JPWO2014017354A1 - Photoelectric conversion device - Google Patents

Photoelectric conversion device Download PDF

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JPWO2014017354A1
JPWO2014017354A1 JP2014526873A JP2014526873A JPWO2014017354A1 JP WO2014017354 A1 JPWO2014017354 A1 JP WO2014017354A1 JP 2014526873 A JP2014526873 A JP 2014526873A JP 2014526873 A JP2014526873 A JP 2014526873A JP WO2014017354 A1 JPWO2014017354 A1 JP WO2014017354A1
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semiconductor layer
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山本　晃生
晃生 山本
祐介 宮道
祐介 宮道
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    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/072—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN heterojunction type
    • H01L31/0749—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN heterojunction type including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction solar cells
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Abstract

本発明は、光電変換装置の光電変換効率を向上させることを目的とする。光電変換装置１１は、電極層２と、電極層２上に配置された、１１族元素、１３族元素、カルコゲン元素および酸素元素を含むカルコパイライト構造の第１の半導体層３と、第１の半導体層３上に配置された、第１の半導体層３とｐｎ接合を形成する第２の半導体層４とを備えており、第１の半導体層３における酸素元素の原子濃度は、第１の半導体層３の厚みの中央部よりも第２の半導体層４側の上側表面部の方で低くなっている。An object of this invention is to improve the photoelectric conversion efficiency of a photoelectric conversion apparatus. The photoelectric conversion device 11 includes an electrode layer 2, a first semiconductor layer 3 having a chalcopyrite structure including a group 11 element, a group 13 element, a chalcogen element, and an oxygen element disposed on the electrode layer 2, The first semiconductor layer 3 disposed on the semiconductor layer 3 and the second semiconductor layer 4 forming a pn junction are provided. The atomic concentration of the oxygen element in the first semiconductor layer 3 is the first concentration The upper surface portion on the second semiconductor layer 4 side is lower than the central portion of the thickness of the semiconductor layer 3.

Description

本発明は、カルコパイライト構造を有するＩ−III−VI族化合物を含む光電変換装置に関する。   The present invention relates to a photoelectric conversion device including an I-III-VI group compound having a chalcopyrite structure.

太陽光発電などに使用される光電変換装置として、ＣＩＧＳなどのカルコパイライト構造を有するＩ−III−VI族化合物を光吸収層として用いたものがある（例えば、特開平８−３３０６１４号公報を参照）。Ｉ−III−VI族化合物は光吸収係数が高く、光電変換装置の薄膜化や大面積化や低コスト化に適しており、これを用いた次世代太陽電池の研究開発が進められている。   As a photoelectric conversion device used for photovoltaic power generation or the like, there is one using an I-III-VI group compound having a chalcopyrite structure such as CIGS as a light absorption layer (see, for example, JP-A-8-330614) ). The I-III-VI group compound has a high light absorption coefficient, and is suitable for thinning, large area, and cost reduction of a photoelectric conversion device, and research and development of next-generation solar cells using the compound are being promoted.

かかるＩ−III−VI族化合物を含む光電変換装置は、ガラスなどの基板の上に、金属電極などの下部電極層と、光吸収層と、バッファ層と、透明導電膜とをこの順に積層した光電変換セルを、平面的に複数並設した構成を有することによって構成される。複数の光電変換セルは、隣り合う一方の光電変換セルの透明導電膜と他方の下部電極層とを、接続導体で接続することで、電気的に直列接続されている。   In the photoelectric conversion device including such an I-III-VI group compound, a lower electrode layer such as a metal electrode, a light absorption layer, a buffer layer, and a transparent conductive film are laminated in this order on a substrate such as glass. A plurality of photoelectric conversion cells are arranged side by side in a plan view. The plurality of photoelectric conversion cells are electrically connected in series by connecting the transparent conductive film of one adjacent photoelectric conversion cell and the other lower electrode layer with a connection conductor.

Ｉ−III−VI族化合物を含む光電変換装置には、光電変換効率の向上が常に要求される。この光電変換効率は、光電変換装置において太陽光のエネルギーが電気エネルギーに変換される割合を示し、例えば、光電変換装置から出力される電気エネルギーの値が、光電変換装置に入射する太陽光のエネルギーの値で除されて、１００が乗じられることで導出される。   The photoelectric conversion device containing the I-III-VI group compound is always required to improve the photoelectric conversion efficiency. This photoelectric conversion efficiency indicates the rate at which sunlight energy is converted into electric energy in the photoelectric conversion device. For example, the value of the electric energy output from the photoelectric conversion device is the energy of sunlight incident on the photoelectric conversion device. It is derived by dividing by the value of and multiplied by 100.

本発明の１つの目的は、光電変換装置の光電変換効率を向上させることにある。   One object of the present invention is to improve the photoelectric conversion efficiency of a photoelectric conversion device.

本発明の一態様に係る光電変換装置は、電極層と、該電極層上に配置された、１１族元素、１３族元素、カルコゲン元素および酸素元素を含むカルコパイライト構造を有する第１の半導体層と、該第１の半導体層上に配置された、該第１の半導体層とｐｎ接合を形成する第２の半導体層とを備えており、前記第１の半導体層における酸素元素の原子濃度は、前記第１の半導体層の厚みの中央部よりも前記第２の半導体層側の上側表面部の方で低くなっている。   A photoelectric conversion device according to one embodiment of the present invention includes an electrode layer and a first semiconductor layer having a chalcopyrite structure including a group 11 element, a group 13 element, a chalcogen element, and an oxygen element, which are disposed over the electrode layer And a second semiconductor layer formed on the first semiconductor layer and forming a pn junction with the first semiconductor layer, and the atomic concentration of the oxygen element in the first semiconductor layer is The upper surface portion on the second semiconductor layer side is lower than the central portion of the thickness of the first semiconductor layer.

本発明の第１実施形態に係る光電変換装置の斜視図である。1 is a perspective view of a photoelectric conversion device according to a first embodiment of the present invention. 図１の光電変換装置の断面図である。It is sectional drawing of the photoelectric conversion apparatus of FIG. 第１の半導体層の酸素濃度の分布を示すグラフである。It is a graph which shows distribution of oxygen concentration of the 1st semiconductor layer. 第２実施形態に係る光電変換装置における第１の半導体層の酸素濃度の分布を示すグラフである。It is a graph which shows distribution of oxygen concentration of the 1st semiconductor layer in a photoelectric conversion device concerning a 2nd embodiment. 第３実施形態に係る光電変換装置における第１の半導体層のガリウム元素とインジウム元素との合計に対するガリウム元素の比率を示すグラフである。It is a graph which shows the ratio of the gallium element with respect to the sum total of the gallium element and indium element of the 1st semiconductor layer in the photoelectric conversion apparatus which concerns on 3rd Embodiment.

以下に本発明の一態様に係る光電変換装置について、図面を参照しながら詳細に説明する。   Hereinafter, a photoelectric conversion device according to one embodiment of the present invention will be described in detail with reference to the drawings.

