JPH09283778A - Solar cell - Google Patents

Solar cell

Info

Publication number
JPH09283778A
JPH09283778A JP8041697A JP4169796A JPH09283778A JP H09283778 A JPH09283778 A JP H09283778A JP 8041697 A JP8041697 A JP 8041697A JP 4169796 A JP4169796 A JP 4169796A JP H09283778 A JPH09283778 A JP H09283778A
Authority
JP
Japan
Prior art keywords
compound semiconductor
layer
solar cell
group
semiconductor 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
Application number
JP8041697A
Other languages
Japanese (ja)
Other versions
JP3027116B2 (en
Inventor
Takeshi Kitatani
健 北谷
Yoshiaki Yazawa
義昭 矢澤
Seiji Watabiki
誠次 綿引
Katsu Tamura
克 田村
Jiyunko Minemura
純子 峯邑
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP8041697A priority Critical patent/JP3027116B2/en
Publication of JPH09283778A publication Critical patent/JPH09283778A/en
Application granted granted Critical
Publication of JP3027116B2 publication Critical patent/JP3027116B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy

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  • Photovoltaic Devices (AREA)

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency by reducing the recombination loss due to the interface product owing to the group V element switching at the time of forming a film. SOLUTION: Second III-V compound semiconductor containing other group V element as a constituent is laminated as the window layer 3 and BSF layer 6 materials of a solar cell (n-type region 4 and p-type region 5) formed of p-n junction of first III-V compound semiconductor. Third III-V compound semiconductor layer 9 containing both group V elements for constituting at least larger forbidden band width than one of the first and second semiconductors and having the forbidden band width is introduced into the heterointerface.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の属する技術分野】本発明は、太陽電池及びその
製造方法に関するものである。
TECHNICAL FIELD The present invention relates to a solar cell and a method for manufacturing the same.

【0002】[0002]

【従来の技術】太陽電池は半導体のpn接合を基本構造
とし、入射光によりpn接合領域に励起されたキャリア
が拡散して半導体内を伝導し内部電界領域に達した後、
その内部電界によって電子はn側の電極へ、正孔はp側
の電極へ到達し、そこから外部に取り出されることによ
り出力が得られる。
2. Description of the Related Art A solar cell has a semiconductor pn junction as a basic structure, and carriers excited in a pn junction region by incident light are diffused and conducted in the semiconductor to reach an internal electric field region.
Due to the internal electric field, electrons reach the n-side electrode and holes reach the p-side electrode, and the electrons are taken out to obtain an output.

【0003】図2は、現在製造されている砒化ガリウム
(GaAs)太陽電池の構造を示す略断面図である。そ
の基本構成はGaAsのエミッターn型層4とベースp
型層5より形成されるpn接合層であるが、キャリアの
再結合損失を低下させるため、GaAsと同じ格子定数
を持ち、良好な界面を形成するガリウムインジウム燐
(Ga0.5In0.5P)を導入したヘテロ構造となってい
る。図においてエミッター層4の上に積層されたGa
0.5In0.5P層3は一般に窓層と呼ばれている。この窓
層3は、光生成キャリアが表面に到達しないようにして
表面再結合損失を低減させるための層である。またベー
ス層5の下に積層されたGa0.5In0.5P層6は裏面電
界(BSF)層と呼ばれ、裏面に到達するキャリアを追
い返し裏面での再結合損失を低減させるための層であ
り、生成キャリアの収集効率を高めるためには不可欠な
層である。
FIG. 2 is a schematic sectional view showing the structure of a currently manufactured gallium arsenide (GaAs) solar cell. The basic structure is GaAs emitter n-type layer 4 and base p.
Although it is a pn junction layer formed of the type layer 5, gallium indium phosphide (Ga 0.5 In 0.5 P) having the same lattice constant as GaAs and forming a good interface is introduced in order to reduce the recombination loss of carriers. It has a heterostructure. In the figure, Ga stacked on the emitter layer 4
The 0.5 In 0.5 P layer 3 is generally called a window layer. The window layer 3 is a layer for preventing the photo-generated carriers from reaching the surface and reducing the surface recombination loss. Further, the Ga 0.5 In 0.5 P layer 6 laminated under the base layer 5 is called a back surface field (BSF) layer and is a layer for repelling carriers reaching the back surface and reducing recombination loss on the back surface. It is an indispensable layer for improving the collection efficiency of the generated carriers.

