p layer was formed to 10 nm by changing the gas condition to SiH 4 / H 2 / CH 4 / B 2 H 6 = 27/200/0/0 sccm while maintaining the discharge (except for the gas and film thickness) Same film forming conditions as p layer). Since the CH 4 and B 2 H 6 gas flow rates are changed while the discharge is maintained, it is easily estimated that the interface layer p layer having a substantially gradient concentration of CH 4 and B 2 H 6 is formed. it can. Next, the interface layer ai layer was formed. The conditions at this time were SiH 4 / H 2 = 25/1950 sccm, substrate temperature = 225 ° C., power density = 23 mW / cm 2 , pressure 400 Pa, and film thickness 4 nm. A photoelectric conversion layer (ai layer) and an i / n interface layer were formed while maintaining the discharge. Each condition is as follows: ai layer: SiH 4 / H 2 = 200/2000 sccm, pressure 533 Pa, film thickness 250 nm, i / n interface layer: SiH 4 / H 2 = 25/1950 sccm, pressure 400 Pa, film thickness 4 nm (The substrate temperature and power density are the same as those of the interface layer ai). Next, an n layer was formed. The film forming conditions were SiH 4 / H 2 / phosphine (PH 3 ) (hydrogen diluted phosphine, concentration: 5000 ppm, the same applies hereinafter) = 20/3000/100 sccm, substrate temperature 215 ° C., pressure 200 Pa, and film thickness 20 nm. Thereafter, 90 nm / 300 nm of aluminum-doped zinc oxide (AZO) / silver (Ag) was formed as a back electrode.
The initial efficiency of this cell was 9.5%, and the cumulative generated current density Ji in the short wavelength region (300 nm-500 nm) by a spectrophotometer was 4.5 mA / cm 2 . The efficiency after photodegradation of the cell after photodegradation by an acceleration degrading device is 7.9% (retention rate 83%), and the integrated generation current density Jd in the short wavelength region by the spectrophotometer after photodegradation is 3.7 mA. / Cm 2 .

（実施例１）
ｐ層として、屈折率Ｎｄ＝２．８０、明導電率＝１．４×１０−６Ｓ／ｃｍの膜を用いた。界面層ａ−ＳｉＣとして、屈折率Ｎｐｉ＝３．３０の膜を用いた。界面層ａ−ｉとして、屈折率Ｎｉｂ＝３．１３の膜を用いた。 Example 1
As the p layer, a film having a refractive index Nd = 2.80 and a bright conductivity = 1.4 × 10 −6 S / cm was used. As the interface layer a-SiC, a film having a refractive index Npi = 3.30 was used. A film having a refractive index Nib = 3.13 was used as the interface layer a-i.

図１に示すアモルファスシリコン太陽電池セルを作製した。まず、透明導電膜（ＴＣＯ）付きのガラス基板（旭硝子製ＶＵ基板（厚さ１．８ｍｍ））のＴＣＯ面上にｐ層をプラズマＣＶＤ法により製膜した。このときの条件は、ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝１５／１０００／９０／１０００ｓｃｃｍ、基板温度＝１９０℃、パワー密度＝９ｍＷ／ｃｍ２、圧力１３３Ｐａ、膜厚１０ｎｍとした。ｐ層製膜後一度放電を切り、Ｂ２Ｈ６排気を待つために、界面層ａ−ＳｉＣのガス条件ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝３０／６００／６／０ｓｃｃｍにて３０秒間待機した。その後、界面層ａ−ＳｉＣを２ｎｍ製膜した(ガス、膜厚以外はｐ層と同じ製膜条件)。次に、界面層ａ−ｉを製膜した。このときの条件は、ＳｉＨ４／Ｈ２＝２５／２５００ｓｃｃｍ、基板温度＝２２５℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力４００Ｐａ、膜厚１３ｎｍとした。放電を維持したまま光電変換層(ａ−ｉ層)、ｉ／ｎ界面層を製膜し、各々の条件は比較例の場合と同じである。また、以降ｎ層、裏面電極を順次製膜し、これらの条件も比較例に同じとした。 The amorphous silicon solar battery cell shown in FIG. 1 was produced. First, a p-layer was formed on the TCO surface of a glass substrate with a transparent conductive film (TCO) (Asahi Glass VU substrate (thickness 1.8 mm)) by plasma CVD. The conditions at this time were SiH 4 / H 2 / CH 4 / B 2 H 6 = 15/1000/90/1000 sccm, substrate temperature = 190 ° C., power density = 9 mW / cm 2 , pressure 133 Pa, and film thickness 10 nm. . In order to cut off the discharge once after the p-layer deposition and wait for the B 2 H 6 exhaust, the gas condition of the interface layer a-SiC is SiH 4 / H 2 / CH 4 / B 2 H 6 = 30/600/6/0 sccm Waited for 30 seconds. Thereafter, an interface layer a-SiC was formed to 2 nm (the same film forming conditions as those of the p layer except for the gas and film thickness). Next, the interface layer ai was formed. The conditions at this time were SiH 4 / H 2 = 25/2500 sccm, substrate temperature = 225 ° C., power density = 23 mW / cm 2 , pressure 400 Pa, and film thickness 13 nm. The photoelectric conversion layer (a-i layer) and i / n interface layer were formed while maintaining the discharge, and the respective conditions were the same as in the comparative example. Further, the n layer and the back electrode were subsequently formed, and these conditions were the same as those in the comparative example.