＜第１実施形態に係る光電変換装置の構成＞
図１は、第１実施形態に係る光電変換装置の斜視図であり、図２はそのＸＺ断面図である。なお、図１および図２には、光電変換セル１０の配列方向（図１の図面視左右方向）をＸ軸方向とする右手系のＸＹＺ座標系を付している。光電変換装置１１は、基板１上に複数の光電変換セル１０が並べられて互いに電気的に接続されている。なお、図１においては図示の都合上、２つの光電変換セル１０のみを示しているが、実際の光電変換装置１１においては、図面左右方向（Ｘ軸方向）、あるいはさらにこれに垂直な方向（Ｙ軸方向）に、多数の光電変換セル１０が平面的に（２次元的に）配設されていてもよい。<Configuration of Photoelectric Conversion Device According to First Embodiment>
FIG. 1 is a perspective view of the photoelectric conversion device according to the first embodiment, and FIG. 2 is an XZ sectional view thereof. 1 and 2 have a right-handed XYZ coordinate system in which the arrangement direction of the photoelectric conversion cells 10 (the horizontal direction in the drawing in FIG. 1) is the X-axis direction. In the photoelectric conversion device 11, a plurality of photoelectric conversion cells 10 are arranged on the substrate 1 and are electrically connected to each other. In FIG. 1, only two photoelectric conversion cells 10 are shown for convenience of illustration. However, in an actual photoelectric conversion device 11, the horizontal direction in the drawing (X-axis direction) or a direction perpendicular to this ( A large number of photoelectric conversion cells 10 may be arranged in a plane (two-dimensionally) in the Y-axis direction).

図１、図２において、基板１上に複数の下部電極層２が平面配置されている。図１、図２において、複数の下部電極層２は、一方向（Ｘ軸方向）に間隔をあけて並べられた下部電極層２ａ〜２ｃを具備している。この下部電極層２ａ上から基板１上を経て下部電極層２ｂ上にかけて、第１の半導体層３が設けられている。また、第１の半導体層３上には、第１の半導体層３とは異なる導電型の第２の半導体層４が設けられている。さらに、下部電極層２ｂ上において、接続導体７が、第１の半導体層３の表面（側面）に沿って、または第１の半導体層３を貫通（分断）して設けられている。この接続導体７は、第２の半導体層４と下部電極層２ｂとを電気的に接続している。これら下部電極層２、第１の半導体層３、第２の半導体層４および上部電極層５によって、１つの光電変換セル１０が構成され、隣接する光電変換セル１０同士が接続導体７を介して直列接続されることによって、高出力の光電変換装置１１となる。なお、本実施形態における光電変換装置１１は、第２の半導体層４側から光が入射されるものを想定しているが、これに限定されず、基板１側から光が入射されるものであってもよい。   1 and 2, a plurality of lower electrode layers 2 are arranged in a plane on a substrate 1. 1 and 2, the plurality of lower electrode layers 2 include lower electrode layers 2a to 2c arranged at intervals in one direction (X-axis direction). A first semiconductor layer 3 is provided from the lower electrode layer 2a through the substrate 1 to the lower electrode layer 2b. In addition, a second semiconductor layer 4 having a conductivity type different from that of the first semiconductor layer 3 is provided on the first semiconductor layer 3. Furthermore, on the lower electrode layer 2 b, the connection conductor 7 is provided along the surface (side surface) of the first semiconductor layer 3 or penetrating (dividing) the first semiconductor layer 3. The connection conductor 7 electrically connects the second semiconductor layer 4 and the lower electrode layer 2b. The lower electrode layer 2, the first semiconductor layer 3, the second semiconductor layer 4, and the upper electrode layer 5 constitute one photoelectric conversion cell 10, and the adjacent photoelectric conversion cells 10 are connected to each other through the connection conductor 7. By being connected in series, the high-power photoelectric conversion device 11 is obtained. In addition, although the photoelectric conversion apparatus 11 in this embodiment assumes what enters light from the 2nd semiconductor layer 4 side, it is not limited to this, Light enters from the board | substrate 1 side. There may be.

基板１は、光電変換セル１０を支持するためのものである。基板１に用いられる材料としては、例えば、ガラス、セラミックス、樹脂および金属等が挙げられる。基板１としては、例えば、厚さ１〜３ｍｍ程度の青板ガラス（ソーダライムガラス）を用いることができる。   The substrate 1 is for supporting the photoelectric conversion cell 10. Examples of the material used for the substrate 1 include glass, ceramics, resin, and metal. As the substrate 1, for example, blue plate glass (soda lime glass) having a thickness of about 1 to 3 mm can be used.

下部電極層２（下部電極層２ａ、２ｂ、２ｃ）は、基板１上に設けられた、Ｍｏ（モリブデン）、Ａｌ（アルミニウム）、Ｔｉ（チタン）またはＡｕ（金）等の導電体である。下部電極層２は、スパッタリング法または蒸着法などの公知の薄膜形成手法を用いて、０．２μｍ〜１μｍ程度の厚みに形成される。   The lower electrode layer 2 (lower electrode layers 2a, 2b, 2c) is a conductor such as Mo (molybdenum), Al (aluminum), Ti (titanium), or Au (gold) provided on the substrate 1. The lower electrode layer 2 is formed to a thickness of about 0.2 μm to 1 μm using a known thin film forming method such as sputtering or vapor deposition.

第１の半導体層３は、例えば１μｍ〜３μｍ程度の厚みを有し、カルコパイライト構造のＩ−III−VI族化合物を主に有している。Ｉ−III−VI族化合物とは、１１族元素（Ｉ−Ｂ族元素ともいう）と１３族元素（III−Ｂ族元素ともいう）とカルコゲン元素との化合物である。なお、カルコゲン元素とは、１６族元素（VI−Ｂ族元素ともいう）のうち、Ｓ（イオウ）、Ｓｅ（セレン）、Ｔｅ（テルル）をいう。Ｉ−III−VI族化合物としては、例えば、ＣｕＩｎＳｅ２（二セレン化銅インジウム、ＣＩＳともいう）、Ｃｕ（Ｉｎ，Ｇａ）Ｓｅ２（二セレン化銅インジウム・ガリウム、ＣＩＧＳともいう）、Ｃｕ（Ｉｎ，Ｇａ）（Ｓｅ，Ｓ）２（二セレン・イオウ化銅インジウム・ガリウム、ＣＩＧＳＳともいう）が挙げられる。あるいは、第１の半導体層３は、薄膜の二セレン・イオウ化銅インジウム・ガリウム層を表面層として有する二セレン化銅インジウム・ガリウム等の多元化合物半導体薄膜にて構成されていてもよい。The first semiconductor layer 3 has a thickness of, for example, about 1 μm to 3 μm, and mainly includes a chalcopyrite structure I-III-VI group compound. The I-III-VI group compound is a compound of a group 11 element (also referred to as a group IB element), a group 13 element (also referred to as a group III-B element), and a chalcogen element. The chalcogen element refers to S (sulfur), Se (selenium), or Te (tellurium) among group 16 elements (also referred to as group VI-B elements). Examples of the I-III-VI group compound include CuInSe 2 (also referred to as copper indium selenide, CIS), Cu (In, Ga) Se 2 (also referred to as copper indium selenide / gallium, CIGS), Cu ( In, Ga) (Se, S) 2 (also referred to as diselene / copper indium / gallium / CIGSS). Alternatively, the first semiconductor layer 3 may be composed of a multi-component compound semiconductor thin film such as copper indium selenide / gallium having a thin film of selenite / copper indium sulfide / gallium layer as a surface layer.