【0004】[0004]

【発明が解決しようとする課題】前述のように、周期律
表のIII族元素及びV族元素から成る化合物半導体太陽
電池は、異種の半導体材料を積層するヘテロ構造で構成
されるのが一般的であり、その製造手段としては有機金
属化学気相成長(MOCVD)法あるいは分子線エピタ
キシー(MBE)法といった成長法が現在主流である。
この場合の膜成長過程は、蒸気圧の高いV族元素で覆わ
れた成長基板表面にIII族元素が到達し、結合すること
によって進行していく。
As described above, a compound semiconductor solar cell composed of a Group III element and a Group V element of the periodic table is generally composed of a hetero structure in which different kinds of semiconductor materials are laminated. As a manufacturing method thereof, a growth method such as a metal organic chemical vapor deposition (MOCVD) method or a molecular beam epitaxy (MBE) method is currently the mainstream.
In this case, the film growth process proceeds by the group III element reaching and binding to the surface of the growth substrate covered with the group V element having a high vapor pressure.

【0005】ここで、図2に示した従来の太陽電池製造
の際の成膜シーケンスを考えると、例えばBSF層6か
らベース層5へかけてのGa0.5In0.5P層からGaA
s層の成長の際には、V族元素である燐(P)から砒素
(As)への切替えが必要となる。前述したようにV族
元素であるPやAsは蒸気圧が高く、この場合、Pの供
給をシャッター操作等の方法で遮断したとしても、それ
が払拭されるまでにはある程度の時間がかかる。
Here, considering the film forming sequence in manufacturing the conventional solar cell shown in FIG. 2, for example, from the Ga 0.5 In 0.5 P layer to the GaA layer from the BSF layer 6 to the base layer 5.
During the growth of the s layer, it is necessary to switch from the group V element phosphorus (P) to arsenic (As). As described above, P and As, which are group V elements, have a high vapor pressure, and in this case, even if the supply of P is shut off by a method such as a shutter operation, it takes some time to wipe it off.

【0006】そこで、通常V族元素切替え時には元素供
給の無い、いわゆる中断時間を設けている。この中断時
間が短いと、次に供給されるAsとの反応でガリウムイ
ンジウム砒素燐(GaInAsP)といったV族元素が
入り交じった界面生成物が形成されてしまう。一方、中
断時間が長い場合には、その間にGa0.5In0.5P膜表
面からのPの再蒸発、いわゆるV族ぬけが顕著に起こ
り、次に供給されるAsとの反応でやはりGaInAs
Pが形成される。この層はGa0.5In0.5P及びGaA
sよりも狭い禁制帯幅を有するため、伝導キャリアの再
結合領域となり、その結果太陽電池の効率は低下してし
まう。エミッター層4から窓層3の成長に際しても同様
のことが言える。
Therefore, a so-called interruption time during which no element is supplied is usually provided when the group V element is switched. If this interruption time is short, an interface product in which Group V elements such as gallium indium arsenide phosphide (GaInAsP) are mixed with each other is formed by the reaction with As supplied next. On the other hand, when the interruption time is long, re-evaporation of P from the surface of the Ga 0.5 In 0.5 P film, that is, so-called group V escape occurs remarkably, and GaInAs is also reacted by the reaction with As supplied next.
P is formed. This layer is made of Ga 0.5 In 0.5 P and GaA.
Since it has a forbidden band width narrower than s, it becomes a recombination region of conductive carriers, resulting in a decrease in efficiency of the solar cell. The same applies to the growth of the window layer 3 from the emitter layer 4.

【0007】以上のように周期律表のIII族元素及びV
族元素から成る第1の化合物半導体と、それとは異なる
V族元素を構成元素とする第2のIII−V族化合物半導
体とのヘテロ接合を構成要素とする太陽電池において、
膜成長時のV族元素の切替に起因する太陽電池の効率低
下は大きな問題である。本発明の目的は、上記従来技術
の問題を解決するため、ヘテロ界面での損失を低減する
に最適な太陽電池構造を提案することにある。
As described above, Group III elements and V of the periodic table
A solar cell having a heterojunction of a first compound semiconductor made of a group element and a second III-V group compound semiconductor having a group V element different from the first group as a constituent element,
The decrease in the efficiency of the solar cell due to the switching of the group V element during the film growth is a big problem. An object of the present invention is to propose an optimal solar cell structure for reducing the loss at the hetero interface in order to solve the above-mentioned problems of the conventional technology.

