JPH0438147B2

JPH0438147B2 -

Info

Publication number: JPH0438147B2
Application number: JP59031140A
Authority: JP
Inventors: Hirotsugu Nagayama; Masato Hyodo; Masao Misonoo; Hisao Pponda; Hideo Kawahara
Original assignee: Nippon Sheet Glass Co Ltd
Current assignee: Nippon Sheet Glass Co Ltd
Priority date: 1984-02-21
Filing date: 1984-02-21
Publication date: 1992-06-23
Also published as: JPS60175465A

Description

[Detailed description of the invention]

ａ産業上の利用分野本発明は太陽電池基板に関し、特に光電変換効
率の良好な太陽電池基板に関する。ｂ従来技術近年シランガスをグロー放電分解することなど
により作製される非晶質シリコン（ａ−si）を用
いた太陽電池が低コストで製造可能な光電変換装
置の一つとして注目を浴びている。しかしかかる
ａ−si太陽電池においては、その光電変換効率が
他の結晶半導体（結晶Si、GaAsなど）に比べ極
めて低いことが問題となり、これを解決するため
作製方法や電池の構造に対し種々の対策が考案さ
れている。特に電池の表面における光反射損失を
低減し短絡電流を増大させることは重要であり、
このため太陽電池を凹凸構造にして、入射光を電
池内で多重反射屈折させることにより長波長光に
対する収集効率を向上させることが考えられてい
る。しかしながら凹凸の度合いが大き過ぎるとピ
ンホール等の欠陥が発生したり膜厚が不均一にな
りやすく、かえつて太陽電池の特性（特に開放電
圧・良品率）が低下する。従つてこの様な凹凸構
造を有する太陽電池においては、凹凸の程度を最
適化する必要があつた。ｃ発明の目的本発明の目的は、太陽光の収集効率の高い太陽
電池基板を提供することであり、さらに詳しくは
開放電圧および良品率の高い凹凸形状被膜を有す
る太陽電池が得られる太陽電池基板を提供するこ
とである。ｄ発明の構成本発明は、ヘイズ率が１％以上であり、直径
300〜5000Å、高さ200〜3000Åの多数の凸部を持
つた酸化珪素被膜を有することを特徴とする太陽
電池基板である。ここで本発明の酸化珪素被膜のヘイズ率は航空
機用メタクリル樹脂板の曇価測定法（JIS、Ｋ−
6714（1977））により測定して１％以上であるが、
ヘイズ率１％より小さな酸化珪素被膜では上述の
様な多重反射屈折による太陽電池の効率の向上が
あまり得られないため好ましくない。又本発明の
酸化珪素被膜の有する凹凸形状は、直径300〜
5000Å、高さ200〜3000Åの略おわん状の凹凸形
状である。直径300Åより小さいもの、高さ200Å
より低いものでは高いヘイズ率を実現するため
に、数多い凹凸を必要とし、数多い凹凸形状を形
成することは、生産性が悪くなることが多いので
好ましくない。又直径5000Åより大きなもの、高
さ3000Åより高いものではその上に順次積層する
ａ−SiのＰ層（膜厚約150Å）に亀裂を生じやす
くなるなどの欠点となるため好ましくない。凹凸
の形状は、上部からの圧力などによつて上記ａ−
Si層に亀裂等が生じにくい略おわん状の凹凸が好
まれる。ここで太陽電池基板として使用出来る基板材料
としては、酸化珪素を含むガラス、セラミツク
ス、プラスチツク等の透明材料があげられる。基
板の厚みは基板材がガラスの場合0.3〜８mmが好
まれ、特に1.1〜3.0mmが好ましい。プラスチツク
材の場合フイルム状から５mm厚程度の板厚を持つ
た状態まで使用出来る。ここで基板の厚みは光の
透過率の極端な低下が起こらず、又太陽電池とし
ての強度の得られる厚みであればどの様な厚みで
あつても良い。ここで、上記凹凸形状を有する酸化珪素被膜の
形成には、例えば珪弗化水素酸の酸化珪素飽和水
溶液にホウ酸を添加して酸化珪素のかたまりが浮
遊している状態にした処理液中に、処理液が浸漬
した基材表面で0.2〜8.0cm／minの速度で流動す
る状態で基材を浸漬し、基材表面に凹凸形状を有
する酸化珪素被膜を折出させる方法が利用出来
る。上記透明基材を上記方法で処理することによ
り、直径300〜5000Å、高さ200〜3000Åの略おわ
ん状の凹凸形状を持つた酸化珪素被膜が実現され
る。又、本発明の酸化珪素被膜は、上記透明基材を
上記方法で処理し、その後さらにその上に酸化珪
素被膜を均一な厚みで作成する事によつても得ら