また、第１の半導体層３は、さらに酸素（Ｏ）元素を含んでおり、酸素元素の原子濃度は、第１の半導体層３の厚み方向（Ｚ軸方向）の中央部よりも第２の半導体層４側の上側表面部の方で低くなっている。このような構成により、光電変換装置１１の光電変換効率が高くなる。つまり、第１の半導体層３中に酸素元素が含まれることによって、第１の半導体層３中の欠陥を酸素元素が埋めてキャリアの再結合を良好に低減できる。さらに、第１の半導体層３の第２の半導体層４側の上側表面部では、１１族元素が第２の半導体層４側へ拡散してアクセプターサイトが増加する傾向があるが、この上側表面部において酸素濃度を低くすることによってドナーサイトとして機能する１６族元素の空孔を増加させ、上記アクセプターサイトを低減させることができる。その結果、第１の半導体層３と第２の半導体層４とを良好にｐｎ接合させることができ、光電変換効率を高めることができる。   Further, the first semiconductor layer 3 further contains an oxygen (O) element, and the atomic concentration of the oxygen element is set to be higher than that of the central portion in the thickness direction (Z-axis direction) of the first semiconductor layer 3. It is lower on the upper surface portion on the semiconductor layer 4 side. With such a configuration, the photoelectric conversion efficiency of the photoelectric conversion device 11 is increased. That is, by including an oxygen element in the first semiconductor layer 3, defects in the first semiconductor layer 3 are filled with the oxygen element, and carrier recombination can be reduced well. Furthermore, in the upper surface portion of the first semiconductor layer 3 on the second semiconductor layer 4 side, the group 11 element tends to diffuse toward the second semiconductor layer 4 side and the acceptor site tends to increase. By reducing the oxygen concentration in the surface portion, the vacancies of group 16 elements that function as donor sites can be increased, and the acceptor sites can be reduced. As a result, the first semiconductor layer 3 and the second semiconductor layer 4 can be preferably pn-junctioned, and the photoelectric conversion efficiency can be increased.

第１の半導体層３は、少なくとも、第１の半導体層３を厚み方向（Ｚ軸方向）に３等分して、第２の半導体層４側の上側表面部と、中央部と、下部電極層２側の下側表面部とに分けた場合、上側表面部の酸素元素の原子濃度が、中央部の酸素元素の原子濃度よりも低ければよい。   The first semiconductor layer 3 includes at least an upper surface portion on the second semiconductor layer 4 side, a center portion, and a lower electrode by dividing the first semiconductor layer 3 into three equal parts in the thickness direction (Z-axis direction). When divided into the lower surface portion on the layer 2 side, the atomic concentration of the oxygen element on the upper surface portion should be lower than the atomic concentration of the oxygen element on the central portion.

酸素元素の原子濃度は、例えば、上記３等分された各層の断面において、任意の結晶粒における酸素濃度を、エネルギー分散型Ｘ線分析法（EDS：Energy Dispersive x-ray Spectroscopy）を用いて測定することにより求められる。あるいはスパッタリングで第１の半導体層３を深さ方向に削りながら２次イオン質量分析法（SIMS：Secondary Ion Mass Spectroscopy）を用いて測定してもよい。   The atomic concentration of the oxygen element is measured by, for example, energy dispersive x-ray spectroscopy (EDS) in any crystal grain in the cross section of each of the above three divided layers. Is required. Alternatively, measurement may be performed using secondary ion mass spectrometry (SIMS) while scraping the first semiconductor layer 3 in the depth direction by sputtering.

光電変換効率を高めるという観点からは、第１の半導体層３の中央部における酸素元素の原子濃度は、例えば２×１０２０〜３×１０２１ａｔｏｍｓ／ｃｍ３であってもよい。また、第２の半導体層４側の上側表面部における酸素元素の原子濃度は、中央部の酸素元素の原子濃度の０．１〜０．９倍であってもよく、より好ましくは０．１〜０．５倍であってもよい。From the viewpoint of increasing the photoelectric conversion efficiency, the atomic concentration of the oxygen element in the central portion of the first semiconductor layer 3 may be, for example, 2 × 10 20 to 3 × 10 21 atoms / cm 3 . Further, the atomic concentration of the oxygen element in the upper surface portion on the second semiconductor layer 4 side may be 0.1 to 0.9 times the atomic concentration of the oxygen element in the central portion, more preferably 0.1. It may be up to 0.5 times.

第１の半導体層３中での電荷移動をより良好にするという観点からは、第１の半導体層３の上側表面部における酸素元素の原子濃度は、第２の半導体層４に近づくほど漸次低くなっていてもよい。例えば、図３に第１の半導体層３の厚み方向における酸素元素の原子濃度の分布の一例が示されている。図３において、第１の半導体層３の上側表面部は第２の半導体層４からの距離が０〜０．６μｍの領域であり、この領域において酸素元素の原子濃度が第２の半導体層４に近づくほど漸次低くなっている。なお、図３においては、スパッタリングで第１の半導体層３を深さ方向に削りながらSIMSを用いて酸素元素の原子濃度の分布を測定したものであり、横軸は第２の半導体層４からの距離を示し、縦軸は酸素元素の原子濃度を示している。   From the viewpoint of improving charge transfer in the first semiconductor layer 3, the atomic concentration of the oxygen element in the upper surface portion of the first semiconductor layer 3 gradually decreases as it approaches the second semiconductor layer 4. It may be. For example, FIG. 3 shows an example of an atomic concentration distribution of oxygen elements in the thickness direction of the first semiconductor layer 3. In FIG. 3, the upper surface portion of the first semiconductor layer 3 is a region whose distance from the second semiconductor layer 4 is 0 to 0.6 μm, and in this region, the atomic concentration of the oxygen element is the second semiconductor layer 4. The closer it is, the lower it is. In FIG. 3, the atomic concentration distribution of the oxygen element is measured using SIMS while the first semiconductor layer 3 is being cut in the depth direction by sputtering, and the horizontal axis is from the second semiconductor layer 4. The vertical axis represents the atomic concentration of the oxygen element.

第２の半導体層４は、第１の半導体層３とは異なる第２導電型を有する半導体層である。第１の半導体層３および第２の半導体層４が電気的に接合することにより、電荷を良好に取り出すことが可能な光電変換層が形成される。例えば、第１の半導体層３がｐ型であれば、第２の半導体層４はｎ型である。第１の半導体層３がｎ型で、第２の半導体層４がｐ型であってもよい。なお、第２の半導体層４は、複数層から成るものであってもよく、複数層のうち少なくとも１層が高抵抗層であってもよい。   The second semiconductor layer 4 is a semiconductor layer having a second conductivity type different from that of the first semiconductor layer 3. When the first semiconductor layer 3 and the second semiconductor layer 4 are electrically joined to each other, a photoelectric conversion layer from which charges can be favorably extracted is formed. For example, if the first semiconductor layer 3 is p-type, the second semiconductor layer 4 is n-type. The first semiconductor layer 3 may be n-type and the second semiconductor layer 4 may be p-type. The second semiconductor layer 4 may be composed of a plurality of layers, and at least one of the plurality of layers may be a high resistance layer.

第２の半導体層４としては、ＣｄＳ、ＺｎＳ、ＺｎＯ、Ｉｎ２Ｓ３、Ｉｎ２Ｓｅ３、Ｉｎ（ＯＨ，Ｓ）、（Ｚｎ，Ｉｎ）（Ｓｅ，ＯＨ）、および（Ｚｎ，Ｍｇ）Ｏ等が挙げられる。第２の半導体層４は、例えばケミカルバスデポジション（ＣＢＤ）法等で１０〜２００ｎｍの厚みで形成される。なお、Ｉｎ（ＯＨ，Ｓ）とは、Ｉｎが水酸化物および硫化物として含まれる混晶化合物をいう。（Ｚｎ，Ｉｎ）（Ｓｅ，ＯＨ）は、ＺｎおよびＩｎがセレン化物および水酸化物として含まれる混晶化合物をいう。（Ｚｎ，Ｍｇ）Ｏは、ＺｎおよびＭｇが酸化物として含まれる化合物をいう。The second semiconductor layer 4 includes CdS, ZnS, ZnO, In 2 S 3 , In 2 Se 3 , In (OH, S), (Zn, In) (Se, OH), and (Zn, Mg) O. Etc. The second semiconductor layer 4 is formed with a thickness of 10 to 200 nm by, for example, a chemical bath deposition (CBD) method or the like. In (OH, S) refers to a mixed crystal compound containing In as a hydroxide and a sulfide. (Zn, In) (Se, OH) refers to a mixed crystal compound containing Zn and In as selenides and hydroxides. (Zn, Mg) O refers to a compound containing Zn and Mg as oxides.