【0008】[0008]

【課題を解決するための手段】本発明は、上記目的を達
成するため、周期律表のIII族元素及びV族元素から成
る第1の化合物半導体上に、それとは異なるV族元素を
構成元素とする第2のIII−V族化合物半導体を積層す
る構造を有する太陽電池において、その界面に第1及び
第2の化合物半導体の少なくとも一方より大きい禁制帯
幅を有し、かつ、それらを構成するV族元素の両方を構
成元素とする第3のIII−V族化合物半導体層を導入し
た太陽電池構造を提案するものである。このような精密
な膜制御を必要とする素子構造の作製には分子線エピタ
キシー(MBE)法や有機金属化学気相成長(MOCV
D)法等の成長法が適している。
In order to achieve the above object, the present invention provides a group V element different from the group V element on a first compound semiconductor composed of a group III element and a group V element of the periodic table. In a solar cell having a structure in which a second III-V group compound semiconductor is laminated, the band gap is larger than at least one of the first and second compound semiconductors at the interface, and they are configured. The present invention proposes a solar cell structure in which a third III-V group compound semiconductor layer having both V group elements as constituent elements is introduced. In order to fabricate a device structure requiring such precise film control, a molecular beam epitaxy (MBE) method or a metal organic chemical vapor deposition (MOCV) method is used.
A growth method such as the D) method is suitable.

【0009】上記従来技術の問題点は膜成長時のV族元
素雰囲気の切替の困難さに起因しているため、それを逆
に利用し、第1及び第2の化合物半導体に含まれるV族
元素の両方を含む化合物半導体層をその界面に導入する
ことはたやすい。例えば、図2に示したようなGa0.5
In0.5Pを窓層3及びBSF層6とするGaAs太陽
電池の場合においては、第3のIII−V族化合物半導体
層9としてガリウム砒素燐(GaAsP)あるいはアル
ミニウムガリウム砒素燐(AlGaAsP)等が適して
おり、その導入部はGa0.5In0.5P層とGaAs層と
のヘテロ接合の3箇所であり、それを図1に示した。
Since the problem of the above-mentioned prior art is caused by the difficulty of switching the atmosphere of the group V element during the film growth, it is used to the contrary and the group V elements contained in the first and second compound semiconductors are used. It is easy to introduce a compound semiconductor layer containing both elements at its interface. For example, Ga 0.5 as shown in FIG.
In the case of a GaAs solar cell using In 0.5 P as the window layer 3 and the BSF layer 6, gallium arsenide phosphide (GaAsP) or aluminum gallium arsenide phosphide (AlGaAsP) or the like is suitable for the third III-V compound semiconductor layer 9. The introduction portion is at three points of the heterojunction between the Ga 0.5 In 0.5 P layer and the GaAs layer, which is shown in FIG.

【0010】本発明の太陽電池構造によると、膜成長時
のV族元素の切替に起因する効率低下の問題を解決する
ことが可能である。図1の断面構造を有する太陽電池を
例にとり、図3のエネルギーバンド図を参照してその作
用について説明する。図3において、(a)は図2に示
した従来構造における窓層3、エミッター層4、ベース
層5、BSF層6の理想状態のエネルギーバンド図、
(b)は実際に作製した素子におけるエネルギーバンド
図、(c)は本発明の構造におけるP原子の混晶比が大
きいGaAsP層導入の(第3の化合物半導体の禁制帯
幅が、第1の化合物半導体と第2の化合物半導体のどち
らよりも大きい)場合のエネルギーバンド図、(d)は
P原子の混晶比が小さいGaAsP層導入(第3の化合
物半導体の禁制帯幅が、第1の化合物半導体あるいは第
2の化合物半導体のどちらかより大きい)の場合のエネ
ルギーバンド図をそれぞれ示している。ただし、図にお
いてはヘテロ界面における禁制帯幅の差に起因するバン
ドの曲がりは省略し、実効的なエネルギー差のみを示し
た。
According to the solar cell structure of the present invention, it is possible to solve the problem of efficiency decrease due to switching of the group V element during film growth. Taking a solar cell having the cross-sectional structure of FIG. 1 as an example, its operation will be described with reference to the energy band diagram of FIG. In FIG. 3, (a) is an energy band diagram in an ideal state of the window layer 3, the emitter layer 4, the base layer 5, and the BSF layer 6 in the conventional structure shown in FIG.
(B) is an energy band diagram of an actually manufactured device, and (c) is a GaAsP layer introduced with a large mixed crystal ratio of P atoms in the structure of the present invention (the forbidden band width of the third compound semiconductor is An energy band diagram in the case of being larger than both of the compound semiconductor and the second compound semiconductor, (d) shows the introduction of a GaAsP layer in which the mixed crystal ratio of P atoms is small (the forbidden band width of the third compound semiconductor is The energy band diagram in the case of either the compound semiconductor or the second compound semiconductor) is shown. However, in the figure, the bending of the band due to the difference in the forbidden band width at the hetero interface is omitted, and only the effective energy difference is shown.