れる。２層目の均一な厚みを有する酸化珪素被膜の作
成には通常の酸化珪素被膜の製造方法が使用出来
る。具体的には、(1)有機シリコン化合物をコーテ
イングした後に400〜500℃に加熱してSiO₂焼成
膜を得る方法(2)スパツタ法(3)CVD法(4)珪弗化水
素酸の酸化珪素飽和水溶液にホウ酸を添加させ
SiO₂膜を析出させる方法（特開昭57−196744）
などが挙げられる。酸化珪素被膜を２層構造とする事は、第１層の
凹凸形状の急傾斜を有する部分を平滑化して、上
部に積層するａ−Si層に亀裂等が発生するのを防
止するため、得られる太陽電池の欠点が少なくな
り、好ましい。ここで第２層を形成する時の好ま
しい厚みは50〜2000Åである。50Åよりうすい厚
みでは上記第２層の効果が十分でなく、又2000Å
より厚いと第１層の凹凸形状がつぶされる事とな
るので好ましくない。特に1000Å前後の膜厚が望
ましい。又第２層の形成は第１層により得られる
ヘイズ率の低下を導くために、酸化珪素被膜を２
層の構造とする時には第１層目においてヘイズ率
が2.5％以上であることが望ましい。第１層のヘ
イズ率が2.5％より少ないと２層目の被覆により
ヘイズ率が小さくなりすぎて凹凸形状の効果が小
さくなり好ましくない。以下に本発明を実施例に基き説明する。ｅ実施例実施例１大きさが100（mm）×100（mm）の厚味１（mm）のソ
ーダライムガラスを0.5％濃度（重量％）のHF水
溶液中に10分間浸漬した後、十分に洗浄し乾燥し
試料ガラスとした。次に試料を浸漬するための浸
漬槽を用意する。浸漬槽は外槽１と内槽２から成り、内槽と外槽
の間には水３が満してある。実験では、この水の
温度が35℃となるよう、水はヒーター４で加熱さ
れ、かつ温度分布均一化のため撹拌器５で撹拌さ
れている。内槽は前部６、中部７、後部８から成
り、その各部には２モル／の珪弗化水素酸に酸
化珪素を飽和し、しかる後水で１モル／に希釈
した３の処理液が満たしてある。内槽後部８の
処理液は循環ポンプ１０により内槽前部６へ戻さ
れる。ここで全処理液量に対する１分間当りの処
理液循環量の割合は８％に設定した。（ここで全
処理液量は約３であり、処理槽中部の底面積は
約150cm²であるので、浸漬する基材ガラス表面で
の液流速は約1.6cm／minと予想される。）この反応液に0.5モル／の濃度のホウ酸水溶
液１１を0.2ml／分で連続的に滴下し、10時間保
持した。その後この反応液に試料９を内槽中央部７に垂
直状に浸漬・保持する。反応処理液の循環および
ホウ酸水溶液の添加を続けながら４時間保持し、
その後試料を取り出し洗浄乾燥した。得られた被膜の厚みは約1000Åであり、同被膜
の電子顕微鏡観察の結果直径300〜5000Å、高さ
200〜3000Åの略おわん形をした多数の凹凸が見
られた。約10700倍の倍率の電子顕微鏡写真を第
２図に示す。凹凸の形状、および単位面積あたりの数はその
総合効果として、入射光に対する散乱度合（ヘイ
ズ率）として表わすことが出来る。ここで、得ら
れた表裏両面に凹凸形状を持つた上記試料のヘイ
ズ率は２％であり、試料の両面に凹凸のない
SiO₂膜をコートした試料のヘイズ率0.2％とくら
べると大きな値であつた。ここでヘイズ率の測定
は航空機用メタクリル樹脂板の曇価測定法（JIS、
Ｋ−6714（1977））により測定した。実施例２処理液の循環量を全処理液量に対し１分間当り
３％（処理液の流速約0.6cm／min）となる様に
変更し、試料の浸漬時間を３時間に変更した以外
は実施例１と同様の方法により試料上に約1000Å
の厚さの酸化珪素被膜を形成した。得られた酸化珪素被膜は厚み約1000Åの膜であ
り、試料の電子顕微鏡観察により試料には実施例
１と同様の直径300〜5000Å、高さ200〜3000Åの
略おわん形をした多数の凹凸が存在することが確
認された。又得られた試料両面に凹凸形状を持つた上記試
料のヘイズ率は７％であり、実施例２により得ら
れた試料は実施例１により得られた試料より深い
弧を持つ凹凸の割合または凹凸の数が増加してい
ることが予想される。実施例３実施例２によつて製造された凹凸形状を有する
酸化珪素被膜つき基板ガラス（以後A0と呼ぶ）
をリン入り酸化珪素形成液（東京応化工業社製
OCD溶液）に浸漬し、その後500℃で焼成を行な
い膜厚約1000Åの酸化珪素被膜を試料両面に形成
した。（以後この基板をA1と呼ぶ）ヘイズ率は７
％から３％へと変化した。又同様にA0のガラス基板上にスパツタ法によ
り約200Åの膜厚の酸化珪素被膜を試料片面に形
成した。（以後この基板をA2と呼ぶ）ヘイズ率は
７％から６％へ変化した。又別に実施例２と同様なガラス基板を珪弗化水
素酸の酸化珪素飽和水溶液にホウ酸を添加した処
理液に浸漬し平滑度の高い酸化珪素被膜約1000Å