図１、図２に示すように、第２の半導体層４上にさらに上部電極層５が設けられていてもよい。上部電極層５は、第２の半導体層４よりも抵抗率の低い層であり、第１の半導体層３および第２の半導体層４で生じた電荷を良好に取り出すことが可能となる。光電変換効率をより高めるという観点からは、上部電極層５の抵抗率が１Ω・ｃｍ未満でシート抵抗が５０Ω／□以下であってもよい。   As shown in FIGS. 1 and 2, an upper electrode layer 5 may be further provided on the second semiconductor layer 4. The upper electrode layer 5 is a layer having a lower resistivity than the second semiconductor layer 4, and it is possible to take out charges generated in the first semiconductor layer 3 and the second semiconductor layer 4 satisfactorily. From the viewpoint of further increasing the photoelectric conversion efficiency, the resistivity of the upper electrode layer 5 may be less than 1 Ω · cm and the sheet resistance may be 50 Ω / □ or less.

上部電極層５は、例えばＩＴＯ、ＺｎＯ等の０．０５〜３μｍの透明導電膜である。透光性および導電性を高めるため、上部電極層５は第２の半導体層４と同じ導電型の半導体で構成されてもよい。上部電極層５は、スパッタリング法、蒸着法または化学的気相成長（ＣＶＤ）法等で形成され得る。   The upper electrode layer 5 is a 0.05 to 3 μm transparent conductive film such as ITO or ZnO. In order to improve translucency and conductivity, the upper electrode layer 5 may be composed of a semiconductor having the same conductivity type as the second semiconductor layer 4. The upper electrode layer 5 can be formed by sputtering, vapor deposition, chemical vapor deposition (CVD), or the like.

また、図１、図２に示すように、上部電極層５上にさらに集電電極８が形成されていてもよい。集電電極８は、第１の半導体層３および第２の半導体層４で生じた電荷をさらに良好に取り出すためのものである。集電電極８は、例えば、図１に示すように、光電変換セル１０の一端から接続導体７にかけて線状に形成されている。これにより、第１の半導体層３および第４の半導体層４で生じた電流が上部電極層５を介して集電電極８に集電され、接続導体７を介して隣接する光電変換セル１０に良好に通電される。   Further, as shown in FIGS. 1 and 2, a collecting electrode 8 may be further formed on the upper electrode layer 5. The current collecting electrode 8 is for taking out charges generated in the first semiconductor layer 3 and the second semiconductor layer 4 more satisfactorily. For example, as shown in FIG. 1, the collector electrode 8 is formed in a linear shape from one end of the photoelectric conversion cell 10 to the connection conductor 7. As a result, the current generated in the first semiconductor layer 3 and the fourth semiconductor layer 4 is collected to the current collecting electrode 8 via the upper electrode layer 5, and to the adjacent photoelectric conversion cell 10 via the connection conductor 7. It is energized well.

集電電極８は、第１の半導体層３への光透過率を高めるとともに良好な導電性を有するという観点から、５０〜４００μｍの幅を有していてもよい。また、集電電極８は、枝分かれした複数の分岐部を有していてもよい。   The collector electrode 8 may have a width of 50 to 400 μm from the viewpoint of increasing the light transmittance to the first semiconductor layer 3 and having good conductivity. The current collecting electrode 8 may have a plurality of branched portions.

集電電極８は、例えば、Ａｇ等の金属粉を樹脂バインダー等に分散させた金属ペーストがパターン状に印刷され、これが硬化されることによって形成される。   The collector electrode 8 is formed, for example, by printing a metal paste in which a metal powder such as Ag is dispersed in a resin binder or the like in a pattern and curing it.

図１、図２において、接続導体７は、第１の半導体層３、第２の半導体層４および上部電極層５を貫通（分断）する溝内に設けられた導体である。接続導体７は、金属や導電ペースト等が用いられ得る。図１、図２においては、集電電極８を延伸して接続導体７が形成されているが、これに限定されない。例えば、上部電極層５が延伸したものであってもよい。   In FIGS. 1 and 2, the connection conductor 7 is a conductor provided in a groove that penetrates (divides) the first semiconductor layer 3, the second semiconductor layer 4, and the upper electrode layer 5. The connection conductor 7 can be made of metal, conductive paste, or the like. In FIG. 1 and FIG. 2, the collector electrode 8 is extended to form the connection conductor 7, but the present invention is not limited to this. For example, the upper electrode layer 5 may be stretched.

＜第１実施形態に係る光電変換装置の製造方法＞
次に、上記構成を有する光電変換装置１１の製造方法について説明する。ここでは第１の半導体層３がＣＩＧＳの場合について説明する。まず、ガラス等から成る基板１の主面に、スパッタリング法等を用いてＭｏ等から成る下部電極層２を所望のパターンに形成する。<Method for Manufacturing Photoelectric Conversion Device According to First Embodiment>
Next, a method for manufacturing the photoelectric conversion device 11 having the above configuration will be described. Here, a case where the first semiconductor layer 3 is CIGS will be described. First, the lower electrode layer 2 made of Mo or the like is formed in a desired pattern on the main surface of the substrate 1 made of glass or the like using a sputtering method or the like.

そして、この下部電極層２の上に、Ｉ−III−VI族化合物（ＣＩＧＳ）を構成する金属元素（Ｃｕ、ＩｎおよびＧａ）が有機錯体や有機酸塩として溶媒に溶解されて成る原料溶液を、塗布法等を用いて皮膜成形することによって第１の皮膜を形成する。そして、この第１の皮膜を水または酸素を含む雰囲気中で、例えば１５０〜３５０℃で加熱して、第１の皮膜中の有機成分を熱分解する。この熱分解の際、第１の皮膜中の金属元素の一部が酸化される（以下、第１の皮膜を形成し、有機成分を熱分解する工程を第１の工程という）。なお、第１の皮膜を熱分解する際の雰囲気としては、窒素等の不活性ガス中に、水蒸気または酸素が例えば分圧比で１０〜１０００ｐｐｍｖ程度含まれたものが用いられる。   On the lower electrode layer 2, a raw material solution in which metal elements (Cu, In and Ga) constituting the I-III-VI group compound (CIGS) are dissolved in an organic complex or an organic acid salt in a solvent is prepared. Then, the first film is formed by film forming using a coating method or the like. And this 1st membrane | film | coat is heated at 150-350 degreeC in the atmosphere containing water or oxygen, for example, and the organic component in a 1st membrane | film | coat is thermally decomposed. During the thermal decomposition, a part of the metal element in the first film is oxidized (hereinafter, the process of forming the first film and thermally decomposing the organic component is referred to as the first process). In addition, as an atmosphere at the time of thermally decomposing the 1st membrane | film | coat, what contained about 10-1000 ppmv of water vapor | steam or oxygen by partial pressure ratio in inert gas, such as nitrogen, is used.

