JPH1012902A - Photovoltaic cell - Google Patents
Photovoltaic cellInfo
- Publication number
- JPH1012902A JPH1012902A JP8166005A JP16600596A JPH1012902A JP H1012902 A JPH1012902 A JP H1012902A JP 8166005 A JP8166005 A JP 8166005A JP 16600596 A JP16600596 A JP 16600596A JP H1012902 A JPH1012902 A JP H1012902A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- type
- type layer
- impurity
- buffer layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000012535 impurity Substances 0.000 claims abstract description 32
- 230000003287 optical effect Effects 0.000 claims abstract description 20
- 229910021417 amorphous silicon Inorganic materials 0.000 claims description 24
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 claims description 13
- 239000004065 semiconductor Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 7
- 238000006243 chemical reaction Methods 0.000 abstract description 29
- 230000005684 electric field Effects 0.000 abstract description 14
- 230000007423 decrease Effects 0.000 abstract description 10
- 239000000969 carrier Substances 0.000 abstract description 6
- 230000003247 decreasing effect Effects 0.000 abstract description 4
- XUKUURHRXDUEBC-SXOMAYOGSA-N (3s,5r)-7-[2-(4-fluorophenyl)-3-phenyl-4-(phenylcarbamoyl)-5-propan-2-ylpyrrol-1-yl]-3,5-dihydroxyheptanoic acid Chemical compound C=1C=CC=CC=1C1=C(C=2C=CC(F)=CC=2)N(CC[C@@H](O)C[C@H](O)CC(O)=O)C(C(C)C)=C1C(=O)NC1=CC=CC=C1 XUKUURHRXDUEBC-SXOMAYOGSA-N 0.000 abstract 1
- 238000007796 conventional method Methods 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 11
- 238000010586 diagram Methods 0.000 description 6
- 239000000758 substrate Substances 0.000 description 5
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 4
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 229910052732 germanium Inorganic materials 0.000 description 2
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000002230 thermal chemical vapour deposition Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Landscapes
- Photovoltaic Devices (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、非晶質半導体から
なるｉ層を備えた太陽電池や光センサ等の光起電力素子
の、光電変換特性を向上させる技術に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving the photoelectric conversion characteristics of a photovoltaic element such as a solar cell or a photosensor having an i-layer made of an amorphous semiconductor.
【０００２】[0002]
【従来の技術】非晶質シリコンに代表される非晶質半導
体は、その光吸収係数が大きく、また光に対する波長感
度が人間の視感度に近いことから、太陽電池や光センサ
等の光起電力素子に利用されている。そして、斯かる光
起電力素子にあっては、より長波長の光を有効に利用す
るために、非晶質シリコンよりも光学的バンドギャップ
の狭い非晶質シリコンゲルマニウムを利用することが検
討されている。2. Description of the Related Art An amorphous semiconductor typified by amorphous silicon has a large light absorption coefficient and a wavelength sensitivity to light close to human visibility, so that photovoltaic devices such as a solar cell and a photosensor are used. Used for power devices. In such a photovoltaic element, in order to effectively use light of a longer wavelength, the use of amorphous silicon germanium having a narrower optical band gap than amorphous silicon has been studied. ing.
【０００３】然し乍ら、斯かる非晶質シリコンゲルマニ
ウムにあっては、その光学的バンドギャップを小さくす
るためにゲルマニウムをシリコンに添加するため、この
添加量の増加に伴いに光電変換特性が次第に劣化すると
いう課題があった。However, in such amorphous silicon germanium, since germanium is added to silicon to reduce the optical band gap, the photoelectric conversion characteristics gradually deteriorate with the increase in the amount of addition. There was a problem that.
【０００４】そこで、斯かる課題を解決するために、例
えば特開昭６４−７１１８２号に開示された構造が検討
されている。Therefore, in order to solve such a problem, for example, a structure disclosed in Japanese Patent Application Laid-Open No. 64-71182 has been studied.
【０００５】図６はこの非晶質シリコンゲルマニウムを
用いた光起電力素子中で予測される光学的バンドギャッ
プの構造図を示し、図中ｐ，ｉ，ｎは、夫々ｐ型層，ｉ
型層及びｎ型層を表している。FIG. 6 shows a structural diagram of an optical band gap predicted in a photovoltaic device using this amorphous silicon germanium, where p, i, and n are a p-type layer and i, respectively.
1 illustrates a mold layer and an n-type layer.
【０００６】同図に示すように、この構造にあっては、
ｉ型層ｉが光学的バンドギャップの小さな第１部分ｉN
を有しており、そしてこの第１部分ｉNからｐ型層ｐ及
びｎ型層ｎへ向けて、光学的バンドギャップが次第に増
大する第２部分ｉW，ｉWを備えている。As shown in FIG. 1, in this structure,
i-type layer i is a first portion i N having a small optical band gap
And from the first portion i N to the p-type layer p and the n-type layer n, there are provided second portions i W , i W having gradually increasing optical band gaps.