このセルの初期効率は９．０％、分光光度計による短波長域(３００ｎｍ−５００ｎｍ)の積算発電電流密度Ｊｉは４．７ｍＡ／ｃｍ２だった。このセルを加速劣化装置により光劣化させた後の光劣化後効率は７．９％（保持率８８％）、光劣化後の分光光度計による短波長域の積算発電電流密度Ｊｄは４．４ｍＡ／ｃｍ２だった。比較例と比べて、光劣化後の効率は同等を維持しつつ、短波長域の積算発電電流密度を＋０．７ｍＡ／ｃｍ２改善した。 The initial efficiency of this cell was 9.0%, and the cumulative generated current density Ji in the short wavelength region (300 nm-500 nm) by a spectrophotometer was 4.7 mA / cm 2 . The efficiency after photodegradation of this cell after photodegradation by an acceleration degrading device is 7.9% (retention rate 88%), and the integrated generation current density Jd in the short wavelength region by the spectrophotometer after photodegradation is 4.4 mA. / Cm 2 . Compared to the comparative example, the integrated power generation current density in the short wavelength region was improved by +0.7 mA / cm 2 while maintaining the same efficiency after light degradation.

（実施例２）
ｐ層として、屈折率Ｎｄ＝２．５８、明導電率＝２．３×１０−８Ｓ／ｃｍの膜を用いた。界面層ａ−ＳｉＣとして、屈折率Ｎｐｉ＝３．３０の膜を用いた。界面層ａ−ｉとして、屈折率Ｎｉｂ＝３．２４の膜を用いた。 (Example 2)
As the p-layer, a film having a refractive index Nd = 2.58 and a bright conductivity = 2.3 × 10 −8 S / cm was used. As the interface layer a-SiC, a film having a refractive index Npi = 3.30 was used. A film having a refractive index Nib = 3.24 was used as the interface layer a-i.

図１に示すアモルファスシリコン太陽電池セルを作製した。まず、透明導電膜（ＴＣＯ）付きのガラス基板（旭硝子製ＶＵ基板（厚さ１．８ｍｍ））のＴＣＯ面上にｐ層をプラズマＣＶＤ法により製膜した。このときの条件は、ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝２７／６００／１００／２５０ｓｃｃｍ、基板温度＝１９０℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力１３３Ｐａ、膜厚１２ｎｍとした。ｐ層製膜後一度放電を切り、Ｂ２Ｈ６排気を待つために、界面層ａ−ＳｉＣのガス条件ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝２７／６００／１５／０ｓｃｃｍにて３０秒間待機した。その後、界面層ａ−ＳｉＣを２ｎｍ製膜した(ガス、膜厚以外はｐ層と同じ製膜条件)。次に、界面層ａ−ｉを製膜した。このときの条件は、ＳｉＨ４／Ｈ２＝２５／１９５０ｓｃｃｍ、基板温度＝２２５℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力４００Ｐａ、膜厚１０ｎｍとした。放電を維持したまま光電変換層(ａ−ｉ層)、ｉ／ｎ界面層を製膜し、各々の条件は比較例の場合と同じである。また、以降ｎ層、裏面電極を順次製膜し、これらの条件も比較例に同じとした。 The amorphous silicon solar battery cell shown in FIG. 1 was produced. First, a p-layer was formed on the TCO surface of a glass substrate with a transparent conductive film (TCO) (Asahi Glass VU substrate (thickness 1.8 mm)) by plasma CVD. The conditions at this time were SiH 4 / H 2 / CH 4 / B 2 H 6 = 27/600/100/250 sccm, substrate temperature = 190 ° C., power density = 23 mW / cm 2 , pressure 133 Pa, and film thickness 12 nm. . In order to turn off the discharge once after the p-layer deposition and wait for B 2 H 6 exhaust, the gas condition of the interface layer a-SiC is SiH 4 / H 2 / CH 4 / B 2 H 6 = 27/600/15/0 sccm Waited for 30 seconds. Thereafter, an interface layer a-SiC was formed to 2 nm (the same film forming conditions as those of the p layer except for the gas and film thickness). Next, the interface layer ai was formed. The conditions at this time were SiH 4 / H 2 = 25/1950 sccm, substrate temperature = 225 ° C., power density = 23 mW / cm 2 , pressure 400 Pa, and film thickness 10 nm. The photoelectric conversion layer (a-i layer) and i / n interface layer were formed while maintaining the discharge, and the respective conditions were the same as in the comparative example. Further, the n layer and the back electrode were subsequently formed, and these conditions were the same as those in the comparative example.