次に、この熱分解した第１の皮膜上に、第１の皮膜の作製と同様にして、上記原料溶液を用いて第２の皮膜を形成し、この第２の皮膜中の有機成分を熱分解する（以下、第２の皮膜を形成し、有機成分を熱分解する工程を第２の工程という）。   Next, in the same manner as the production of the first film, a second film is formed on the thermally decomposed first film using the raw material solution, and the organic components in the second film are heated. Decompose (hereinafter, the process of forming the second film and thermally decomposing the organic component is referred to as the second process).

次に、この熱分解した第２の皮膜上に、上記原料溶液を用いて第３の皮膜を形成する。そして、この第３の皮膜を、上記の第２の工程よりも低い濃度の水または酸素を含む雰囲気中で加熱して、第３の皮膜中の有機成分を熱分解する。これによって第３の皮膜の酸素濃度が上記第２の皮膜よりも低くなる。   Next, a third film is formed on the thermally decomposed second film using the raw material solution. And this 3rd membrane | film | coat is heated in the atmosphere containing water or oxygen of a density | concentration lower than said 2nd process, and the organic component in a 3rd membrane | film | coat is thermally decomposed. As a result, the oxygen concentration of the third film becomes lower than that of the second film.

以上の工程により、厚み方向の中央部よりも上側表面部で酸素濃度が低くなった３層の皮膜の積層体が形成されたことになる。なお、皮膜は３層に限らず、２層あるいは４層以上であってもよい。各層の酸素濃度は、上述したように熱分解時の雰囲気中の水または酸素の濃度を変えることによって調整することができる。   Through the above steps, a three-layered film laminate having an oxygen concentration lower on the upper surface portion than the central portion in the thickness direction is formed. The coating is not limited to three layers, and may be two layers or four or more layers. As described above, the oxygen concentration of each layer can be adjusted by changing the concentration of water or oxygen in the atmosphere during pyrolysis.

次に、この皮膜の積層体を、セレンを含む雰囲気中で、例えば５００〜６００℃で加熱する。これによって、図３に示すような、Ｉ−III−VI族化合物（ＣＩＧＳ）および酸素元素を含み、厚み方向の中央部よりも上側表面部の方で酸素元素の原子濃度が低い第１の半導体層３を形成できる。   Next, the laminated body of this film is heated at, for example, 500 to 600 ° C. in an atmosphere containing selenium. Thereby, as shown in FIG. 3, the first semiconductor containing the I-III-VI group compound (CIGS) and the oxygen element and having a lower atomic concentration of the oxygen element in the upper surface portion than the central portion in the thickness direction. Layer 3 can be formed.

第１の半導体層３を形成した後、第１の半導体層３の上に、第２の半導体層４および上部電極層５を、ＣＢＤ法やスパッタリング法等で順次形成する。そして、第１の半導体層３、第２の半導体層４および上部電極層５をメカニカルスクライブ加工等によって加工し、接続導体７用の溝を形成する。   After forming the first semiconductor layer 3, the second semiconductor layer 4 and the upper electrode layer 5 are sequentially formed on the first semiconductor layer 3 by a CBD method, a sputtering method, or the like. Then, the first semiconductor layer 3, the second semiconductor layer 4, and the upper electrode layer 5 are processed by mechanical scribing or the like to form a groove for the connection conductor 7.

その後、上部電極層５上および溝内に、例えば、Ａｇなどの金属粉を樹脂バインダーなどに分散させた導電ペーストをパターン状に印刷し、これを加熱硬化させることで集電電極８および接続導体７を形成する。   Thereafter, on the upper electrode layer 5 and in the groove, for example, a conductive paste in which a metal powder such as Ag is dispersed in a resin binder or the like is printed in a pattern, and this is heated and cured to collect the collecting electrode 8 and the connecting conductor. 7 is formed.

最後に、接続導体７からずれた位置で、第１の半導体層３〜集電電極８をメカニカルスクライブ加工によって除去して複数の光電変換セル１０に分割することによって、図１および図２に示した光電変換装置１１を得ることができる。   Finally, the first semiconductor layer 3 to the current collecting electrode 8 are removed by mechanical scribing at a position shifted from the connection conductor 7 and divided into a plurality of photoelectric conversion cells 10, as shown in FIGS. 1 and 2. The photoelectric conversion device 11 can be obtained.

＜第２実施形態に係る光電変換装置の構成＞
本発明は上述の実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲内で種々の変更が施されることは何等差し支えない。例えば、上記第１実施形態の光電変換装置１１における第１の半導体層３に代えて、酸素元素の原子濃度の分布が異なる第１の半導体層３を採用してもよい。例えば、第１の半導体層３における酸素元素の原子濃度は、第１の半導体層３の厚みの中央部よりも上側表面部の方で低くなっていることに加え、さらに第１の半導体層３の厚み方向の中央部よりも下部電極層２側の下側表面部の方で低くなっていてもよい。これにより、下部電極層２の酸化によって高抵抗の異相が形成されるのを有効に抑制できる。また、第１の半導体層３の下部電極層２側の下側表面部では酸素濃度が低くなっていることによって、第１の半導体層３の価電子帯のエネルギー位置が下部電極層２の近傍で負電位側へずれる可能性もある。その結果、第１の半導体層３から下部電極層２への正孔の移動を良好にすることができる。<Configuration of Photoelectric Conversion Device According to Second Embodiment>
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, instead of the first semiconductor layer 3 in the photoelectric conversion device 11 of the first embodiment, the first semiconductor layer 3 having a different atomic element concentration distribution may be employed. For example, the atomic concentration of the oxygen element in the first semiconductor layer 3 is lower in the upper surface portion than in the central portion of the thickness of the first semiconductor layer 3, and in addition, the first semiconductor layer 3. The lower surface portion on the lower electrode layer 2 side may be lower than the central portion in the thickness direction. Thereby, it is possible to effectively suppress the formation of a high-resistance heterogeneous phase due to the oxidation of the lower electrode layer 2. In addition, since the oxygen concentration is low in the lower surface portion of the first semiconductor layer 3 on the lower electrode layer 2 side, the energy position of the valence band of the first semiconductor layer 3 is near the lower electrode layer 2. There is also a possibility of shifting to the negative potential side. As a result, the movement of holes from the first semiconductor layer 3 to the lower electrode layer 2 can be improved.

この場合、第１の半導体層３の下側表面部における酸素元素の原子濃度は、中央部の酸素元素の原子濃度の０．１〜０．９倍であってもよく、より好ましくは０．１〜０．５倍であってもよい。   In this case, the atomic concentration of the oxygen element in the lower surface portion of the first semiconductor layer 3 may be 0.1 to 0.9 times the atomic concentration of the oxygen element in the central portion, and more preferably is 0.1. It may be 1 to 0.5 times.

また、第１の半導体層３中での電荷移動をより良好にするという観点からは、第１の半導体層３の下側表面部における酸素元素の原子濃度は、下部電極層２に近づくほど漸次低くなっていてもよい。例えば、図４は、第２実施形態に係る光電変換装置１１における、第１の半導体層３の厚み方向の酸素元素の原子濃度の分布を示している。図４において、第１の半導体層３の下側表面部は第２の半導体層４からの距離が１．３〜１．９μｍの領域であり、この領域において酸素元素の原子濃度が下部電極層２に近づくほど漸次低くなっている。なお、図４においては、スパッタリングで第１の半導体層３を深さ方向に削りながらＳＩＭＳを用いて酸素元素の原子濃度の分布を測定したものであり、横軸は第２の半導体層４からの距離を示し、縦軸は酸素元素の原子濃度を示している。   Further, from the viewpoint of improving charge transfer in the first semiconductor layer 3, the atomic concentration of the oxygen element in the lower surface portion of the first semiconductor layer 3 gradually increases as it approaches the lower electrode layer 2. It may be lower. For example, FIG. 4 shows an atomic concentration distribution of oxygen elements in the thickness direction of the first semiconductor layer 3 in the photoelectric conversion device 11 according to the second embodiment. In FIG. 4, the lower surface portion of the first semiconductor layer 3 is a region whose distance from the second semiconductor layer 4 is 1.3 to 1.9 μm, and in this region, the atomic concentration of oxygen element is the lower electrode layer. The closer it is to 2, the lower it is. In FIG. 4, the distribution of the atomic concentration of the oxygen element is measured using SIMS while the first semiconductor layer 3 is cut in the depth direction by sputtering, and the horizontal axis is from the second semiconductor layer 4. The vertical axis represents the atomic concentration of the oxygen element.