【０００７】斯かる構造によれば、ｉ型層ｉ中に、該ｉ
層中で生成される電子・ホールの光生成キャリアを分離
する向きの電界が形成されるため、これらの光生成キャ
リアを有効に外部に取り出すことができることとなる。According to such a structure, in the i-type layer i,
Since an electric field is formed in such a direction as to separate photogenerated carriers of electrons and holes generated in the layer, these photogenerated carriers can be effectively extracted to the outside.
【０００８】[0008]
【発明が解決しようとする課題】然し乍ら、斯かる構造
を用いても、非晶質シリコンゲルマニウムを用いた太陽
電池の光電変換特性は、未だ十分なものではなかった。However, even with such a structure, the photoelectric conversion characteristics of a solar cell using amorphous silicon germanium have not been sufficient.
【０００９】[0009]
【課題を解決するための手段】斯かる課題を解決するた
めに、本発明光起電力素子は、非晶質半導体からなるｉ
型層と、該ｉ型層よりも光学的バンドギャップの広い不
純物層と、を備えてなる光起電力素子であって、前記不
純物層と前記ｉ型層との間に、前記不純物層からｉ型層
へ向けて、光学的バンドギャップが順次減少すると共に
前記不純物の導電型を決定する導電型決定不純物が順次
増加して含有せしめられたバッファ層を備えたことを特
徴としている。In order to solve such a problem, a photovoltaic device according to the present invention comprises an i-type photovoltaic device comprising an amorphous semiconductor.
A photovoltaic element comprising: a type layer; and an impurity layer having an optical bandgap wider than the i-type layer, wherein between the impurity layer and the i-type layer, i. The semiconductor device according to the present invention is characterized in that a buffer layer is provided in which the optical band gap is gradually reduced and the conductivity type determining impurities for determining the conductivity type of the impurities are sequentially increased toward the mold layer.
【００１０】また、前記ｉ型層が非晶質シリコンゲルマ
ニウムからなることを特徴としている。The i-type layer is made of amorphous silicon germanium.
【００１１】そして、前記不純物層がｐ型層であり、前
記バッファ層中におけるｐ型の導電型決定不純物の含有
量が、１×１０15ａｔｏｍｓ／ｃｍ3〜１×１０19ａｔ
ｏｍｓ／ｃｍ3の範囲であることを特徴としており、前
記バッファ層中における前記ｉ型層側の導電型決定不純
物の含有量が、前記ｐ型層側での含有量の数倍〜１００
倍程度であることを特徴としている。The impurity layer is a p-type layer, and the content of the p-type conductivity-determining impurity in the buffer layer is 1 × 10 15 atoms / cm 3 to 1 × 10 19 at.
oms / cm 3 , wherein the content of the impurity determining the conductivity type on the i-type layer side in the buffer layer is several times to 100 times the content on the p-type layer side.
It is characterized by being about twice as large.
【００１２】或いは、前記不純物層がｎ型層であり、前
記バッファ層中におけるｎ型の導電型決定不純物の含有
量が、１×１０15ａｔｏｍｓ／ｃｍ3〜１×１０19ａｔ
ｏｍｓ／ｃｍ3の範囲であることを特徴としており、前
記バッファ層中における前記ｉ型層側の導電型決定不純
物の含有量が、前記ｎ型層側での含有量の数倍〜１００
倍程度であることを特徴としている。Alternatively, the impurity layer is an n-type layer, and the content of the n-type conductivity-type determining impurity in the buffer layer is 1 × 10 15 atoms / cm 3 to 1 × 10 19 at.
oms / cm 3 , wherein the content of the conductivity type determining impurity on the i-type layer side in the buffer layer is several times to 100 times the content on the n-type layer side.
It is characterized by being about twice as large.
【００１３】[0013]
【実施の形態】本発明の光起電力素子に係わる第１実施
形態を図１を参照して説明する。図１は本実施形態に係
わる光起電力素子の素子構造断面図である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the photovoltaic element of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of the element structure of the photovoltaic element according to the present embodiment.
【００１４】図中、１はガラス、プラスチック等の透光
性且つ絶縁性を有する基板であり、２は該基板１上にス
パッタ法或いは熱ＣＶＤ法等の方法により形成されたＩ
ＴＯ，ＳｎＯ2等の透光性導電材からなる受光面電極膜
である。そして３ｐ，３ｂ，３ｉ及び３ｎは、夫々該受
光面電極膜２上にプラズマＣＶＤ法を用いて順次形成さ
れた、非晶質シリコンカーバイドからなるｐ型層３ｐ、
バッファ層３ｂ、非晶質シリコンゲルマニウムからなる
ｉ型層３ｉ及び非晶質シリコンからなるｎ型層３ｎであ
る。In FIG. 1, reference numeral 1 denotes a light-transmitting and insulating substrate such as glass or plastic, and reference numeral 2 denotes a substrate formed on the substrate 1 by a method such as a sputtering method or a thermal CVD method.
TO, a light-receiving surface electrode film made of a light-transmitting conductive material SnO 2 or the like. Reference numerals 3p, 3b, 3i, and 3n denote p-type layers 3p made of amorphous silicon carbide, which are sequentially formed on the light receiving surface electrode film 2 by using a plasma CVD method.
A buffer layer 3b, an i-type layer 3i made of amorphous silicon germanium, and an n-type layer 3n made of amorphous silicon.