【0011】理想状態では図3(a)のようになり、素
子の奥深くで生成された電子も裏面のBSF層6にはね
かえされ、表面のn層側へ到達することができる。ま
た、正孔は裏面方向へ損失なく伝導する。よって、ヘテ
ロ構造導入の効果によりキャリアの収集効率は高くなる
ことが期待できる。しかし、実際に作製すると、ヘテロ
界面にGaInAsP等の生成物が形成されてしまう。
このときのエネルギーバンドは、禁制帯幅の狭い領域を
含んだ(b)に示すようになる。伝導するキャリアは電
極に到達する前にエネルギーの低い領域に捕らえられて
しまうので、再結合損失が増大し、太陽電池の性能は低
下する。
In an ideal state, as shown in FIG. 3A, electrons generated deep inside the device are also repelled by the BSF layer 6 on the back surface and can reach the n-layer side on the front surface. In addition, holes are conducted to the back surface without loss. Therefore, it can be expected that the efficiency of carrier collection is increased by the effect of introducing the heterostructure. However, when actually manufactured, a product such as GaInAsP is formed at the hetero interface.
The energy band at this time is as shown in (b) including a region with a narrow forbidden band. Since the conducting carriers are trapped in the low energy region before reaching the electrode, the recombination loss increases and the performance of the solar cell deteriorates.

【0012】一方、本発明の構造では第3の化合物半導
体層9を導入し、界面生成物が形成される領域を禁制帯
幅の大きい領域に置き換えることにより、従来構造にお
ける再結合損失を低減する。図3(c)、(d)に示し
たように、導入する第3の化合物半導体層としては2種
類が考えられる。まず、P原子の混晶比が大きいGaA
sPのように第3の化合物半導体の禁制帯幅が、第1の
化合物半導体と第2の半導体のそれのどちらよりも大き
い層を導入した場合には(c)にようになる。また、P
原子の混晶比が小さいGaAsPのように第3の化合物
半導体の禁制帯幅が、第1の化合物半導体あるいは第2
の化合物半導体のそれのどちらかより大きい層を導入し
た場合には(d)のようになる。いずれの場合にも再結
合領域が消滅し、従来構造における損失を低減すること
ができる。特に(c)においては、導入した第3の化合
物半導体層9が少数キャリアに対してより大きなBSF
効果を示す。AlGaAsP層導入の場合にも、その組
成比によって(c)と(d)の両方が可能である。
On the other hand, in the structure of the present invention, the third compound semiconductor layer 9 is introduced and the region where the interface product is formed is replaced with the region having a large forbidden band width, thereby reducing the recombination loss in the conventional structure. . As shown in FIGS. 3C and 3D, two types can be considered as the third compound semiconductor layer to be introduced. First, GaA with a large mixed crystal ratio of P atoms
When a layer such as sP in which the forbidden band width of the third compound semiconductor is larger than that of either the first compound semiconductor or the second semiconductor is introduced as shown in (c). Also, P
The forbidden band width of the third compound semiconductor, such as GaAsP having a small mixed crystal ratio of atoms, is the first compound semiconductor or the second compound semiconductor.
(D) is obtained when a layer larger than either of the compound semiconductors is introduced. In either case, the recombination region disappears, and the loss in the conventional structure can be reduced. Particularly in (c), the introduced third compound semiconductor layer 9 has a larger BSF with respect to minority carriers.
Show the effect. Even when the AlGaAsP layer is introduced, both (c) and (d) are possible depending on the composition ratio.

【0013】また、このとき第3の化合物半導体層を、
第1の化合物半導体層及び第2の化合物半導体層よりも
屈折率の小さい材料とすれば、従来構造よりヘテロ界面
における屈折率差を大きくして、光の閉じ込め効率を向
上させることができる。以上の作用により、本発明の構
造においては理想的な素子に近い高いキャリアの収集効
率が実現でき、高効率の太陽電池の作製が可能となる。
At this time, the third compound semiconductor layer is
By using a material having a smaller refractive index than the first compound semiconductor layer and the second compound semiconductor layer, the refractive index difference at the hetero interface can be made larger than that in the conventional structure, and the light confinement efficiency can be improved. With the above operation, in the structure of the present invention, high carrier collection efficiency close to that of an ideal element can be realized, and a highly efficient solar cell can be manufactured.