このような酸素元素の原子濃度が厚みの中央部よりも上側表面部および下側表面部の方で低くなっている第１の半導体層３は、以下のようにして作製することができる。まず、上述した第１実施形態に係る光電変換装置１１の製造方法と同様に、下部電極層２の上に原料溶液を用いて第１の皮膜を形成した後、この第１の皮膜を水または酸素を含む雰囲気中で加熱して、第１の皮膜中の有機成分を熱分解する。   The first semiconductor layer 3 in which the atomic concentration of such an oxygen element is lower in the upper surface portion and the lower surface portion than in the central portion of the thickness can be produced as follows. First, similarly to the manufacturing method of the photoelectric conversion device 11 according to the first embodiment described above, a first film is formed on the lower electrode layer 2 using a raw material solution, and then the first film is washed with water or Heat in an atmosphere containing oxygen to thermally decompose the organic component in the first film.

次に、この熱分解した第１の皮膜上に原料溶液を用いて第２の皮膜を形成し、この第２の皮膜を水または酸素を含む雰囲気中で加熱して、第２の皮膜中の有機成分を熱分解する。ここで、第２の皮膜中の有機成分を熱分解する際の雰囲気の水または酸素の濃度を、第１の皮膜中の有機成分を熱分解する際の雰囲気の水または酸素の濃度よりも高くしておく。これによって、第２の皮膜の酸素濃度が上記第１の皮膜よりも高くなる。   Next, a second film is formed on the thermally decomposed first film using a raw material solution, and the second film is heated in an atmosphere containing water or oxygen, so that the second film Thermal decomposition of organic components. Here, the concentration of water or oxygen in the atmosphere when pyrolyzing the organic component in the second film is higher than the concentration of water or oxygen in the atmosphere when pyrolyzing the organic component in the first film. Keep it. Thereby, the oxygen concentration of the second film is higher than that of the first film.

次に、この熱分解した第２の皮膜上に原料溶液を用いて第３の皮膜を形成し、この第３の皮膜を水または酸素を含む雰囲気中で加熱して、第３の皮膜中の有機成分を熱分解する。ここで、第３の皮膜中の有機成分を熱分解する際の雰囲気の水または酸素の濃度を、第２の皮膜中の有機成分を熱分解する際の雰囲気の水または酸素の濃度よりも低くしておく。これによって、第３の皮膜の酸素濃度が上記第２の皮膜よりも低くなる。   Next, a third film is formed on the thermally decomposed second film by using a raw material solution, and the third film is heated in an atmosphere containing water or oxygen, Thermal decomposition of organic components. Here, the concentration of water or oxygen in the atmosphere when pyrolyzing the organic component in the third film is lower than the concentration of water or oxygen in the atmosphere when pyrolyzing the organic component in the second film. Keep it. Thereby, the oxygen concentration of the third film becomes lower than that of the second film.

以上の工程により、厚み方向の中央部よりも上側表面部および下側表面部で酸素濃度が低くなった３層の皮膜の積層体が形成されたことになる。そして、この皮膜の積層体を、セレンを含む雰囲気中で、例えば５００〜６００℃で加熱する。これによって、図４に示すような、厚み方向の中央部よりも上側表面部で酸素濃度が低いとともに、中央部よりも下側表面部で酸素濃度が低い第１の半導体層３を作製できる。   Through the above steps, a three-layered film laminate having an oxygen concentration lower in the upper surface portion and the lower surface portion than in the central portion in the thickness direction is formed. And the laminated body of this membrane | film | coat is heated at 500-600 degreeC in the atmosphere containing selenium, for example. As a result, as shown in FIG. 4, the first semiconductor layer 3 having a lower oxygen concentration at the upper surface portion than the central portion in the thickness direction and a lower oxygen concentration at the lower surface portion than the central portion can be produced.

＜第３実施形態に係る光電変換装置の構成＞
まだ、上記第１実施形態または第２実施形態の光電変換装置１１における第１の半導体層３において、１３族元素の原子濃度が厚み方向で変化していてもよい。例えば、第１の半導体層３が、ＣＩＧＳ等のようにインジウム（Ｉｎ）元素およびガリウム（Ｇａ）元素を含む場合、インジウム元素とガリウム元素との合計に対するガリウム元素の原子濃度比（ＭＧａ／（ＭＧａ＋ＭＩｎ））が、第１の半導体層３の中央部よりも下部電極層２側の下側表面部の方で高くなっていてもよい。この場合、第１の半導体層３の伝導帯のエネルギー位置を下部電極層２の近傍で負電位側へずらすことができる。その結果、第１の半導体層３から第２の半導体層４への電子の移動を良好にすることができる。その結果、光電変換装置１１の光電変換効率がさらに高くなる。なお、ＭＧａ／（ＭＧａ＋ＭＩｎ）において、ＭＧａはガリウム元素の原子濃度を表わし、ＭＩｎはインジウム元素の原子濃度を表わしている。<Configuration of Photoelectric Conversion Device According to Third Embodiment>
Still, in the first semiconductor layer 3 in the photoelectric conversion device 11 of the first embodiment or the second embodiment, the atomic concentration of the group 13 element may change in the thickness direction. For example, when the first semiconductor layer 3 includes an indium (In) element and a gallium (Ga) element, such as CIGS, the atomic concentration ratio of the gallium element to the sum of the indium element and the gallium element (M Ga / ( M Ga + M In )) may be higher on the lower surface portion on the lower electrode layer 2 side than on the central portion of the first semiconductor layer 3. In this case, the energy position of the conduction band of the first semiconductor layer 3 can be shifted to the negative potential side in the vicinity of the lower electrode layer 2. As a result, the movement of electrons from the first semiconductor layer 3 to the second semiconductor layer 4 can be improved. As a result, the photoelectric conversion efficiency of the photoelectric conversion device 11 is further increased. In M Ga / (M Ga + M In ), M Ga represents the atomic concentration of the gallium element, and M In represents the atomic concentration of the indium element.

この場合、第１の半導体層３の下側表面部において、インジウム元素とガリウム元素との合計に対するガリウム元素の原子濃度比（ＭＧａ／（ＭＧａ＋ＭＩｎ））が、下部電極層２に近づくほど漸次高くなっていると、第１の半導体層３中での電荷移動がさらに良好となる。例えば、図５に第１の半導体層３の厚み方向におけるインジウム元素とガリウム元素との合計に対するガリウム元素の原子濃度比の分布の一例が示されている。図５においては、横軸は第２の半導体層４からの距離を示し、縦軸はＭＧａ／（ＭＧａ＋ＭＩｎ）を示している。In this case, the atomic concentration ratio (M Ga / (M Ga + M In )) of the gallium element to the sum of the indium element and the gallium element approaches the lower electrode layer 2 at the lower surface portion of the first semiconductor layer 3. As the value gradually increases, the charge transfer in the first semiconductor layer 3 is further improved. For example, FIG. 5 shows an example of the distribution of the atomic concentration ratio of the gallium element to the sum of the indium element and the gallium element in the thickness direction of the first semiconductor layer 3. In FIG. 5, the horizontal axis indicates the distance from the second semiconductor layer 4, and the vertical axis indicates M Ga / (M Ga + M In ).