【００１５】ここで、前記バッファ層３ｂは、その光学
的バンドギャップがｐ型層３ｐからｉ型層３ｉへ向かっ
て順次減少せしめられており、且つこの減少と対応する
ように、ｐ型の導電型決定不純物であるＢが順次増加し
て添加されている。Here, the buffer layer 3b has its optical band gap gradually reduced from the p-type layer 3p toward the i-type layer 3i, and a p-type conductive layer is formed so as to correspond to this decrease. B, which is a type-determining impurity, is added in increasing order.
【００１６】そして、４は前記ｎ型層３ｎ上に、スパッ
タ法或いは蒸着法等の方法により形成されたＡｇ，Ａｌ
等の金属膜からなる背面電極膜である。Reference numeral 4 denotes Ag, Al formed on the n-type layer 3n by a method such as sputtering or vapor deposition.
And a back electrode film made of a metal film.
【００１７】斯かる構成とすることで、本実施形態によ
れば、光照射によりｉ型層３ｉ中での電界強度の勾配を
従来よりも増大することができ、該層３ｉ中で発生した
電子・正孔の光生成キャリアを有効に外部に取り出すこ
とができるので、光電変換特性を向上することができ
る。With this configuration, according to the present embodiment, the gradient of the electric field strength in the i-type layer 3i can be increased by light irradiation as compared with the conventional case, and the electrons generated in the layer 3i can be increased. The photo-generated carriers of holes can be effectively extracted to the outside, so that the photoelectric conversion characteristics can be improved.
【００１８】表１に、斯かる太陽電池を構成する各非晶
質半導体層の形成条件を示す。ここで、形成方法には通
常のＲＦグロー放電によるプラズマＣＶＤ法を用いてい
る。Table 1 shows the conditions for forming each amorphous semiconductor layer constituting such a solar cell. Here, a plasma CVD method using ordinary RF glow discharge is used as a forming method.
【００１９】尚、比較例として、バッファ層３ｂに、Ｂ
を添加しないもの（比較例１）及びＢを層厚方向に均一
に添加したもの（比較例２）を形成した。As a comparative example, B was added to the buffer layer 3b.
No. was added (Comparative Example 1), and B was uniformly added in the layer thickness direction (Comparative Example 2).
【００２０】[0020]
【表１】 [Table 1]
【００２１】表１に示す通り、本実施形態においては、
まず基板１上に膜厚約１００Åの非晶質シリコンカーバ
イドからなるｐ型層３ｐを形成した後、該ｐ型層３ｐ上
に膜厚約２００Åの非晶質シリコンゲルマニウムからな
るバッファ層３ｂを形成している。この時、ＧｅＨ4ガ
スを０ｓｃｃｍから４０ｓｃｃｍまで漸次増加すること
で、該バッファ層３ｂの光学的バンドギャップを、前記
ｐ型層３ｐからｉ型層３ｉへ向けて順次減少せしめてい
る。尚、この時ＧｅＨ4ガスの増加に伴い同時にＨ2ガス
も増加することで、光学的バンドギャップの減少に伴う
膜特性の低下を抑制している。As shown in Table 1, in this embodiment,
First, a p-type layer 3p made of amorphous silicon carbide having a thickness of about 100 ° is formed on the substrate 1, and a buffer layer 3b made of amorphous silicon germanium having a thickness of about 200 ° is formed on the p-type layer 3p. doing. At this time, by gradually increasing the GeH 4 gas from 0 sccm to 40 sccm, the optical band gap of the buffer layer 3 b is gradually reduced from the p-type layer 3 p toward the i-type layer 3 i. At this time, the H 2 gas also increases at the same time as the GeH 4 gas increases, thereby suppressing the deterioration of the film characteristics due to the decrease in the optical band gap.
【００２２】そして、本実施形態にあっては、バッファ
層３ｂの形成時にＧｅＨ4ガスの増加に伴いＢ2Ｈ6ガス
も漸次増加することで、該層３ｂ中にｐ型の導電型決定
不純物であるボロン（Ｂ）を前記ｐ型層３ｐからｉ型層
３ｉへ向かって漸次増加するように含有せしめている。
ここで、ｐ型の導電型決定不純物はＢに限らずＡｌ，Ｇ
ａ等他の不純物を用いても良い。In the present embodiment, when the buffer layer 3b is formed, the B 2 H 6 gas also increases gradually with the increase of the GeH 4 gas, so that the p-type conductivity determining impurity is contained in the layer 3b. Is contained so as to gradually increase from the p-type layer 3p toward the i-type layer 3i.
Here, the p-type conductivity determining impurities are not limited to B, but Al, G
Other impurities such as a may be used.
【００２３】これに対し、比較例１ではバッファ層３ｂ
の形成時にＢ2Ｈ6ガスを一切導入せずに形成している。On the other hand, in Comparative Example 1, the buffer layer 3b
Is formed without introducing any B 2 H 6 gas.
【００２４】また、比較例２では、バッファ層３ｂの形
成時にＢ2Ｈ6ガスを一定量で導入し、該層３ｂの全体に
ｐ型の導電型決定不純物であるボロン（Ｂ）を均一に添
加している。In Comparative Example 2, a constant amount of B 2 H 6 gas was introduced during the formation of the buffer layer 3b, and boron (B), which is a p-type conductivity determining impurity, was uniformly distributed over the entire layer 3b. Has been added.