【0014】[0014]

【発明の実施の形態】以下、本発明の実施の形態につい
て説明する。 [実施の形態1]図2に示した従来構造の太陽電池にお
いて、Ga0.5In0.5PからGaAsへの切り替えの際
及びGaAsからGa0.5In0.5Pへの切り替えの際に
本発明を適用して図1に断面構造を略示する太陽電池を
製造した。成長方法はガスソースMBE(GS−MB
E)法とした。これはV族元素の供給に気体原料を用い
る方法である。ここではAsに関してアルシン(AsH
3)、Pに関してホスフィン(PH3)を熱クラッキング
して用いた。作製する半導体基板はp型のGaAs(1
00)基板である。
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. In the solar cell of the conventional structure shown in FIG. 2 Embodiment 1, by applying the present invention from the switching of the time and GaAs to GaAs from Ga 0.5 In 0.5 P when switching to Ga 0.5 In 0.5 P A solar cell whose sectional structure is schematically shown in FIG. 1 was manufactured. The growth method is gas source MBE (GS-MB
E) method. This is a method in which a gaseous raw material is used to supply the group V element. Here, regarding As, arsine (AsH
3 ), for P, phosphine (PH 3 ) was used after thermal cracking. The semiconductor substrate to be manufactured is p-type GaAs (1
00) Substrate.

【0015】AsH3供給下のAs雰囲気において、G
aAs基板8の表面の酸化膜を580℃、10分の熱ク
リーニングにより除去した後、GaとBeのシャッター
を開き、同一温度にて基板8上にバッファー層7として
ベリリウム(Be)をドープしたp型GaAs層(ドー
プ濃度7×1018cm-3)を0.3μm成長させた。そ
の後、基板温度を500℃まで低下させ、GaとIn及
びBeのシャッターを同時に開き、BSF層6としてB
eをドープしたp型Ga0.5In0.5P層(ドープ濃度
4.5×1018cm-3)を0.1μm成長させた。BS
F層6の成長終了後、Inシャッターを先に閉じ、Ga
シャッターを開いたままPとAsを同時に供給し第3の
化合物半導体層9としてGaAsP層を形成した。この
ように第3の化合物半導体層9の導入は、シャッター操
作のみで非常に容易に実現できる。第3の化合物半導体
層9の膜厚は1nm程度で十分な効果が得られる。
In an As atmosphere under the supply of AsH 3 , G
After the oxide film on the surface of the aAs substrate 8 was removed by thermal cleaning at 580 ° C. for 10 minutes, the shutters for Ga and Be were opened, and the substrate 8 was doped with beryllium (Be) as a buffer layer 7 at the same temperature. Type GaAs layer (dope concentration 7 × 10 18 cm −3 ) was grown to 0.3 μm. After that, the substrate temperature is lowered to 500 ° C., the Ga, In and Be shutters are simultaneously opened to form the BSF layer 6 as B.
An e-doped p-type Ga 0.5 In 0.5 P layer (doping concentration 4.5 × 10 18 cm −3 ) was grown to 0.1 μm. BS
After the growth of the F layer 6 is completed, the In shutter is closed first, and
With the shutter open, P and As were simultaneously supplied to form a GaAsP layer as the third compound semiconductor layer 9. In this way, the introduction of the third compound semiconductor layer 9 can be realized very easily only by operating the shutter. A sufficient effect can be obtained when the thickness of the third compound semiconductor layer 9 is about 1 nm.

【0016】次に基板温度を580℃とし、Beをドー
プしたp型GaAsベース層5(ドープ濃度2×1017
cm-3)を3.0μm、続いて珪素(Si)をドープし
たn型GaAsエミッター層4(ドープ濃度2×1018
cm-3)を0.1μm成長させた。その後、GaとAs
のシャッターと同時にPのシャッターを開き、再び第3
の化合物半導体層9としてGaAsP層を導入した。そ
して基板温度を再び500℃まで低下させ、温度安定
後、窓層3としてSiをドープしたn型Ga0.5In0.5
P層(ドープ濃度2×1018cm-3)を0.03μm成
長させた。窓層3の成長後にも同様にして第3の化合物
半導体層9を導入した。最後に、Siをドープしたn型
GaAsキャップ層2(ドープ濃度3×1018cm-3
を0.5μm成長させた。
Next, the substrate temperature was set to 580 ° C. and the Be-doped p-type GaAs base layer 5 (dope concentration 2 × 10 17
cm −3 ) of 3.0 μm, followed by silicon (Si) -doped n-type GaAs emitter layer 4 (doping concentration 2 × 10 18
cm −3 ) was grown to 0.1 μm. After that, Ga and As
The shutter of P is opened at the same time as the shutter of, and the third
A GaAsP layer was introduced as the compound semiconductor layer 9. Then, the substrate temperature is lowered to 500 ° C. again, and after the temperature is stabilized, Si-doped n-type Ga 0.5 In 0.5 is used as the window layer 3.
A P layer (dope concentration 2 × 10 18 cm −3 ) was grown to 0.03 μm. The third compound semiconductor layer 9 was similarly introduced after the growth of the window layer 3. Finally, Si-doped n-type GaAs cap layer 2 (doping concentration 3 × 10 18 cm −3 )
Was grown to 0.5 μm.