このセルの初期効率は８．６％、分光光度計による短波長域(３００ｎｍ−５００ｎｍ)の積算発電電流密度Ｊｉは４．７ｍＡ／ｃｍ２だった。このセルを加速劣化装置により光劣化させた後の光劣化後効率は７．５％（保持率８７％）、光劣化後の分光光度計による短波長域の積算発電電流密度Ｊｄは４．２ｍＡ／ｃｍ２だった。比較例と比べて、保持率を改善しつつ、短波長域の積算発電電流密度を＋０．５ｍＡ／ｃｍ２改善した。 The initial efficiency of this cell was 8.6%, and the cumulative generated current density Ji in the short wavelength region (300 nm-500 nm) by a spectrophotometer was 4.7 mA / cm 2 . The efficiency after photodegradation of the cell after photodegradation by an acceleration degrading device is 7.5% (retention rate 87%), and the integrated generation current density Jd in the short wavelength region by the spectrophotometer after photodegradation is 4.2 mA. / Cm 2 . Compared with the comparative example, the integrated power generation current density in the short wavelength region was improved by +0.5 mA / cm 2 while improving the retention rate.

（実施例３）
ｐ層として、屈折率Ｎｄ＝２．２６、明導電率＝１．０×１０−９Ｓ／ｃｍの膜を用いた。界面層ａ−ＳｉＣとして、屈折率Ｎｐｉ＝３．３０の膜を用いた。界面層ａ−ｉとして、屈折率Ｎｉｂ＝３．２４の膜を用いた。 (Example 3)
As the p layer, a film having a refractive index Nd = 2.26 and a bright conductivity = 1.0 × 10 −9 S / cm was used. As the interface layer a-SiC, a film having a refractive index Npi = 3.30 was used. A film having a refractive index Nib = 3.24 was used as the interface layer a-i.

図１に示すアモルファスシリコン太陽電池セルを作製した。まず、透明導電膜（ＴＣＯ）付きのガラス基板（旭硝子製ＶＵ基板（厚さ１．８ｍｍ））のＴＣＯ面上にｐ層をプラズマＣＶＤ法により製膜した。このときの条件は、ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝１５／１８０／８０／１５０ｓｃｃｍ、基板温度＝１９０℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力１３３Ｐａ、膜厚１２ｎｍとした。ｐ層製膜後一度放電を切り、Ｂ２Ｈ６排気を待つために、界面層ａ−ＳｉＣのガス条件ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝１５／３３０／９／０ｓｃｃｍにて３０秒間待機した。その後、界面層ａ−ＳｉＣを２ｎｍ製膜した(ガス、膜厚以外はｐ層と同じ製膜条件)。次に、界面層ａ−ｉを製膜した。このときの条件は、ＳｉＨ４／Ｈ２＝２５／１９５０ｓｃｃｍ、基板温度＝２２５℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力４００Ｐａ、膜厚１０ｎｍとした。放電を維持したまま光電変換層(ａ−ｉ層)、ｉ／ｎ界面層を製膜し、各々の条件は比較例の場合と同じである。また、以降ｎ層、裏面電極を順次製膜し、これらの条件も比較例に同じとした。 The amorphous silicon solar battery cell shown in FIG. 1 was produced. First, a p-layer was formed on the TCO surface of a glass substrate with a transparent conductive film (TCO) (Asahi Glass VU substrate (thickness 1.8 mm)) by plasma CVD. The conditions at this time were SiH 4 / H 2 / CH 4 / B 2 H 6 = 15/180/80/150 sccm, substrate temperature = 190 ° C., power density = 23 mW / cm 2 , pressure 133 Pa, film thickness 12 nm. . In order to turn off the discharge once after the p-layer deposition and wait for B 2 H 6 exhaust, the gas condition of the interface layer a-SiC is SiH 4 / H 2 / CH 4 / B 2 H 6 = 15/330/9/0 sccm Waited for 30 seconds. Thereafter, an interface layer a-SiC was formed to 2 nm (the same film forming conditions as those of the p layer except for the gas and film thickness). Next, the interface layer ai was formed. The conditions at this time were SiH 4 / H 2 = 25/1950 sccm, substrate temperature = 225 ° C., power density = 23 mW / cm 2 , pressure 400 Pa, and film thickness 10 nm. The photoelectric conversion layer (a-i layer) and i / n interface layer were formed while maintaining the discharge, and the respective conditions were the same as in the comparative example. Further, the n layer and the back electrode were subsequently formed, and these conditions were the same as those in the comparative example.