【００２５】そして、いずれの場合に於いてもこのバッ
ファ層３ｂ上に、膜厚約８００Åの非晶質シリコンゲル
マニウムからなるｉ型層３ｉ、及び膜厚約１００Åの非
晶質シリコンからなるｎ型層３ｎを形成した。In any case, on this buffer layer 3b, an i-type layer 3i of amorphous silicon germanium having a thickness of about 800 ° and an n-type layer 3 of amorphous silicon having a thickness of about 100 ° are formed. Layer 3n was formed.
【００２６】表２に、これらの太陽電池の光電変換特性
を示す。尚、測定は波長約６５０ｎｍ以下の光をカット
するＲ６５フィルタを使用して、波長約６５０ｎｍ以上
の光に対する光電変換特性を測定した。Table 2 shows the photoelectric conversion characteristics of these solar cells. The measurement was performed using an R65 filter that cuts light having a wavelength of about 650 nm or less, and the photoelectric conversion characteristics for light having a wavelength of about 650 nm or more were measured.
【００２７】[0027]
【表２】 [Table 2]
【００２８】表２から、本実施形態の光起電力素子は、
光電変換特性を表す重要なファクターである曲線因子
（Ｆ．Ｆ．）が他の素子に比べて向上し、最も高い光電
変換効率を有することがわかる。From Table 2, the photovoltaic device of this embodiment is
It can be seen that the fill factor (FF), which is an important factor representing the photoelectric conversion characteristics, is improved as compared with other elements and has the highest photoelectric conversion efficiency.
【００２９】以下に、本実施形態の光起電力素子により
最も高い光電変換効率が得られる理由について、詳細に
述べる 図２は、光起電力装置内において予測されるエネルギー
バンド図を示し、同図（Ａ）が従来の光起電力素子を、
（Ｂ）が本実施形態の光起電力素子を夫々表している。
また、同図においてＥVは価電子帯端を、ＥCは伝導帯端
を、そしてＥFはフェルミ位置を夫々表している。Hereinafter, the reason why the highest photoelectric conversion efficiency can be obtained by the photovoltaic device of this embodiment will be described in detail. FIG. 2 shows an energy band diagram predicted in the photovoltaic device. (A) is a conventional photovoltaic element,
(B) represents each of the photovoltaic elements of the present embodiment.
Moreover, the E V is the valence band edge in the figure, E C is the conduction band edge and E F, represents the Fermi position respectively.
【００３０】まず、図２（Ａ）に示した従来の光起電力
素子によれば、ｐ型層３ｐを構成する非晶質シリコンカ
ーバイドとｉ型層３ｉを構成する非晶質シリコンゲルマ
ニウムの光学的バンドギャップの差が大きいために、バ
ッファ層３ｂ中での電界強度の勾配が急峻である。そし
てバッファ層３ｂとｉ型層３ｉとの界面で電界強度の勾
配が急激に変化し、ｉ型層３ｉ中での勾配は緩やかにな
る。First, according to the conventional photovoltaic element shown in FIG. 2A, the optical characteristics of amorphous silicon carbide forming the p-type layer 3p and amorphous silicon germanium forming the i-type layer 3i are determined. Due to the large difference in the target band gap, the gradient of the electric field intensity in the buffer layer 3b is steep. Then, the gradient of the electric field intensity changes abruptly at the interface between the buffer layer 3b and the i-type layer 3i, and the gradient in the i-type layer 3i becomes gentle.
【００３１】従って、従来の光起電力素子に於いてはｉ
型層３ｉ中での電界強度の勾配が緩やかであるために、
光照射により該ｉ型層３ｉ中で生成された光キャリアが
電界により十分に分離されず、該層３ｉ中で再結合して
しまうため光電変換特性が低下していたのである。Therefore, in the conventional photovoltaic device, i
Since the gradient of the electric field strength in the mold layer 3i is gentle,
The photocarriers generated in the i-type layer 3i by the light irradiation were not sufficiently separated by the electric field and were recombined in the layer 3i, so that the photoelectric conversion characteristics were deteriorated.
【００３２】特にｉ型層３ｉが非晶質シリコンゲルマニ
ウムからなる場合にあっては、ゲルマニウムを添加する
ことにより生成される欠陥準位が多く、このためこの光
電変換特性の低下は一層顕著であった。In particular, when the i-type layer 3i is made of amorphous silicon germanium, the number of defect levels generated by adding germanium is large, so that the deterioration of the photoelectric conversion characteristics is more remarkable. Was.