【0017】このようにして作製した太陽電池の量子効
率を、図2に示した従来の太陽電池の量子効率を1とし
て相対的に比較した結果を図4に示す。図4から明らか
なように、本発明による太陽電池は、短波長側及び長波
長側の量子効率に顕著な向上が見られる。また、最近タ
ンデム型太陽電池のボトムセルとして注目を集めている
ガリウムインジウム砒素(Ga0.5In0.5As)太陽電
池においては、インジウム燐(InP)を窓層3及びB
SF層6として用いており、第3の化合物半導体層9と
して適正な組成比のインジウム砒素燐(InAsP)あ
るいはアルミニウムインジウム砒素燐(AlInAs
P)を導入することによって同様の効果が得られる。 [実施の形態2]界面損失低減とともに光閉じ込め効率
も向上させた太陽電池を作製した。光閉じ込め効率を向
上させるには、第3の化合物半導体として第1及び第2
の化合物半導体よりも屈折率の小さな材料を選択するこ
とが必要であり、その屈折率が小さいほど閉じこめ効率
は上がる。屈折率低下にはAlの導入が有効である。こ
こでは、第3の化合物半導体層としてGaAsP層に代
えてAlGaAsP層を用いた以外は実施の形態1と同
様の、図1に断面構造を略示する太陽電池を作製した。
FIG. 4 shows the results of a relative comparison between the quantum efficiencies of the solar cells thus produced and the quantum efficiency of the conventional solar cell shown in FIG. As is clear from FIG. 4, the solar cell according to the present invention shows a remarkable improvement in quantum efficiency on the short wavelength side and the long wavelength side. In gallium indium arsenide (Ga 0.5 In 0.5 As) solar cells, which have recently attracted attention as bottom cells for tandem solar cells, indium phosphide (InP) is used as the window layers 3 and B.
It is used as the SF layer 6 and has an appropriate composition ratio as the third compound semiconductor layer 9 such as indium arsenic phosphide (InAsP) or aluminum indium arsenide phosphide (AlInAs).
A similar effect is obtained by introducing P). [Embodiment 2] A solar cell having a reduced interface loss and an improved light confinement efficiency was manufactured. In order to improve the light confinement efficiency, the first and second compound semiconductors are used as the third compound semiconductor.
It is necessary to select a material having a smaller refractive index than that of the compound semiconductor, and the smaller the refractive index, the higher the confinement efficiency. Introduction of Al is effective for lowering the refractive index. Here, a solar cell similar to that of the first embodiment except that the AlGaAsP layer was used as the third compound semiconductor layer in place of the GaAsP layer was produced, the cross-sectional structure of which is schematically shown in FIG.

【0018】Beをドープしたp型Ga0.5In0.5P層
(ドープ濃度4.5×1018cm-3)からなるBSF層
6とBeをドープしたp型GaAsベース層5(ドープ
濃度2×1017cm-3)との界面へのAlGaAsP層
の導入は、BSF層6の成長終了後、Inシャッターを
先に閉じ、Gaシャッターを開いたままP,As及びA
lを同時に供給することで行った。Siをドープしたn
型GaAsエミッター層4(ドープ濃度2×1018cm
-3)とSiをドープしたn型Ga0.5In0.5P窓層3
(ドープ濃度2×1018cm-3)の界面へのAlGaA
sP層の導入は、エミッター層4の成長終了後、Gaシ
ャッター及びAsシャッターを開いたままP及びAlを
同時に供給することで行った。窓層3の成長後にも、同
様にして第3の化合物半導体層9としてAlGaAsP
層を導入した。第3の化合物半導体層9の膜厚はいずれ
も約1nmとした。
A BSF layer 6 made of a Be-doped p-type Ga 0.5 In 0.5 P layer (dope concentration 4.5 × 10 18 cm -3 ) and a Be-doped p-type GaAs base layer 5 (dope concentration 2 × 10 5 The AlGaAsP layer is introduced to the interface with 17 cm −3 ) after the growth of the BSF layer 6 is completed, the In shutter is closed first, and the Ga shutter is kept open to remove P, As and A.
It was carried out by supplying 1 at the same time. N doped with Si
Type GaAs emitter layer 4 (dope concentration 2 × 10 18 cm
-3 ) and Si-doped n-type Ga 0.5 In 0.5 P window layer 3
AlGaA on the interface of (dope concentration 2 × 10 18 cm −3 ).
The introduction of the sP layer was performed by supplying P and Al at the same time with the Ga shutter and As shutter open after the growth of the emitter layer 4 was completed. Even after the growth of the window layer 3, AlGaAsP is similarly used as the third compound semiconductor layer 9.
The layers were introduced. The thickness of each of the third compound semiconductor layers 9 was about 1 nm.