を作成した比較用基板Ｂを作成した。（特願昭58
−137217）これらA0、A1、２層構造側のA2基板、Ｂ基板
を用いてアモルフアスSiの太陽電池を作成した。
作成手順を以下に示す。基板A0、A1、A2、Ｂ上にモノブチル錫トリク
ロライドの蒸気及びドーパントとしてCH₃CHF₂
ガスを用いCVD法によつて2000Åの酸化錫透明
導電膜を形成した。次いでモノシラン（SiH₄）
ガスを主成分とする原料ガスを用いて100Pa程度
の圧力下で容量結合型高周波グロー放電装置によ
り、 (1) Ｐ型半導体層（ホウ素ドープのａ−SiC：
Ｈ、約150Å厚） (2) 真性半導体層（ａ−Si：Ｈ、約5000Å厚） (3) ｎ型半導体層（リンドープのマイクロクリス
タリンSi（μc−Si）：Ｈ、約300Å厚）をそれぞれ順番に推積させ、最後にAl電極（約
500Å）を真空中（約10^-4Pa）で蒸着法により作
成した。上記Al電極を作成する際基板上に直径２mmの
穴があいたマスクをのせておき、直径２mmの太陽
電池を20ケ作成した。得られた太陽電池にAM1の100ｍＷ／cm²の光を
照射し、負荷を無限大とした時の起電力（開放電
圧；Ｖ）および負荷を０とした時の太陽電池単位
表面積あたりの電流値（短絡電流；ｍＡ／cm²）お
よび正常な特性を示す太陽電池の割合（生存率；
％）を測定した。第１表に得られた測定結果を示す。表より明ら
かな様に凹凸形状を持つ酸化珪素被膜を用いた基
板A0、A1、A2が平滑な酸化珪素被膜を用いた基
板Ｂよりも大きな短絡電流値を示していることが
わかる。又、酸化珪素被膜を２層の構造とするこ
とにより、太陽電池を作成した時により性能が高
く（開放電圧低下の度合が少ない）、より生存率
の高い太陽電池基板が提供されていることがわか
る。ここで上記実施例では基材として酸化珪素を含
むガラスを用い、又形状も100mm×100mmとし、処
理工程も断続的に行なつたが、前記酸化珪素被膜
は付着被膜であるのでその他のガラス板、プラス
チツク板、セラミツクス板などあらゆる材料を使
用することができる。又形状も100mm×100mmに限
らず大型化出来、又処理工程も酸化珪素の飽和 a. Industrial Application Field The present invention relates to a solar cell substrate, and particularly to a solar cell substrate with good photoelectric conversion efficiency. B. Prior Art In recent years, solar cells using amorphous silicon (A-SI), which are manufactured by glow discharge decomposition of silane gas, have been attracting attention as one of the photoelectric conversion devices that can be manufactured at low cost. However, the problem with such A-SI solar cells is that their photoelectric conversion efficiency is extremely low compared to other crystalline semiconductors (crystalline Si, GaAs, etc.), and to solve this problem, various changes have been made to the manufacturing method and cell structure. Countermeasures have been devised. In particular, it is important to reduce light reflection loss on the surface of the battery and increase short-circuit current.