【００３３】これに対し、図３（Ｂ）に示した本実施形
態の光起電力素子によれば、バッファ層３ｂにＢを添加
することで該層３ｂのフェルミ準位を価電子帯端Ｅｖに
近づけている。従って、従来バッファ層３ｂとｉ型層３
ｉとの界面に集中していた電界が緩和され、ｉ型層３ｉ
中での電界強度の勾配が増大することとなる。このた
め、ｉ型層３ｉ中で発生した光キャリアが再結合せずに
ｐ型層３ｐ或いはｎ型層３ｎに到達することができ、光
電変換特性が向上したものと考えられる。On the other hand, according to the photovoltaic device of this embodiment shown in FIG. 3B, by adding B to the buffer layer 3b, the Fermi level of the layer 3b is changed to the valence band edge Ev Approaching. Therefore, the conventional buffer layer 3b and the i-type layer 3
The electric field concentrated at the interface with i is reduced, and the i-type layer 3i
The gradient of the electric field intensity in the inside will increase. Therefore, it is considered that the photocarriers generated in the i-type layer 3i can reach the p-type layer 3p or the n-type layer 3n without recombination, and the photoelectric conversion characteristics are improved.
【００３４】このように、本実施形態の光起電力素子に
よれば、従来バッファ層３ｂとｉ型層３ｉとの界面に集
中していた電界を緩和することで、ｉ型層中での電界強
度の勾配を増大している。As described above, according to the photovoltaic element of the present embodiment, the electric field concentrated on the interface between the buffer layer 3b and the i-type layer 3i in the related art is reduced, so that the electric field in the i-type layer is reduced. The intensity gradient is increasing.
【００３５】さらに、Ｂの活性化率はａ−Ｓｉ中よりも
ａ−ＳｉＧｅ中の方が低く、しかもＧｅ量が多いほど活
性化率は低くなる。従って、バッファ層３ｂ中にＧｅが
層厚方向に順次増加して添加されている場合には、本実
施形態の如くＧｅ量の増加に対応してＢ量も順次増加し
て添加する必要がある。Further, the activation rate of B is lower in a-SiGe than in a-Si, and the activation rate decreases as the amount of Ge increases. Accordingly, when Ge is sequentially added to the buffer layer 3b in the layer thickness direction so as to increase, the B amount also needs to be sequentially increased and added in accordance with the increase in the Ge amount as in the present embodiment. .
【００３６】次に、図３に、バッファ層３ｂに添加する
Ｂの量を変化させて形成した種々の光起電力素子の光電
変換効率を示す。Next, FIG. 3 shows the photoelectric conversion efficiency of various photovoltaic elements formed by changing the amount of B added to the buffer layer 3b.
【００３７】ここで、Ｂの添加はバッファ層３ｂの層厚
方向に順次増加して行っており、図４の横軸はｐ層３ｐ
側、即ちＢの添加量が少ない領域でのＢ濃度を、縦軸は
ｉ層３ｉ側、即ちＢの添加量が多い領域でのＢ濃度を夫
々示している。そして、従来素子よりも高い光電変換効
率が得られた組み合わせを図中に丸印で表した。Here, the addition of B is performed in such a manner that it is sequentially increased in the thickness direction of the buffer layer 3b, and the horizontal axis in FIG.
The ordinate indicates the B concentration in the region where the amount of B added is small, and the ordinate indicates the B concentration in the i layer 3i side, that is, the region where the amount of B added is large. And the combination which obtained the photoelectric conversion efficiency higher than the conventional element was shown by the circle in the figure.
【００３８】図３から、Ｂ濃度を１０15ａｔｏｍｓ／ｃ
ｍ3〜１０19ａｔｏｍｓ／ｃｍ3の範囲とすることで、従
来よりも高い光電変換効率を得られることがわかる。From FIG. 3, it is found that the B concentration is 10 15 atoms / c.
It can be seen that by setting the range of m 3 to 10 19 atoms / cm 3, a higher photoelectric conversion efficiency than that of the related art can be obtained.
【００３９】特に、ｐ層３ｐ側におけるＢ濃度を１０15
ａｔｏｍｓ／ｃｍ3〜１０18ａｔｏｍｓ／ｃｍ3の範囲と
し、ｉ層３ｉ側におけるＢ濃度をｐ層３ｐ側でのそれの
数倍〜１００倍程度とした範囲で従来よりも高い光電変
換効率が得られている。In particular, the B concentration on the p layer 3p side is set to 10 15
In the range of atoms / cm 3 to 10 18 atoms / cm 3 and the B concentration on the i-layer 3i side which is several times to 100 times that on the p-layer 3p side, higher photoelectric conversion efficiency than before can be obtained. Have been.
【００４０】次に、本発明光起電力素子の第２実施形態
について図４を参照して説明する。図４は本実施形態に
係わる太陽電池の素子構造断面図である。尚図１に示し
た第１実施形態の光起電力素子と同一の部分には同一の
符号を付している。Next, a second embodiment of the photovoltaic element of the present invention will be described with reference to FIG. FIG. 4 is a sectional view of the element structure of the solar cell according to the present embodiment. The same parts as those of the photovoltaic element of the first embodiment shown in FIG. 1 are denoted by the same reference numerals.
【００４１】同図において、図１に示した第１実施形態
の光起電力素子と異なる点は、ｉ型層３ｉと、ｎ型層３
ｎとの間に第２のバッファ層３ｂ’を設けた点にある。In the figure, the difference from the photovoltaic element of the first embodiment shown in FIG. 1 is that the i-type layer 3i and the n-type layer 3
This is the point that the second buffer layer 3b 'is provided between the second buffer layer 3b' and n.