【0019】図1に示すように、このような3種類の半
導体層の組がエミッタ層4及びベース層5を挟んで2組
存在するダブルヘテロ構造では、光の閉じこめ効率がよ
り高くなりキャリアの収集効率が上がる。ここで作製し
た太陽電池は、第3の化合物半導体層9としてAlGa
AsP層を用いたことにより、GaAsP層を用いた実
施の形態1の太陽電池に比較して量子効率が全体的に数
%向上した。同様の効果はGa0.5In0.5As太陽電池
において第3の半導体層としてAlInAsP層を用い
た場合にも得られる。
As shown in FIG. 1, in the double heterostructure in which two sets of such three types of semiconductor layers exist with the emitter layer 4 and the base layer 5 sandwiched therebetween, the light confinement efficiency becomes higher, and the carrier concentration increases. Collection efficiency increases. The solar cell manufactured here has AlGa as the third compound semiconductor layer 9.
By using the AsP layer, the quantum efficiency as a whole was improved by several% as compared with the solar cell of the first embodiment using the GaAsP layer. The same effect can be obtained when an AlInAsP layer is used as the third semiconductor layer in a Ga 0.5 In 0.5 As solar cell.

【0020】[0020]

【発明の効果】本発明によれば、成長時のV族元素切替
えに起因する界面生成物による再結合損失を低減し、高
効率の太陽電池を作製することができる。
According to the present invention, it is possible to reduce the recombination loss due to the interface product due to the switching of the group V element during the growth and to manufacture a highly efficient solar cell.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明による太陽電池の断面構造図。FIG. 1 is a sectional structural view of a solar cell according to the present invention.

【図2】従来の太陽電池の断面構造図。FIG. 2 is a cross-sectional structural diagram of a conventional solar cell.

【図3】各素子のエネルギーバンドの説明図であり、
(a)は理想構造の場合、(b)は実際の素子の場合、
(c)はP原子の混晶比が大きいGaAsP層導入の場
合、(d)はP原子の混晶比が小さいGaAsP層導入
の場合を示す。
FIG. 3 is an explanatory diagram of energy bands of each element,
(A) is an ideal structure, (b) is an actual element,
(C) shows the case of introducing a GaAsP layer having a large mixed crystal ratio of P atoms, and (d) shows the case of introducing a GaAsP layer having a small mixed crystal ratio of P atoms.

【図4】本発明による太陽電池の相対量子効率を従来例
を1として示した図。
FIG. 4 shows the relative quantum efficiency of the solar cell according to the present invention as Conventional Example 1.

【符号の説明】[Explanation of symbols]

1…表面電極、2…キャップ層、3…窓層、4…エミッ
ター層、5…ベース層、6…BSF、7…バッファー
層、8…半導体基板、9…第3の化合物半導体層
DESCRIPTION OF SYMBOLS 1 ... Surface electrode, 2 ... Cap layer, 3 ... Window layer, 4 ... Emitter layer, 5 ... Base layer, 6 ... BSF, 7 ... Buffer layer, 8 ... Semiconductor substrate, 9 ... Third compound semiconductor layer

───────────────────────────────────────────────────── フロントページの続き (72)発明者 田村 克 東京都国分寺市東恋ヶ窪一丁目280番地 株式会社日立製作所中央研究所内 (72)発明者 峯邑 純子 東京都国分寺市東恋ヶ窪一丁目280番地 株式会社日立製作所中央研究所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsura Tamura 1-280 Higashi Koigakubo, Kokubunji City, Tokyo Inside Hitachi Central Research Laboratory (72) Inventor Junko Minupura 1-280 Higashi Koigakubo, Kokubunji City, Tokyo Hitachi, Ltd. Central Research Center

Claims (7)