このセルの初期効率は６．３％、分光光度計による短波長域(３００ｎｍ−５００ｎｍ)の積算発電電流密度Ｊｉは４．６ｍＡ／ｃｍ２だった。ｐ層屈折率Ｎｄ、明導電率を前記まで低下させると、初期効率の時点で性能低下が顕著となり、太陽電池として適さない。 The initial efficiency of this cell was 6.3%, and the cumulative generated current density Ji in the short wavelength region (300 nm-500 nm) by a spectrophotometer was 4.6 mA / cm 2 . When the p-layer refractive index Nd and the bright conductivity are reduced to the above, the performance is significantly reduced at the initial efficiency, which is not suitable as a solar cell.

（実施例４）
ｐ層として、屈折率Ｎｄ＝２．５７、明導電率＝７．６×１０−８Ｓ／ｃｍの膜を用いた。界面層ａ−ＳｉＣとして、屈折率Ｎｐｉ＝３．３９の膜を用いた。界面層ａ−ｉとして、屈折率Ｎｉｂ＝３．２４の膜を用いた。 Example 4
A film having a refractive index Nd = 2.57 and a bright conductivity = 7.6 × 10 −8 S / cm was used as the p layer. A film having a refractive index Npi = 3.39 was used as the interface layer a-SiC. A film having a refractive index Nib = 3.24 was used as the interface layer a-i.

図１に示すアモルファスシリコン太陽電池セルを作製した。まず、透明導電膜（ＴＣＯ）付きのガラス基板（旭硝子製ＶＵ基板（厚さ１．８ｍｍ））のＴＣＯ面上にｐ層をプラズマＣＶＤ法により製膜した。このときの条件は、ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝３０／０／１８０／１０００ｓｃｃｍ、基板温度＝１９０℃、パワー密度＝９ｍＷ／ｃｍ２、圧力１３３Ｐａ、膜厚１０ｎｍとした。ｐ層製膜後一度放電を切り、Ｂ２Ｈ６排気を待つために、界面層ａ−ＳｉＣのガス条件ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝１５／３００／１／０ｓｃｃｍにて３０秒間待機した。その後、界面層ａ−ＳｉＣを２ｎｍ製膜した(ガス、膜厚以外はｐ層と同じ製膜条件)。次に、界面層ａ−ｉを製膜した。このときの条件は、ＳｉＨ４／Ｈ２＝２５／１９５０ｓｃｃｍ、基板温度＝２２５℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力４００Ｐａ、膜厚１０ｎｍとした。放電を維持したまま光電変換層(ａ−ｉ層)、ｉ／ｎ界面層を製膜し、各々の条件は比較例の場合と同じである。また、以降ｎ層、裏面電極を順次製膜し、これらの条件も比較例に同じとした。 The amorphous silicon solar battery cell shown in FIG. 1 was produced. First, a p-layer was formed on the TCO surface of a glass substrate with a transparent conductive film (TCO) (Asahi Glass VU substrate (thickness 1.8 mm)) by plasma CVD. The conditions at this time were SiH 4 / H 2 / CH 4 / B 2 H 6 = 30/0/180/1000 sccm, substrate temperature = 190 ° C., power density = 9 mW / cm 2 , pressure 133 Pa, and film thickness 10 nm. . In order to turn off the discharge once after the p-layer deposition and wait for B 2 H 6 exhaust, the gas condition of the interface layer a-SiC is SiH 4 / H 2 / CH 4 / B 2 H 6 = 15/300/1/0 sccm Waited for 30 seconds. Thereafter, an interface layer a-SiC was formed to 2 nm (the same film forming conditions as those of the p layer except for the gas and film thickness). Next, the interface layer ai was formed. The conditions at this time were SiH 4 / H 2 = 25/1950 sccm, substrate temperature = 225 ° C., power density = 23 mW / cm 2 , pressure 400 Pa, and film thickness 10 nm. The photoelectric conversion layer (a-i layer) and i / n interface layer were formed while maintaining the discharge, and the respective conditions were the same as in the comparative example. Further, the n layer and the back electrode were subsequently formed, and these conditions were the same as those in the comparative example.