【００４２】そして、このバッファ層３ｂ’の光学的バ
ンドギャップは前記ｎ型層３ｎからｉ型層３ｉへ向かっ
て順次減少せしめられており、且つｎ型の導電型決定不
純物であるリン（Ｐ）が、前記光学的バンドギャップの
減少に対応して増加すべく含有せしめられている。尚、
ｎ型の導電型決定不純物としては、Ｐに限らずＡｓ，Ｓ
ｂ或いはＯ、Ｎ等の他の不純物を用いることもできる。The optical band gap of the buffer layer 3b 'is gradually reduced from the n-type layer 3n toward the i-type layer 3i, and phosphorus (P) which is an n-type conductivity determining impurity is used. Is included to increase in response to the decrease in the optical band gap. still,
The n-type conductivity determining impurities are not limited to P, but include As, S
Another impurity such as b or O or N may be used.
【００４３】斯かる構成によれば、前述した実施形態１
の場合と同じ理由で、ｉ型層３ｉとｎ型層３ｎとの界面
に集中していた電界を緩和してｉ型層３ｉ中での電界強
度の勾配をさらに増大でき、ｉ型層３ｉ中で生成された
光生成キャリアをより外部に有効に取り出すことがで
き、光電変換特性を向上することができる。According to such a configuration, the first embodiment described above
For the same reason as in the above case, the electric field concentrated at the interface between the i-type layer 3i and the n-type layer 3n can be alleviated to further increase the gradient of the electric field intensity in the i-type layer 3i. The photo-generated carriers generated in step (1) can be more effectively extracted to the outside, and the photoelectric conversion characteristics can be improved.
【００４４】表３に、斯かる太陽電池を構成する各非晶
質半導体層の形成条件を示す。ここで、形成方法として
は通常のＲＦグロー放電によるプラズマＣＶＤ法を用い
ている。Table 3 shows the conditions for forming each amorphous semiconductor layer constituting such a solar cell. Here, a plasma CVD method using ordinary RF glow discharge is used as a forming method.
【００４５】尚、比較例、バッファ層３ｂ’にＰを添加
しないもの（比較例３）及びバッファ層３ｂ’の全体に
Ｐを均一に添加したもの（比較例４）もあわせて形成し
た。Incidentally, the comparative example, the one in which P was not added to the buffer layer 3b '(Comparative Example 3), and the one in which P was uniformly added to the entire buffer layer 3b' (Comparative Example 4) were also formed.
【００４６】[0046]
【表３】 [Table 3]
【００４７】本実施形態に於いては、表３に示す通り、
ｉ型層３ｉまでは前述した実施形態１と同様にして形成
している。そして、ｉ型層３ｉ上に、膜厚約２００Åの
非晶質シリコンゲルマニウムからなるバッファ層３ｂ’
を形成する。この時、ＧｅＨ 4ガスを４０ｓｃｃｍから
０ｓｃｃｍまで漸次減少することで、該バッファ層３
ｂ’の光学的バンドギャップを、前記ｉ型層３ｉからｎ
型層３ｎへ向けて順次増大せしめている。尚、この時Ｇ
ｅＨ4ガスの減少に伴いＨ2ガスも減少せしめている。In the present embodiment, as shown in Table 3,
Formed up to the i-type layer 3i in the same manner as in the first embodiment.
doing. Then, on the i-type layer 3i, a film having a thickness of about 200 ° is formed.
Buffer layer 3b 'made of amorphous silicon germanium
To form At this time, GeH FourGas from 40sccm
The buffer layer 3 gradually decreases to 0 sccm.
The optical band gap of b ′ is changed from the i-type layer 3i to n.
It gradually increases toward the mold layer 3n. At this time, G
eHFourAs the gas decreases, HTwoGas is also decreasing.
【００４８】そして、本実施形態にあっては、バッファ
層３ｂ’の形成時に、ＧｅＨ4ガスの減少に伴いＰＨ3ガ
スも漸次減少することで、該層３ｂ’中にリン（Ｐ）を
前記ｉ型層３ｉからｎ型層３ｎへ向かって漸次減少する
ように含有せしめている。In the present embodiment, when the buffer layer 3b 'is formed, the PH 3 gas also decreases gradually as the GeH 4 gas decreases, so that phosphorus (P) is contained in the layer 3b'. It is contained so as to gradually decrease from the i-type layer 3i toward the n-type layer 3n.
【００４９】また、比較例３にあっては、バッファ層３
ｂ’の形成時にＰＨ3を導入することなく形成してお
り、比較例４にあっては、バッファ層３ｂ’の形成時に
ＰＨ3ガスを一定量で導入し、該層３ｂ’の全体にＰを
均一に含有せしめている。In Comparative Example 3, the buffer layer 3
b 'is formed without introducing PH 3. In Comparative Example 4, a constant amount of PH 3 gas is introduced at the time of forming the buffer layer 3 b ′, and P 3 is introduced into the entire layer 3 b ′. Is uniformly contained.
【００５０】そして、いずれの実施例に於いてもこのバ
ッファ層３ｂ’上に、膜厚約１００Åの非晶質シリコン
からなるｎ型層３ｎを形成した。In each embodiment, an n-type layer 3n made of amorphous silicon having a thickness of about 100 ° was formed on the buffer layer 3b '.