For this reason, it has been considered to improve the collection efficiency for long wavelength light by making the solar cell have an uneven structure so that the incident light is subjected to multiple reflection and refraction within the cell. However, if the degree of unevenness is too large, defects such as pinholes may occur or the film thickness may become uneven, which may actually reduce the characteristics of the solar cell (particularly the open circuit voltage and yield rate). Therefore, in a solar cell having such an uneven structure, it is necessary to optimize the degree of unevenness. c. Purpose of the Invention The purpose of the present invention is to provide a solar cell substrate with high sunlight collection efficiency, and more specifically, a solar cell substrate from which a solar cell having a concavo-convex shaped coating with high open-circuit voltage and high yield rate can be obtained. The goal is to provide the following. d Structure of the invention The present invention has a haze rate of 1% or more and a diameter of
This is a solar cell substrate characterized by having a silicon oxide film having a large number of convex portions with a diameter of 300 to 5000 Å and a height of 200 to 3000 Å. Here, the haze rate of the silicon oxide film of the present invention is determined by the haze value measurement method (JIS, K-
6714 (1977)) is 1% or more, but
A silicon oxide film having a haze ratio of less than 1% is not preferable because the efficiency of the solar cell cannot be improved much due to multiple reflection/refraction as described above. Moreover, the uneven shape of the silicon oxide film of the present invention has a diameter of 300~
It has a roughly bowl-shaped uneven shape with a thickness of 5000 Å and a height of 200 to 3000 Å. Diameter smaller than 300Å, height 200Å
If the haze ratio is lower, a large number of irregularities are required in order to achieve a high haze ratio, and forming a large number of irregularities is not preferable because productivity often deteriorates. Moreover, a diameter of more than 5000 Å and a height of more than 3000 Å are undesirable because they tend to cause cracks in the a-Si P layer (about 150 Å thick) successively laminated thereon. The shape of the unevenness is determined by pressure from above, etc.