このような原子濃度比（ＭＧａ／（ＭＧａ＋ＭＩｎ））が厚み方向で異なる第１の半導体層３は、インジウム元素とガリウム元素の濃度比を変えた原料を用いて皮膜を積層させることによって作製できる。The first semiconductor layer 3 having such an atomic concentration ratio (M Ga / (M Ga + M In )) different in the thickness direction is formed by stacking a film using a raw material in which the concentration ratio of indium element and gallium element is changed. Can be produced.

次に、本発明の一実施形態に係る光電変換装置１１について、具体例を示して説明する。   Next, the photoelectric conversion device 11 according to an embodiment of the present invention will be described with a specific example.

（評価試料１の作製）
まず、第１の半導体層３を形成するための原料溶液を作製した。原料溶液としては、米国特許第６９９２２０２号明細書に基づいて作製した単一源前駆体をピリジンに溶解したものを用いた。なお、この単一源前駆体としては、ＣｕとＩｎとフェニルセレノールとが１つの錯体分子を形成したものと、ＣｕとＧａとフェニルセレノールとが１つの錯体分子を形成したものとの混合体を用いた。(Preparation of evaluation sample 1)
First, a raw material solution for forming the first semiconductor layer 3 was produced. As the raw material solution, a solution obtained by dissolving a single source precursor prepared in accordance with US Pat. No. 6,992,202 in pyridine was used. In addition, as this single source precursor, Cu, In, and phenyl selenol formed one complex molecule, and Cu, Ga, and phenyl selenol formed one complex molecule. Using the body.

次に、ガラスによって構成される基板１の表面にＭｏからなる下部電極層２が成膜されたものを用意し、この下部電極層２の上に原料溶液をブレード法によって塗布して第１の皮膜を形成した。そして、この第１の皮膜を、窒素ガス中に水（水蒸気）が分圧比で２００ｐｐｍｖ含まれる雰囲気において、２８０℃で１０分加熱して第１の皮膜に含まれる有機成分を熱分解した。   Next, a substrate 1 made of glass with a lower electrode layer 2 made of Mo is prepared, and a raw material solution is applied onto the lower electrode layer 2 by a blade method to form a first electrode. A film was formed. Then, this first film was heated at 280 ° C. for 10 minutes in an atmosphere containing 200 ppmv of water (water vapor) in a nitrogen gas partial pressure ratio to thermally decompose the organic components contained in the first film.

次に、この熱分解した第１の皮膜上に上記原料溶液をブレード法によって塗布して、第２の皮膜を形成した。そして、この第２の皮膜を、窒素ガス中に水（水蒸気）が分圧比で２００ｐｐｍｖ含まれる雰囲気において２８０℃で１０分加熱して、第２の皮膜に含まれる有機成分を熱分解した。   Next, the raw material solution was applied onto the thermally decomposed first film by a blade method to form a second film. And this 2nd membrane | film | coat was heated for 10 minutes at 280 degreeC in the atmosphere where water (water vapor | steam) is contained in nitrogen gas by partial pressure ratio at 200 ppmv, and the organic component contained in the 2nd membrane | film | coat was thermally decomposed.

次に、この熱分解した第２の皮膜上に上記原料溶液をブレード法によって塗布して、第３の皮膜を形成した。そして、この第３の皮膜を、窒素ガス中に水（水蒸気）が分圧比で８０ｐｐｍｖ含まれる雰囲気において２８０℃で１０分加熱して、第３の皮膜に含まれる有機成分を熱分解した。   Next, the raw material solution was applied onto the thermally decomposed second film by a blade method to form a third film. Then, this third film was heated at 280 ° C. for 10 minutes in an atmosphere containing water (steam) in nitrogen gas at a partial pressure ratio of 80 ppmv to thermally decompose the organic components contained in the third film.

次に、この第１の皮膜、第２の皮膜および第３の皮膜の積層体を、水素ガス中にセレン蒸気が分圧比で２０ｐｐｍｖ含まれる雰囲気において５５０℃で１時間加熱して、主としてＣＩＧＳを含み、厚さが２μｍの第１の半導体層３を形成した。   Next, the laminated body of the first film, the second film, and the third film is heated at 550 ° C. for 1 hour in an atmosphere in which hydrogen gas contains selenium vapor at a partial pressure ratio of 20 ppmv. In addition, a first semiconductor layer 3 having a thickness of 2 μm was formed.

次に、第１の半導体層３までが形成された基板を、塩化インジウムとチオアセトアミドが溶解された水溶液に浸漬することで、第１の半導体層３の上に厚さが５０ｎｍのＩｎ２Ｓ３を含む第２の半導体層４を形成した。Next, the substrate on which up to the first semiconductor layer 3 is formed is immersed in an aqueous solution in which indium chloride and thioacetamide are dissolved, whereby an In 2 S film having a thickness of 50 nm is formed on the first semiconductor layer 3. A second semiconductor layer 4 including 3 was formed.

そして、第２の半導体層４上に、スパッタリング法によってＡＺＯからなる上部電極層５を形成して、評価試料１としての光電変換装置１１とした。   Then, the upper electrode layer 5 made of AZO was formed on the second semiconductor layer 4 by a sputtering method, and the photoelectric conversion device 11 as the evaluation sample 1 was obtained.

このようにして作製した評価試料１の第１の半導体層３を第２の半導体層４側からエッチングしながらＳＩＭＳ測定することにより、第１の半導体層３中の酸素元素の分布を測定した。その結果を図３に示す。これより、第１の半導体層３の厚み方向の中央部に比べて、第２の半導体層４側の上側表面部における酸素濃度が低くなっていることがわかった。   The distribution of the oxygen element in the first semiconductor layer 3 was measured by performing SIMS measurement while etching the first semiconductor layer 3 of the evaluation sample 1 thus manufactured from the second semiconductor layer 4 side. The result is shown in FIG. From this, it was found that the oxygen concentration in the upper surface portion on the second semiconductor layer 4 side was lower than the central portion in the thickness direction of the first semiconductor layer 3.

（評価試料２の作製）
次に、評価試料２を作製した。評価試料２は、第１の半導体層３の作製以外は上記評価試料１の作製と同様にして作製した。評価試料２の第１の半導体層３の作製では、第１の皮膜〜第３の皮膜の熱分解の条件を以下のようにした。(Preparation of evaluation sample 2)
Next, evaluation sample 2 was prepared. The evaluation sample 2 was manufactured in the same manner as the evaluation sample 1 except that the first semiconductor layer 3 was manufactured. In the production of the first semiconductor layer 3 of the evaluation sample 2, the conditions for thermal decomposition of the first film to the third film were as follows.

第１の皮膜の熱分解の条件は、窒素ガス中に水（水蒸気）が分圧比で８０ｐｐｍｖ含まれる雰囲気において、２８０℃で１０分加熱する条件とした。   The conditions for the thermal decomposition of the first film were the conditions of heating at 280 ° C. for 10 minutes in an atmosphere in which water (water vapor) was contained in nitrogen gas at a partial pressure ratio of 80 ppmv.