このセルの初期効率は９．２％、分光光度計による短波長域(３００ｎｍ−５００ｎｍ)の積算発電電流密度Ｊｉは４．６ｍＡ／ｃｍ２だった。このセルを加速劣化装置により光劣化させた後の光劣化後効率は７．９％（保持率８６％）、光劣化後の分光光度計による短波長域の積算発電電流密度Ｊｄは４．３ｍＡ／ｃｍ２だった。比較例と比べて、保持率を改善しつつ、短波長域の積算発電電流密度を＋０．６ｍＡ／ｃｍ２改善した。 The initial efficiency of this cell was 9.2%, and the cumulative generated current density Ji in the short wavelength region (300 nm-500 nm) by a spectrophotometer was 4.6 mA / cm 2 . The efficiency after photodegradation of the cell after photodegradation by an acceleration degrading apparatus is 7.9% (retention rate 86%), and the integrated generation current density Jd in the short wavelength region by the spectrophotometer after photodegradation is 4.3 mA. / Cm 2 . Compared to the comparative example, the integrated power generation current density in the short wavelength region was improved by +0.6 mA / cm 2 while improving the retention rate.

（実施例５）
ｐ層として、屈折率Ｎｄ＝２．５７、明導電率＝７．６×１０−８Ｓ／ｃｍの膜を用いた。界面層ａ−ＳｉＣとして、屈折率Ｎｐｉ＝３．２８の膜を用いた。界面層ａ−ｉとして、屈折率Ｎｉｂ＝３．２４の膜を用いた。 (Example 5)
A film having a refractive index Nd = 2.57 and a bright conductivity = 7.6 × 10 −8 S / cm was used as the p layer. A film having a refractive index Npi = 3.28 was used as the interface layer a-SiC. A film having a refractive index Nib = 3.24 was used as the interface layer a-i.

図１に示すアモルファスシリコン太陽電池セルを作製した。まず、透明導電膜（ＴＣＯ）付きのガラス基板（旭硝子製ＶＵ基板（厚さ１．８ｍｍ））のＴＣＯ面上にｐ層をプラズマＣＶＤ法により製膜した。このときの条件は、ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝３０／０／１８０／１０００ｓｃｃｍ、基板温度＝１９０℃、パワー密度＝９ｍＷ／ｃｍ２、圧力１３３Ｐａ、膜厚１０ｎｍとした。ｐ層製膜後一度放電を切り、Ｂ２Ｈ６排気を待つために、界面層ａ−ＳｉＣのガス条件ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝１５／３００／６／０ｓｃｃｍにて３０秒間待機した。その後、界面層ａ−ＳｉＣを２ｎｍ製膜した(ガス、膜厚以外はｐ層と同じ製膜条件)。 次に、界面層ａ−ｉを製膜した。このときの条件は、ＳｉＨ４／Ｈ２＝２５／１９５０ｓｃｃｍ、基板温度＝２２５℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力４００Ｐａ、膜厚１０ｎｍとした。放電を維持したまま光電変換層(ａ−ｉ層)、ｉ／ｎ界面層を製膜し、各々の条件は比較例の場合と同じである。また、以降ｎ層、裏面電極を順次製膜し、これらの条件も比較例に同じとした。 The amorphous silicon solar battery cell shown in FIG. 1 was produced. First, a p-layer was formed on the TCO surface of a glass substrate with a transparent conductive film (TCO) (Asahi Glass VU substrate (thickness 1.8 mm)) by plasma CVD. The conditions at this time were SiH 4 / H 2 / CH 4 / B 2 H 6 = 30/0/180/1000 sccm, substrate temperature = 190 ° C., power density = 9 mW / cm 2 , pressure 133 Pa, and film thickness 10 nm. . In order to turn off the discharge once after the p-layer deposition and wait for B 2 H 6 exhaust, the gas condition of the interface layer a-SiC is SiH 4 / H 2 / CH 4 / B 2 H 6 = 15/300/6/0 sccm Waited for 30 seconds. Thereafter, an interface layer a-SiC was formed to 2 nm (the same film forming conditions as those of the p layer except for the gas and film thickness). Next, the interface layer ai was formed. The conditions at this time were SiH 4 / H 2 = 25/1950 sccm, substrate temperature = 225 ° C., power density = 23 mW / cm 2 , pressure 400 Pa, and film thickness 10 nm. The photoelectric conversion layer (a-i layer) and i / n interface layer were formed while maintaining the discharge, and the respective conditions were the same as in the comparative example. Further, the n layer and the back electrode were subsequently formed, and these conditions were the same as those in the comparative example.