Approximately bowl-shaped irregularities that are less likely to cause cracks in the Si layer are preferred. Examples of substrate materials that can be used as the solar cell substrate include transparent materials such as glass, ceramics, and plastics containing silicon oxide. When the substrate material is glass, the thickness of the substrate is preferably 0.3 to 8 mm, particularly preferably 1.1 to 3.0 mm. In the case of plastic materials, it can be used in anything from a film to a plate with a thickness of about 5 mm. Here, the thickness of the substrate may be any thickness as long as it does not cause an extreme decrease in light transmittance and provides sufficient strength as a solar cell. Here, to form the silicon oxide film having the above-mentioned uneven shape, for example, boric acid is added to a silicon oxide saturated aqueous solution of hydrosilicofluoric acid to create a state in which silicon oxide lumps are suspended. A method can be used in which the substrate is immersed in a state in which a treatment liquid flows at a rate of 0.2 to 8.0 cm/min on the surface of the substrate, and a silicon oxide film having an uneven shape is deposited on the surface of the substrate. By treating the transparent base material with the above method, a silicon oxide film having an approximately bowl-shaped uneven shape with a diameter of 300 to 5000 Å and a height of 200 to 3000 Å is realized. The silicon oxide film of the present invention can also be obtained by treating the above-mentioned transparent substrate with the above-described method, and then further forming a silicon oxide film with a uniform thickness thereon. A normal silicon oxide film manufacturing method can be used to create the second layer of silicon oxide film having a uniform thickness. Specifically, (1) a method of coating an organic silicon compound and then heating it to 400 to 500°C to obtain a fired SiO ₂ film, (2) a sputtering method, (3) a CVD method, and (4) an oxidation of hydrosilicofluoric acid. Adding boric acid to a silicon saturated aqueous solution
Method for depositing SiO ₂ film (Japanese Patent Application Laid-Open No. 57-196744)
Examples include. The two-layer structure of the silicon oxide film is advantageous because it smooths out the steeply sloped parts of the first layer and prevents cracks from forming in the a-Si layer stacked on top. This is preferable because it reduces the drawbacks of solar cells. Here, the preferred thickness when forming the second layer is 50 to 2000 Å. If the thickness is thinner than 50 Å, the effect of the second layer will not be sufficient, and if the thickness is thinner than 50 Å,
If it is thicker, the uneven shape of the first layer will be crushed, which is not preferable. In particular, a film thickness of around 1000 Å is desirable. In addition, the formation of the second layer consists of two layers of silicon oxide film in order to reduce the haze rate obtained by the first layer.
When forming a layered structure, it is desirable that the first layer has a haze rate of 2.5% or more. If the haze ratio of the first layer is less than 2.5%, the haze ratio becomes too small due to the coating of the second layer, and the effect of the uneven shape becomes undesirable. The present invention will be explained below based on examples. e Examples Example 1 A soda lime glass with a size of 100 (mm) x 100 (mm) and a thickness of 1 (mm) was immersed in a 0.5% concentration (wt%) HF aqueous solution for 10 minutes, and then thoroughly soaked. It was washed and dried to obtain a sample glass. Next, prepare an immersion tank for immersing the sample. The immersion tank consists of an outer tank 1 and an inner tank 2, and water 3 is filled between the inner tank and the outer tank. In the experiment, the water was heated with a heater 4 so that the temperature of this water was 35° C., and was stirred with a stirrer 5 to make the temperature distribution uniform. The inner tank consists of a front part 6, a middle part 7, and a rear part 8, and each part contains the treatment solution 3, which is saturated with silicon oxide in 2 mol/hydrosilicic acid and then diluted with water to 1 mol//. It's filled. The processing liquid in the rear part 8 of the inner tank is returned to the front part 6 of the inner tank by a circulation pump 10. Here, the ratio of the amount of processing liquid circulated per minute to the total amount of processing liquid was set to 8%. (Here, the total amount of treatment liquid is approximately 3, and the bottom area of the middle of the treatment tank is approximately 150 ^cm2 , so the liquid flow rate on the surface of the substrate glass to be immersed is expected to be approximately 1.6 cm/min.) An aqueous boric acid solution 11 having a concentration of 0.5 mol/min was continuously added dropwise to the reaction solution at a rate of 0.2 ml/min, and the mixture was maintained for 10 hours. Thereafter, the sample 9 is immersed and held vertically in the reaction solution in the center part 7 of the inner tank. Hold for 4 hours while continuing to circulate the reaction treatment solution and add the boric acid aqueous solution,
Thereafter, the sample was taken out, washed and dried. The thickness of the obtained film was approximately 1000 Å, and as a result of electron microscopy observation of the same film, the diameter was 300 to 5000 Å, and the height was
Numerous bowl-shaped irregularities measuring 200 to 3000 Å were observed. An electron micrograph at a magnification of approximately 10,700 times is shown in Figure 2. The overall effect of the shape of the unevenness and the number per unit area can be expressed as the degree of scattering (haze rate) for incident light. Here, the haze rate of the sample obtained above, which has uneven shapes on both the front and back sides, is 2%, and there is no unevenness on both sides of the sample.