また、第２の皮膜の熱分解の条件は、窒素ガス中に水（水蒸気）が分圧比で２００ｐｐｍｖ含まれる雰囲気において、２８０℃で１０分加熱する条件とした。   Moreover, the conditions for the thermal decomposition of the second film were the conditions of heating at 280 ° C. for 10 minutes in an atmosphere containing 200 ppmv of water (water vapor) in a partial pressure ratio in nitrogen gas.

また、第３の皮膜の熱分解の条件は、窒素ガス中に水（水蒸気）が分圧比で８０ｐｐｍｖ含まれる雰囲気において、２８０℃で１０分加熱する条件とした。   Moreover, the conditions for the thermal decomposition of the third film were such that the nitrogen gas was heated at 280 ° C. for 10 minutes in an atmosphere containing water (water vapor) at a partial pressure ratio of 80 ppmv.

このようにして作製した評価試料２の第１の半導体層３を第２の半導体層４側からエッチングしながらＳＩＭＳ測定することにより、第１の半導体層３中の酸素元素の分布を測定した。その結果を図４に示す。これより、第１の半導体層３の厚み方向の中央部に比べて、第２の半導体層４側の上側表面部および下部電極層２側の下側表面部における酸素濃度が低くなっていることがわかった。   The distribution of the oxygen element in the first semiconductor layer 3 was measured by performing SIMS measurement while etching the first semiconductor layer 3 of the evaluation sample 2 thus manufactured from the second semiconductor layer 4 side. The result is shown in FIG. Accordingly, the oxygen concentration in the upper surface portion on the second semiconductor layer 4 side and the lower surface portion on the lower electrode layer 2 side is lower than the central portion in the thickness direction of the first semiconductor layer 3. I understood.

（比較試料の作製）
次に、比較試料を作製した。比較試料は、第１の半導体層の作製以外は上記評価試料１の作製と同様にして作製した。比較試料の第１の半導体層の作製では、第１の皮膜〜第３の皮膜の熱分解を、水を含まない雰囲気で、各層とも同じ条件で行なった。すなわち、第１皮膜〜第３の皮膜のそれぞれの熱分解工程において、各皮膜を窒素ガス雰囲気において２８０℃で１０分加熱して、各皮膜に含まれる有機成分を熱分解した。(Production of comparative sample)
Next, a comparative sample was produced. The comparative sample was manufactured in the same manner as the evaluation sample 1 except that the first semiconductor layer was manufactured. In the production of the first semiconductor layer of the comparative sample, the first coating to the third coating were thermally decomposed under the same conditions for each layer in an atmosphere not containing water. That is, in each thermal decomposition step of the first film to the third film, each film was heated at 280 ° C. in a nitrogen gas atmosphere for 10 minutes to thermally decompose organic components contained in each film.

このようにして作製した比較試料の第１の半導体層を第２の半導体層側からエッチングしながらＳＩＭＳ測定することにより、第１の半導体層中の酸素元素の分布を測定した。その結果、比較試料では、酸素元素は微量しか含まれておらず、第１の半導体層の厚み方向における濃度の違いは観察されなかった。   The distribution of oxygen element in the first semiconductor layer was measured by performing SIMS measurement while etching the first semiconductor layer of the comparative sample thus fabricated from the second semiconductor layer side. As a result, the comparative sample contained only a trace amount of oxygen element, and no difference in concentration in the thickness direction of the first semiconductor layer was observed.

（光電変換効率の測定）
このようにして作製した評価試料１、評価試料２および比較試料の光電変換効率の測定を以下のように実施した。いわゆる定常光ソーラシミュレーターを用いて、光電変換装置の受光面に対する光の照射強度が１００ｍＷ／ｃｍ2であり且つＡＭ（エアマス）が１．５である条件下での光電変換効率を測定した。その結果、比較試料の光電変換効率は１０．０％であったのに対し、評価試料１の光電変換効率は１３．５％であり、評価試料２の光電変換効率は１３．８％であり、比較試料よりも高くなっていることが分かった。(Measurement of photoelectric conversion efficiency)
The photoelectric conversion efficiency of the evaluation sample 1, the evaluation sample 2, and the comparative sample thus produced was measured as follows. Using a so-called steady light solar simulator, the photoelectric conversion efficiency was measured under the conditions where the light irradiation intensity on the light receiving surface of the photoelectric conversion device was 100 mW / cm 2 and AM (air mass) was 1.5. As a result, the photoelectric conversion efficiency of the comparative sample was 10.0%, whereas the photoelectric conversion efficiency of the evaluation sample 1 was 13.5%, and the photoelectric conversion efficiency of the evaluation sample 2 was 13.8%. It was found to be higher than the comparative sample.

１：基板
２、２ａ、２ｂ、２ｃ：下部電極層
３：第１の半導体層
４：第２の半導体層
７：接続導体
１０：光電変換セル
１１：光電変換装置1: substrate 2, 2a, 2b, 2c: lower electrode layer 3: first semiconductor layer 4: second semiconductor layer 7: connection conductor 10: photoelectric conversion cell 11: photoelectric conversion device

Claims (5)

電極層と、
該電極層上に配置された、１１族元素、１３族元素、カルコゲン元素および酸素元素を含むカルコパイライト構造を有する第１の半導体層と、
該第１の半導体層上に配置された、該第１の半導体層とｐｎ接合を形成する第２の半導体層とを備えており、
前記第１の半導体層における酸素元素の原子濃度は、前記第１の半導体層の厚みの中央部よりも前記第２の半導体層側の上側表面部の方で低くなっている光電変換装置。An electrode layer;
A first semiconductor layer having a chalcopyrite structure including a group 11 element, a group 13 element, a chalcogen element, and an oxygen element, disposed on the electrode layer;
A second semiconductor layer disposed on the first semiconductor layer and forming a pn junction with the first semiconductor layer;
The photoelectric conversion device in which the atomic concentration of the oxygen element in the first semiconductor layer is lower in the upper surface portion on the second semiconductor layer side than in the central portion of the thickness of the first semiconductor layer. 前記第１の半導体層の前記上側表面部における酸素元素の原子濃度は、前記第２の半導体層に近づくほど漸次低くなっている、請求項１に記載の光電変換装置。   2. The photoelectric conversion device according to claim 1, wherein an atomic concentration of an oxygen element in the upper surface portion of the first semiconductor layer gradually decreases as the second semiconductor layer is approached. 前記第１の半導体層における酸素元素の原子濃度は、さらに前記第１の半導体層の厚みの中央部よりも前記電極層側の下側表面部の方で低くなっている、請求項１または２に記載の光電変換装置。   The atomic concentration of the oxygen element in the first semiconductor layer is further lower in the lower surface portion on the electrode layer side than in the central portion of the thickness of the first semiconductor layer. The photoelectric conversion device described in 1. 前記第１の半導体層の前記下側表面部における酸素元素の原子濃度は、前記電極層に近づくほど漸次低くなっている、請求項３に記載の光電変換装置。   4. The photoelectric conversion device according to claim 3, wherein the atomic concentration of the oxygen element in the lower surface portion of the first semiconductor layer gradually decreases as the electrode layer approaches. 5. 前記第１の半導体層は、前記１３族元素としてインジウム元素およびガリウム元素を含み、インジウム元素とガリウム元素との合計に対するガリウム元素の原子濃度比が、前記第１の半導体層の中央部よりも前記電極層側の下側表面部の方で高くなっている、請求項１乃至４のいずれかに記載の光電変換装置。   The first semiconductor layer includes an indium element and a gallium element as the group 13 element, and the atomic concentration ratio of the gallium element to the sum of the indium element and the gallium element is higher than that of the central portion of the first semiconductor layer. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device is higher at a lower surface portion on the electrode layer side.
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