【特許請求の範囲】[Claims] 【請求項1】 周期律表のIII−V族元素から成る第1
の化合物半導体層と、それとは異なるV族元素を構成元
素とする第2のIII−V族化合物半導体層とを積層する
構造を有する太陽電池において、前記第1の化合物半導
体層と第2の化合物半導体層との界面に前記第1及び第
2の化合物半導体の少なくとも一方より大きい禁制帯幅
を有し、前記第1及び第2の化合物半導体層を構成する
V族元素の両方を構成元素とする第3のIII−V族化合
物半導体層を導入したことを特徴とする太陽電池。
1. A first element comprising a III-V group element of the periodic table.
A compound semiconductor layer and a second III-V group compound semiconductor layer having a group V element different from that as a constituent element are stacked, the first compound semiconductor layer and the second compound The forbidden band width is larger than at least one of the first and second compound semiconductors at the interface with the semiconductor layer, and both of the group V elements constituting the first and second compound semiconductor layers are constituent elements. A solar cell having a third III-V compound semiconductor layer introduced therein.
【請求項2】 前記第3の化合物半導体層は、前記第1
の化合物半導体層及び第2の化合物半導体層より小さい
屈折率を有することを特徴とする請求項1記載の太陽電
池。
2. The third compound semiconductor layer is the first compound semiconductor layer.
The solar cell according to claim 1, which has a refractive index smaller than that of the compound semiconductor layer and the second compound semiconductor layer.
【請求項3】 前記第1、第2、第3の化合物半導体層
の組をpn接合層を挟んで2組有することを特徴とする
請求項2記載の太陽電池。
3. The solar cell according to claim 2, wherein there are two sets of the first, second, and third compound semiconductor layers with a pn junction layer interposed therebetween.
【請求項4】 前記第1の化合物半導体がガリウムイン
ジウム燐であり、前記第2の化合物半導体がガリウム砒
素であり、前記第3の化合物半導体がガリウム砒素燐で
あることを特徴とする請求項1、2又は3記載の太陽電
池。
4. The first compound semiconductor is gallium indium phosphide, the second compound semiconductor is gallium arsenide, and the third compound semiconductor is gallium arsenide phosphide. 2. The solar cell according to 2 or 3.
【請求項5】 前記第1の化合物半導体がガリウムイン
ジウム燐であり、前記第2の化合物半導体がガリウム砒
素であり、前記第3の化合物半導体がアルミニウムガリ
ウム砒素燐であることを特徴とする請求項1、2又は3
記載の太陽電池。
5. The first compound semiconductor is gallium indium phosphide, the second compound semiconductor is gallium arsenide, and the third compound semiconductor is aluminum gallium arsenide phosphide. 1, 2 or 3
The solar cell as described.
【請求項6】 前記第1の化合物半導体がガリウムイン
ジウム砒素であり、前記第2の化合物半導体がインジウ
ム燐であり、前記第3の化合物半導体がインジウム砒素
燐であることを特徴とする請求項1、2又は3記載の太
陽電池。
6. The first compound semiconductor is gallium indium arsenide, the second compound semiconductor is indium phosphide, and the third compound semiconductor is indium arsenide phosphide. 2. The solar cell according to 2 or 3.
【請求項7】 前記第1の化合物半導体がガリウムイン
ジウム砒素であり、前記第2の化合物半導体がインジウ
ム燐であり、前記第3の化合物半導体がアルミニウムイ
ンジウム砒素燐であることを特徴とする請求項1、2又
は3記載の太陽電池。
7. The first compound semiconductor is gallium indium arsenide, the second compound semiconductor is indium phosphide, and the third compound semiconductor is aluminum indium arsenide phosphide. The solar cell according to 1, 2, or 3.
JP8041697A 1996-02-28 1996-02-28 Solar cell Expired - Fee Related JP3027116B2 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012140120A (en) * 2010-12-30 2012-07-26 Thales Expandable planar solar generator
JP2013183159A (en) * 2012-02-29 2013-09-12 Boeing Co:The Solar cell with delta doping layer
WO2019124012A1 (en) * 2017-12-18 2019-06-27 国立研究開発法人産業技術総合研究所 Solar cell

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015159613A (en) * 2015-05-01 2015-09-03 富士通株式会社 Portable device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60218881A (en) * 1984-04-13 1985-11-01 Nippon Telegr & Teleph Corp <Ntt> Gaas solar battery
JPS63261882A (en) * 1987-04-20 1988-10-28 Nippon Telegr & Teleph Corp <Ntt> Semiconductor element
JPH0236536A (en) * 1988-07-27 1990-02-06 Hitachi Ltd Semiconductor device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60218881A (en) * 1984-04-13 1985-11-01 Nippon Telegr & Teleph Corp <Ntt> Gaas solar battery
JPS63261882A (en) * 1987-04-20 1988-10-28 Nippon Telegr & Teleph Corp <Ntt> Semiconductor element
JPH0236536A (en) * 1988-07-27 1990-02-06 Hitachi Ltd Semiconductor device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012140120A (en) * 2010-12-30 2012-07-26 Thales Expandable planar solar generator
JP2013183159A (en) * 2012-02-29 2013-09-12 Boeing Co:The Solar cell with delta doping layer
JP2018107453A (en) * 2012-02-29 2018-07-05 ザ・ボーイング・カンパニーThe Boeing Company Solar cell with delta doping layer
US10944022B2 (en) 2012-02-29 2021-03-09 The Boeing Company Solar cell with delta doping layer
WO2019124012A1 (en) * 2017-12-18 2019-06-27 国立研究開発法人産業技術総合研究所 Solar cell

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