This was a large value compared to the haze rate of 0.2% for the sample coated with a SiO ₂ film. Here, the haze rate is measured using the haze value measurement method (JIS,
K-6714 (1977)). Example 2 Except that the circulation rate of the processing solution was changed to 3% per minute of the total amount of processing solution (flow rate of processing solution approximately 0.6cm/min), and the immersion time of the sample was changed to 3 hours. Approximately 1000 Å was deposited on the sample using the same method as in Example 1.
A silicon oxide film with a thickness of . The obtained silicon oxide film was approximately 1000 Å thick, and electron microscope observation of the sample revealed that the sample had many approximately bowl-shaped irregularities with a diameter of 300 to 5000 Å and a height of 200 to 3000 Å, similar to those in Example 1. It has been confirmed that it exists. The haze rate of the above-mentioned sample, which had uneven shapes on both sides of the obtained sample, was 7%, and the sample obtained in Example 2 had a higher proportion of unevenness or unevenness with deeper arcs than the sample obtained in Example 1. It is expected that the number of Example 3 Substrate glass with a silicon oxide film having an uneven shape manufactured according to Example 2 (hereinafter referred to as A0)
Silicon oxide forming solution containing phosphorus (manufactured by Tokyo Ohka Kogyo Co., Ltd.)
(OCD solution) and then baked at 500°C to form a silicon oxide film with a thickness of about 1000 Å on both sides of the sample. (Hereafter this board will be referred to as A1) The haze rate is 7
% to 3%. Similarly, a silicon oxide film with a thickness of about 200 Å was formed on one side of the sample by sputtering on an A0 glass substrate. (Hereafter, this substrate will be referred to as A2) The haze rate changed from 7% to 6%. Separately, a glass substrate similar to that in Example 2 was immersed in a treatment solution in which boric acid was added to a saturated silicon oxide aqueous solution of hydrosilicofluoric acid to form a highly smooth silicon oxide film with a thickness of approximately 1000 Å.
Comparative board B was created. (Special request 1982)
-137217) An amorphous Si solar cell was created using these A0, A1, A2 substrates on the two-layer structure side, and B substrates.
The creation procedure is shown below. Monobutyltin trichloride vapor and CH ₃ CHF ₂ as dopant on substrates A0, A1, A2, B
A 2000 Å thick tin oxide transparent conductive film was formed by CVD using gas. Then monosilane (SiH ₄ )
(1) P-type semiconductor layer (boron-doped a-SiC:
(H, approximately 150 Å thick) (2) Intrinsic semiconductor layer (a-Si:H, approximately 5000 Å thick) (3) N-type semiconductor layer (phosphorus-doped microcrystalline Si (μc-Si): H, approximately 300 Å thick) Estimation is carried out in order, and finally the Al electrode (approximately
500 Å) by vapor deposition in vacuum (approximately 10 ^-4 Pa). When creating the above Al electrode, a mask with a hole of 2 mm in diameter was placed on the substrate, and 20 solar cells with a diameter of 2 mm were created. The electromotive force (open circuit voltage; V) when the obtained solar cell is irradiated with AM1 light of 100 mW/cm ² and the load is set to infinite, and the current value per unit surface area of the solar cell when the load is set to 0. (short circuit current; mA/cm ² ) and the percentage of solar cells exhibiting normal characteristics (survival rate;
%) was measured. Table 1 shows the measurement results obtained. As is clear from the table, it can be seen that the substrates A0, A1, and A2 using a silicon oxide film with an uneven shape exhibit a larger short circuit current value than the substrate B using a smooth silicon oxide film. In addition, by making the silicon oxide film have a two-layer structure, it is possible to provide a solar cell substrate with higher performance (less degree of open-circuit voltage drop) and higher survival rate when solar cells are created. Recognize. In the above example, glass containing silicon oxide was used as the base material, the shape was 100 mm x 100 mm, and the treatment process was performed intermittently, but since the silicon oxide film is an adhesive film, other glass plates Any material can be used, such as , plastic board, ceramic board, etc. In addition, the shape can be made larger than just 100mm x 100mm, and the processing process can be saturated with silicon oxide.