【００５１】表４に、本実施形態と比較例の光起電力素
子の光電変換特性を示す。尚測定は前述の場合と同様
に、波長約６５０ｎｍ以下の光をカットするＲ６５フィ
ルタを使用して、波長約６５０ｎｍ以上の光に対する光
電変換特性を測定した。Table 4 shows the photoelectric conversion characteristics of the photovoltaic devices of the present embodiment and the comparative example. In the measurement, as in the case described above, the photoelectric conversion characteristics with respect to light having a wavelength of about 650 nm or more were measured using an R65 filter that cuts light having a wavelength of about 650 nm or less.
【００５２】[0052]
【表４】 [Table 4]
【００５３】表４から、本実施形態による光起電力素子
が、他の素子に比べ曲線因子（Ｆ．Ｆ．）が向上し、最
も高い光電変換効率を有することがわかる。From Table 4, it can be seen that the photovoltaic device according to the present embodiment has an improved fill factor (FF) as compared with the other devices and has the highest photoelectric conversion efficiency.
【００５４】次に、図５に、バッファ層３ｂ’に添加す
るＰの量を変化させて形成した種々の光起電力素子の光
電変換効率を示す。Next, FIG. 5 shows the photoelectric conversion efficiencies of various photovoltaic elements formed by changing the amount of P added to the buffer layer 3b '.
【００５５】ここで、Ｐの添加はバッファ層３ｂ’の層
厚方向に順次減少して行っており、同図の縦軸はｉ型層
３ｉ側、即ちＰの添加量が多い領域でのＰ濃度を、横軸
はｎ層３ｎ側、即ちＰの添加量が少ない領域でのＰ濃度
を夫々示している。そして、従来装置よりも高い光電変
換効率が得られた組み合わせを図中に丸印で表した。Here, the addition of P is performed in such a manner that the addition of P is gradually decreased in the thickness direction of the buffer layer 3b ', and the vertical axis in the figure indicates the P side on the i-type layer 3i side, that is, the region where the amount of P added is large. The abscissa indicates the P concentration on the n-layer 3n side, that is, in the region where the amount of P added is small. And the combination which obtained the photoelectric conversion efficiency higher than the conventional apparatus was shown by the circle in the figure.
【００５６】同図から、Ｐ濃度を１０15ａｔｏｍｓ／ｃ
ｍ3〜１０19ａｔｏｍｓ／ｃｍ3の範囲とすることで、従
来よりも高い光電変換効率を得られることがわかる。From the figure, it is found that the P concentration is 10 15 atoms / c.
It can be seen that by setting the range of m 3 to 10 19 atoms / cm 3, a higher photoelectric conversion efficiency than that of the related art can be obtained.
【００５７】特に、ｎ層３ｎ側におけるＰ濃度が１０15
ａｔｏｍｓ／ｃｍ3〜１０18ａｔｏｍｓ／ｃｍ3の範囲と
し、ｉ層３ｉ側におけるＰ濃度をｎ層３ｐ側でのそれの
数倍〜１００倍程度とした範囲で従来よりも高い光電変
換効率が得られている。In particular, the P concentration on the n-layer 3n side is 10 15
In the range of atoms / cm 3 to 10 18 atoms / cm 3 and the P concentration on the i-layer 3i side several times to 100 times higher than that on the n-layer 3p side, higher photoelectric conversion efficiency than before can be obtained. Have been.
【００５８】尚、以上の実施形態に於いてはｉ型層３ｉ
を非晶質シリコンゲルマニウムから構成した光起電力素
子について説明したが、これに限らず本発明は、ｉ型層
３ｉを非晶質シリコン或いは非晶質シリコンカーバイド
等の他の非晶質半導体から構成された光起電力素子につ
いても適用することができる。In the above embodiment, the i-type layer 3i
Has been described with respect to a photovoltaic element composed of amorphous silicon germanium. However, the present invention is not limited to this, and the present invention provides that the i-type layer 3i is made of amorphous silicon or another amorphous semiconductor such as amorphous silicon carbide. The present invention can also be applied to a configured photovoltaic element.
【００５９】[0059]
【発明の効果】以上のように、本発明によれば、ｉ型層
３ｉ中での電界強度の勾配を従来よりも急峻なものとで
きるため、該層３ｉ中での光生成キャリアの再結合を抑
制でき、良好な光電変換効率を有する光起電力素子を提
供することができる。As described above, according to the present invention, the gradient of the electric field intensity in the i-type layer 3i can be made steeper than in the prior art, so that the recombination of photogenerated carriers in the layer 3i can be achieved. Can be suppressed, and a photovoltaic element having good photoelectric conversion efficiency can be provided.
【図１】本発明の第１実施形態に係わる光起電力素子の
素子構造断面図である。FIG. 1 is a sectional view of an element structure of a photovoltaic element according to a first embodiment of the present invention.
【図２】第１実施形態の光起電力素子中で予測されるエ
ネルギーバンドの予測図である。FIG. 2 is a prediction diagram of an energy band predicted in the photovoltaic device of the first embodiment.