このセルの初期効率は９．０％、分光光度計による短波長域(３００ｎｍ−５００ｎｍ)の積算発電電流密度Ｊｉは４．６ｍＡ／ｃｍ２だった。このセルを加速劣化装置により光劣化させた後の光劣化後効率は７．６％（保持率８４％）、光劣化後の分光光度計による短波長域の積算発電電流密度Ｊｄは４．３ｍＡ／ｃｍ２だった。比較例と比べて、保持率を改善しつつ、短波長域の積算発電電流密度を＋０．６ｍＡ／ｃｍ２改善した。 The initial efficiency of this cell was 9.0%, and the cumulative generated current density Ji in the short wavelength region (300 nm-500 nm) by a spectrophotometer was 4.6 mA / cm 2 . The efficiency after photodegradation of this cell after photodegradation by an acceleration degrading device is 7.6% (retention rate 84%), and the integrated generation current density Jd in the short wavelength region by the spectrophotometer after photodegradation is 4.3 mA. / Cm 2 . Compared to the comparative example, the integrated power generation current density in the short wavelength region was improved by +0.6 mA / cm 2 while improving the retention rate.

（実施例６）
ｐ層として、屈折率Ｎｄ＝２．５７、明導電率＝７．６×１０−８Ｓ／ｃｍの膜を用いた。界面層ａ−ＳｉＣとして、屈折率Ｎｐｉ＝３．１４の膜を用いた。界面層ａ−ｉとして、屈折率Ｎｉｂ＝３．２４の膜を用いた。 (Example 6)
A film having a refractive index Nd = 2.57 and a bright conductivity = 7.6 × 10 −8 S / cm was used as the p layer. A film having a refractive index Npi = 3.14 was used as the interface layer a-SiC. A film having a refractive index Nib = 3.24 was used as the interface layer a-i.

図１に示すアモルファスシリコン太陽電池セルを作製した。まず、透明導電膜（ＴＣＯ）付きのガラス基板（旭硝子製ＶＵ基板（厚さ１．８ｍｍ））のＴＣＯ面上にｐ層をプラズマＣＶＤ法により製膜した。このときの条件は、ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝３０／０／１８０／１０００ｓｃｃｍ、基板温度＝１９０℃、パワー密度＝９ｍＷ／ｃｍ２、圧力１３３Ｐａ、膜厚１０ｎｍとした。ｐ層製膜後一度放電を切り、Ｂ２Ｈ６排気を待つために、界面層ａ−ＳｉＣのガス条件ＳｉＨ４／Ｈ２／ＣＨ４／Ｂ２Ｈ６＝１５／３００／１５／０ｓｃｃｍにて３０秒間待機した。その後、界面層ａ−ＳｉＣを２ｎｍ製膜した(ガス、膜厚以外はｐ層と同じ製膜条件)。次に、界面層ａ−ｉを製膜した。このときの条件は、ＳｉＨ４／Ｈ２＝２５／１９５０ｓｃｃｍ、基板温度＝２２５℃、パワー密度＝２３ｍＷ／ｃｍ２、圧力４００Ｐａ、膜厚１０ｎｍとした。放電を維持したまま光電変換層(ａ−ｉ層)、ｉ／ｎ界面層を製膜し、各々の条件は比較例の場合と同じである。また、以降ｎ層、裏面電極を順次製膜し、これらの条件も比較例に同じとした。 The amorphous silicon solar battery cell shown in FIG. 1 was produced. First, a p-layer was formed on the TCO surface of a glass substrate with a transparent conductive film (TCO) (Asahi Glass VU substrate (thickness 1.8 mm)) by plasma CVD. The conditions at this time were SiH 4 / H 2 / CH 4 / B 2 H 6 = 30/0/180/1000 sccm, substrate temperature = 190 ° C., power density = 9 mW / cm 2 , pressure 133 Pa, and film thickness 10 nm. . In order to turn off the discharge once after the p-layer deposition and wait for B 2 H 6 exhaust, the gas condition of the interface layer a-SiC is SiH 4 / H 2 / CH 4 / B 2 H 6 = 15/300/15/0 sccm Waited for 30 seconds. Thereafter, an interface layer a-SiC was formed to 2 nm (the same film forming conditions as those of the p layer except for the gas and film thickness). Next, the interface layer ai was formed. The conditions at this time were SiH 4 / H 2 = 25/1950 sccm, substrate temperature = 225 ° C., power density = 23 mW / cm 2 , pressure 400 Pa, and film thickness 10 nm. The photoelectric conversion layer (a-i layer) and i / n interface layer were formed while maintaining the discharge, and the respective conditions were the same as in the comparative example. Further, the n layer and the back electrode were subsequently formed, and these conditions were the same as those in the comparative example.