【表】状態が続く限り連続的に基材を浸漬することが出
来る。ここで、又上記実施例では、太陽電池基板とし
て基板の両面に凸凹形状の酸化珪素被膜を作成し
たが、少なくとも太陽電池を積層する側に凹凸形
状を持つていれば、太陽電池としての性能向上に
効果があることは言うまでもない。又太陽電池を
積層していない側の基板表面には、反射防止膜を
設けることが好ましいが、なくてもかまわない。
又、上記実施例のヘイズ率の測定値は基板両面に
凹凸を形成したものであり、片面に凹凸を制限し
た場合には約半分のヘイズ率を示すと考えられ
る。ｆ発明の効果本発明によれば、太陽電池基板として適当な凹
凸形状を有する太陽電池基板が、簡単な方法によ
り得られている。又２重のコート膜を作成するこ
とにより、特性のより向上した、生産性の高い太
陽電池基板を提供している。[Table] The substrate can be immersed continuously as long as the conditions continue. Here, and in the above example, a silicon oxide film with an uneven shape was created on both sides of the substrate as a solar cell substrate, but if the layer has an uneven shape at least on the side where solar cells are stacked, the performance as a solar cell can be improved. Needless to say, it is effective. Further, although it is preferable to provide an antireflection film on the surface of the substrate on the side on which the solar cells are not stacked, it is not necessary to provide an antireflection film.
Further, the measured value of the haze rate in the above example was obtained when unevenness was formed on both sides of the substrate, and it is thought that if the unevenness was limited to one side, the haze rate would be about half. f Effects of the Invention According to the present invention, a solar cell substrate having an uneven shape suitable for a solar cell substrate is obtained by a simple method. Furthermore, by creating a double coat film, a solar cell substrate with improved characteristics and high productivity is provided.

[Brief explanation of drawings]

第１図は本願発明の実施例を示す循環系統説明
図、第２図は実施例１により得られた太陽電池基
板表面の略おわん形粒子の構造を示す図面に代る
電子顕微鏡写真である。１……外槽、２……内槽、３……水、４……ヒ
ーター、５……撹拌器、６……内槽前部、７……
内槽中央部、８……内槽後部、９……ガラス、１
０……循環ポンプ、１１……ホウ酸水溶液。 FIG. 1 is an explanatory diagram of a circulation system showing an example of the present invention, and FIG. 2 is an electron micrograph in place of a drawing showing the structure of approximately bowl-shaped particles on the surface of a solar cell substrate obtained in Example 1. 1... Outer tank, 2... Inner tank, 3... Water, 4... Heater, 5... Stirrer, 6... Inner tank front, 7...
Center part of inner tank, 8...Rear part of inner tank, 9...Glass, 1
0... Circulation pump, 11... Boric acid aqueous solution.

Claims

[Claims] 1. The haze rate is 1% or more, and the diameter is 300 to 5000.
A solar cell substrate characterized by having a silicon oxide film having a large number of convex portions with a height of 200 to 3000 Å. 2. A patent claim in which the silicon oxide film having a large number of convex portions with a diameter of 300 to 5000 Å and a height of 200 to 3000 Å is a deposited film from a treatment solution obtained by adding boric acid to a saturated silicon oxide aqueous solution of hydrosilicofluoric acid. The solar cell substrate according to item 1. 3 A silicon oxide film with a large number of convex portions with a diameter of 300 to 5000 Å and a height of 200 to 3000 Å is deposited on a deposited film obtained by adding boric acid to a saturated silicon oxide aqueous solution of hydrosilicofluoric acid. Claim 1 is provided with a silicon oxide film having a uniform thickness of 50 to 2000 Å.
The solar cell substrate described in .