【図３】バッファ層へのＢの添加量と、光電変換特性と
の関係を表す特性図である。FIG. 3 is a characteristic diagram showing a relationship between an amount of B added to a buffer layer and photoelectric conversion characteristics.
【図４】本発明の第２実施形態にかかんある光起電力素
子の素子構造断面図である。FIG. 4 is a sectional view of a photovoltaic device according to a second embodiment of the present invention;
【図５】第２のバッファ層へのＰの添加量と、光電変換
特性との関係を示す特性図である。FIG. 5 is a characteristic diagram showing a relationship between an amount of P added to a second buffer layer and photoelectric conversion characteristics.
【図６】従来の光起電力素子において予測される光学的
バンドギャップの構造図である。FIG. 6 is a structural diagram of an optical band gap predicted in a conventional photovoltaic device.
１…基板、２…受光面電極膜、３ｐ…ｐ型層、３ｉ…ｉ
型層、３ｎ…ｎ型層 ３ｂ，３ｂ’…バッファ層DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Light receiving surface electrode film, 3p ... p-type layer, 3i ... i
Mold layer, 3n ... n-type layer 3b, 3b '... buffer layer
Claims (6)
層よりも光学的バンドギャップの広い不純物層と、を備
えてなる光起電力素子であって、 前記不純物層と前記ｉ型層との間に、前記不純物層から
ｉ型層へ向けて、光学的バンドギャップが順次減少する
と共に前記不純物の導電型を決定する導電型決定不純物
が順次増加して含有せしめられたバッファ層を備えたこ
とを特徴とする光起電力素子。1. A photovoltaic device comprising: an i-type layer made of an amorphous semiconductor; and an impurity layer having an optical bandgap wider than the i-type layer. A buffer layer containing, between the impurity layer and the i-type layer, an optical band gap that is gradually reduced and a conductivity type determining impurity that determines the conductivity type of the impurity is sequentially increased. A photovoltaic element comprising:
ムからなることを特徴とする請求項１記載の光起電力素
子。2. The photovoltaic device according to claim 1, wherein said i-type layer is made of amorphous silicon germanium.
ファ層中におけるｐ型の導電型決定不純物の含有量が、
１×１０15ａｔｏｍｓ／ｃｍ3〜１×１０19ａｔｏｍｓ
／ｃｍ3の範囲であることを特徴とする請求項１もしく
は２記載の光起電力素子。3. The semiconductor device according to claim 1, wherein the impurity layer is a p-type layer, and the content of the p-type conductivity determining impurity in the buffer layer is:
1 × 10 15 atoms / cm 3 to 1 × 10 19 atoms
3. The photovoltaic device according to claim 1, wherein the photovoltaic device has a range of / cm 3 .
の導電型決定不純物の含有量が、前記ｐ型層側での含有
量の数倍〜１００倍程度であることを特徴とする請求項
３記載の光起電力素子。4. The method according to claim 1, wherein the content of the impurity determining the conductivity type on the i-type layer side in the buffer layer is about several times to about 100 times the content on the p-type layer side. 3. The photovoltaic element according to 3.
ファ層中におけるｎ型の導電型決定不純物の含有量が、
１×１０15ａｔｏｍｓ／ｃｍ3〜１×１０19ａｔｏｍｓ
／ｃｍ3の範囲であることを特徴とする請求項１もしく
は２記載の光起電力素子。5. The semiconductor device according to claim 1, wherein the impurity layer is an n-type layer, and the content of the n-type conductivity-type determining impurity in the buffer layer is:
1 × 10 15 atoms / cm 3 to 1 × 10 19 atoms
3. The photovoltaic device according to claim 1, wherein the photovoltaic device has a range of / cm 3 .
の導電型決定不純物の含有量が、前記ｎ型層側での含有
量の数倍〜１００倍程度であることを特徴とする請求項
５記載の光起電力素子。6. The semiconductor device according to claim 1, wherein the content of the impurity determining the conductivity type on the i-type layer side in the buffer layer is about several to 100 times the content on the n-type layer side. 6. The photovoltaic element according to 5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16600596A JP3291435B2 (en) | 1996-06-26 | 1996-06-26 | Photovoltaic element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16600596A JP3291435B2 (en) | 1996-06-26 | 1996-06-26 | Photovoltaic element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1012902A true JPH1012902A (en) | 1998-01-16 |
| JP3291435B2 JP3291435B2 (en) | 2002-06-10 |
Family
ID=15823126
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16600596A Expired - Fee Related JP3291435B2 (en) | 1996-06-26 | 1996-06-26 | Photovoltaic element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3291435B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006210558A (en) * | 2005-01-27 | 2006-08-10 | Toppan Printing Co Ltd | Non-single-crystal solar battery, manufacturing method thereof, and non-single-crystal solar battery manufacturing apparatus |
-
1996
- 1996-06-26 JP JP16600596A patent/JP3291435B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006210558A (en) * | 2005-01-27 | 2006-08-10 | Toppan Printing Co Ltd | Non-single-crystal solar battery, manufacturing method thereof, and non-single-crystal solar battery manufacturing apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3291435B2 (en) | 2002-06-10 |
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