このセルの初期効率は９．１％、分光光度計による短波長域(３００ｎｍ−５００ｎｍ)の積算発電電流密度Ｊｉは４．６ｍＡ／ｃｍ２だった。このセルを加速劣化装置により光劣化させた後の光劣化後効率は７．２％（保持率７９％）、光劣化後の分光光度計による短波長域の積算発電電流密度Ｊｄは４．３ｍＡ／ｃｍ２だった。界面層ａ−ＳｉＣの屈折率Ｎｐｉを前記まで低下させると、初期効率やＪｉ、Ｊｄは良好だが、保持率が低下し光劣化後の効率低下が顕著となってしまう。 The initial efficiency of this cell was 9.1%, and the cumulative generated current density Ji in the short wavelength region (300 nm-500 nm) by a spectrophotometer was 4.6 mA / cm 2 . The efficiency after photodegradation of this cell after photodegradation by an acceleration degrading device is 7.2% (retention rate 79%), and the integrated generation current density Jd in the short wavelength region by the spectrophotometer after photodegradation is 4.3 mA. / Cm 2 . When the refractive index Npi of the interface layer a-SiC is lowered to the above, the initial efficiency, Ji, and Jd are good, but the retention rate is lowered and the efficiency reduction after light deterioration becomes remarkable.

以上を表１にまとめる。   The above is summarized in Table 1.

Figure 2013008750
Figure 2013008750

比較例１と実施例１の比較から、Ｎｄの上限は２．９、ｐ層の明導電率上限は１×１０−６Ｓ／ｃｍ、Ｎｉｂの下限は３．１が好ましい。これにより、特許文献２の当業者の常識では、実施例１のようなデータは得られないところ、本発明では光劣化後の効率は比較例１と同等を維持しつつ、Ｊｄを＋０．７ｍＡ／ｃｍ２改善した。 From the comparison between Comparative Example 1 and Example 1, it is preferable that the upper limit of Nd is 2.9, the bright conductivity upper limit of the p layer is 1 × 10 −6 S / cm, and the lower limit of Nib is 3.1. Thus, according to the common sense of those skilled in the art of Patent Document 2, data as in Example 1 cannot be obtained. However, in the present invention, the efficiency after photodegradation is maintained equal to that in Comparative Example 1, and Jd is +0.7 mA. / Cm 2 improved.

比較例１と実施例２、実施例３の比較から、Ｎｄの下限は２．５、ｐ層の明導電率下限は１×１０−９Ｓ／ｃｍ、Ｎｉｂの上限は３．３が好ましい。これにより、特許文献２の当業者の常識では、実施例２のようなデータは得られないところ、本発明では比較例１と比べて保持率を改善しつつ、Ｊｄを＋０．５ｍＡ／ｃｍ２改善した。 From the comparison between Comparative Example 1, Example 2 and Example 3, it is preferable that the lower limit of Nd is 2.5, the lower limit of the bright conductivity of the p layer is 1 × 10 −9 S / cm, and the upper limit of Nib is 3.3. Thus, according to the common sense of those skilled in the art of Patent Document 2, data as in Example 2 cannot be obtained. However, in the present invention, the retention rate is improved as compared with Comparative Example 1, and Jd is +0.5 mA / cm 2. Improved.

比較例１と実施例４の比較から、Ｎｐｉの上限は３．４が好ましい。これにより、特許文献２の当業者の常識では、実施例４のようなデータは得られないところ、本発明では比較例１と比べて保持率を改善しつつ、Ｊｄを＋０．６ｍＡ／ｃｍ２改善した。 From a comparison between Comparative Example 1 and Example 4, the upper limit of Npi is preferably 3.4. Thus, according to the common sense of those skilled in the art of Patent Document 2, data as in Example 4 cannot be obtained. However, in the present invention, Jd is +0.6 mA / cm 2 while improving the retention rate as compared with Comparative Example 1. Improved.

比較例１と実施例５、実施例６の比較から、Ｎｐｉの下限は３．２が好ましい。これにより、特許文献２の当業者の常識では、実施例５のようなデータは得られないところ、本発明では比較例１と比べて保持率を改善しつつ、Ｊｄを＋０．６ｍＡ／ｃｍ２改善した。 From a comparison between Comparative Example 1, Example 5, and Example 6, the lower limit of Npi is preferably 3.2. Thus, according to common sense of those skilled in the art of Patent Document 2, data as in Example 5 cannot be obtained. However, in the present invention, Jd is +0.6 mA / cm 2 while improving the retention rate as compared with Comparative Example 1. Improved.

１ ガラス基板
２ 透明導電膜（ＴＣＯ）
３ ｐ層
４ ｐ／ｉ界面層１（ａ−ＳｉＣ層）
５ ｐ／ｉ界面層２（ａ−ｉ層）
６ 光電変換層（ｉ層）
７ ｎ層
８ 裏面透明導電膜（ＡＺＯ）
９ 裏面金属電極（Ａｇ） 1 Glass substrate 2 Transparent conductive film (TCO)
3 p layer 4 p / i interface layer 1 (a-SiC layer)
5 p / i interface layer 2 (ai layer)
6 Photoelectric conversion layer (i layer)
7 n layer 8 back transparent conductive film (AZO)
9 Back side metal electrode (Ag)

Claims (3)

ｐｉｎ接合を１以上含む薄膜シリコン系太陽電池であって、最も光入射側に位置するｐｉｎ接合のｉ層はアモルファスシリコンからなりｐ層は計測波長１０００ｎｍにおける屈折率Ｎｄが２．５以上２．９以下であり且つ明導電率が１×１０−９Ｓ／ｃｍより大きく１×１０−６Ｓ／ｃｍ以下であり、当該ｐ層とｉ層とにそれぞれ接する界面層が、光入射側から順に真性のアモルファス炭化ケイ素層と真性のアモルファスシリコン層とからなる２層構造の層であることを特徴とする、薄膜シリコン系太陽電池。 A thin-film silicon solar cell including one or more pin junctions, wherein the i layer of the pin junction located closest to the light incident side is made of amorphous silicon, and the p layer has a refractive index Nd of 2.5 or more and 2.9 at a measurement wavelength of 1000 nm. The interface layer that is in contact with the p layer and the i layer is intrinsic in order from the light incident side, and the bright conductivity is greater than 1 × 10 −9 S / cm and less than or equal to 1 × 10 −6 S / cm. A thin-film silicon solar cell, characterized in that it is a two-layered layer comprising an amorphous silicon carbide layer and an intrinsic amorphous silicon layer. 前記真性のアモルファス炭化ケイ素層は計測波長１０００ｎｍにおける屈折率Ｎｐｉが３．２以上３．４以下である、請求項１に記載の薄膜シリコン系太陽電池。 2. The thin-film silicon-based solar cell according to claim 1, wherein the intrinsic amorphous silicon carbide layer has a refractive index Npi of 3.2 or more and 3.4 or less at a measurement wavelength of 1000 nm. 前記真性のアモルファスシリコン層は、それ単体でガラス基板上に膜厚３０ｎｍの膜を製膜した場合には微結晶シリコンであり、且つその微結晶シリコンの計測波長１０００ｎｍにおける屈折率Ｎｉｂが３．１以上３．３以下である、請求項１または２に記載の薄膜シリコン系太陽電池。 The intrinsic amorphous silicon layer alone is microcrystalline silicon when a film having a thickness of 30 nm is formed on a glass substrate, and the refractive index Nib of the microcrystalline silicon at a measurement wavelength of 1000 nm is 3.1. The thin film silicon solar cell according to claim 1 or 2, wherein the thickness is 3.3 or less.
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