CN103633181B - A kind of solar cell containing II type hetero-junctions Window layer - Google Patents

Abstract

The invention discloses a kind of solar cell containing II type hetero-junctions Window layer, this solar cell, adopting can with the semi-conducting material of the launch site material formation II type hetero-junctions Window layer as broad-band gap solar cell.Window layer adopts the GaAsP of n-type, and window layer thickness is 10 ~ 50nm.Launch site adopts n-type AlGaInP, and launch site thickness is 40 ~ 100nm.Solar cell containing II type hetero-junctions Window layer provided by the invention, can solve the window layer material select permeability in ultra-wide band gap solar cell, and the development for tying efficient solar battery improves guarantee more.

Description

Translated fromChinese

一种含有II型异质结窗口层的太阳电池A solar cell containing a type II heterojunction window layer

技术领域technical field

本发明涉及一种太阳电池，具体地，涉及一种含有II型异质结窗口层的太阳电池。The invention relates to a solar cell, in particular to a solar cell containing a type II heterojunction window layer.

背景技术Background technique

太阳电池可将太阳能直接转换为电能，是当前利用绿色能源的最有效方式之一。III-V族半导体太阳电池相较于传统的硅太阳电池，其转换效率高、抗辐照能力强、温度特性好等优点，被公认为是新一代高性能长寿命空间主电源，已在航天领域得到广泛应用。随着化合物半导体生长技术(如金属有机化合物汽相外延——MOCVD)的不断进步，III-V族太阳电池的效率得到了很大提高，多结太阳电池效率已经超过34%。如何进一步提升III-V族太阳电池的转换效率成为当前研究热点。窗口层的引入在发射区表面形成了良好的钝化界面，提高了短路电流密度，同时提高了开路电压，并且窗口层需要选择带隙大于发射区的材料。当前为了提高太阳电池转换效率，人们把目光瞄准了超高带隙半导体，随之而来的问题是难以找到合适的带隙更宽的材料作为窗口层。Solar cells can directly convert solar energy into electricity, which is one of the most effective ways to utilize green energy. Compared with traditional silicon solar cells, III-V semiconductor solar cells have the advantages of high conversion efficiency, strong radiation resistance, and good temperature characteristics. They are recognized as a new generation of high-performance and long-life space main power supplies. fields are widely used. With the continuous improvement of compound semiconductor growth technology (such as metal organic compound vapor phase epitaxy - MOCVD), the efficiency of III-V solar cells has been greatly improved, and the efficiency of multi-junction solar cells has exceeded 34%. How to further improve the conversion efficiency of III-V solar cells has become a current research hotspot. The introduction of the window layer forms a good passivation interface on the surface of the emission region, which increases the short-circuit current density and increases the open-circuit voltage, and the window layer needs to choose a material with a band gap larger than that of the emission region. At present, in order to improve the conversion efficiency of solar cells, people are focusing on ultra-high bandgap semiconductors, and the ensuing problem is that it is difficult to find suitable materials with wider bandgap as the window layer.

发明内容Contents of the invention

本发明的目的是提供一种异质结太阳电池，选用能与发射区材料形成II型异质结的半导体材料作为宽带隙太阳电池的窗口层，防止在界面处形成载流子输运的势垒。The object of the present invention is to provide a heterojunction solar cell, select the semiconductor material that can form a type II heterojunction with the material of the emitter region as the window layer of the wide bandgap solar cell, and prevent the formation of carrier transport potential at the interface. base.

为了达到上述目的，本发明提供了一种含有II型异质结窗口层的太阳电池，其中，该太阳电池采用能与发射区材料形成II型异质结的半导体材料作为宽带隙太阳电池的窗口层，窗口层厚度为10~50nm,发射区厚度为40~100nm。In order to achieve the above object, the present invention provides a solar cell containing a type II heterojunction window layer, wherein the solar cell uses a semiconductor material capable of forming a type II heterojunction with the emitter material as the window of the wide bandgap solar cell layer, the thickness of the window layer is 10~50nm, and the thickness of the emission area is 40~100nm.

上述的含有II型异质结窗口层的太阳电池，其中，所述的窗口层采用n型的GaAsP。In the above solar cell containing a type II heterojunction window layer, the window layer is made of n-type GaAsP.

上述的含有II型异质结窗口层的太阳电池，其中，所述的发射区采用n型AlGaInP。In the above-mentioned solar cell containing a type II heterojunction window layer, the emitter region adopts n-type AlGaInP.

本发明提供的含有II型异质结窗口层的太阳电池具有以下优点：The solar cell containing the type II heterojunction window layer provided by the present invention has the following advantages:

本发明采用的结构能解决超宽带隙太阳电池中的窗口层材料选择问题，为多结高效太阳电池的研制提高了保障。The structure adopted in the invention can solve the problem of window layer material selection in ultra-wide band gap solar cells, and improves the guarantee for the development of multi-junction high-efficiency solar cells.

附图说明Description of drawings

图1为本发明的含有II型异质结窗口层的太阳电池的实施例1结构示意图。FIG. 1 is a schematic structural diagram of Embodiment 1 of a solar cell containing a type II heterojunction window layer of the present invention.

图2和图3为I型异质结示意图。2 and 3 are schematic diagrams of type I heterojunctions.

图4为传统太阳电池中窗口层与发射区形成的I型异质结能带图。Fig. 4 is a diagram of the I-type heterojunction energy band formed by the window layer and the emitter region in a conventional solar cell.

图5为超宽带隙太阳电池中所需的II型异质结能带图。Fig. 5 is the energy band diagram of the type II heterojunction required in ultra-wide bandgap solar cells.

具体实施方式detailed description

以下结合附图对本发明的具体实施方式作进一步地说明。The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

本发明提供的含有II型异质结窗口层的太阳电池，采用能与发射区材料形成II型异质结的半导体材料作为宽带隙太阳电池的窗口层。The solar cell containing the type II heterojunction window layer provided by the invention adopts the semiconductor material capable of forming type II heterojunction with the material of the emitter region as the window layer of the wide bandgap solar cell.

窗口层采用n型的GaAsP（磷砷镓），窗口层厚度为10~50nm。The window layer adopts n-type GaAsP (Gallium Arsenic Phosphorus), and the thickness of the window layer is 10~50nm.

发射区采用n型AlGaInP（铝镓铟磷），发射区厚度为40~100nm。The emission area adopts n-type AlGaInP (aluminum gallium indium phosphide), and the thickness of the emission area is 40~100nm.

实施例1Example 1

如图1所示，以单结太阳电池为例，本发明的异质结太阳电池包括GaAs（砷化镓）缓冲层1，AlGaInP背场2，AlGaInP有源层3，AlGaInP发射区4，GaAsP窗口层5，GaAs帽子层6。窗口层厚度为40nm，发射区厚度为80nm。该结构采用低压金属有机物化学气相沉积（MOCVD）设备在n型GaAs衬底上生长。As shown in Figure 1, taking a single-junction solar cell as an example, the heterojunction solar cell of the present invention includes a GaAs (gallium arsenide) buffer layer 1, an AlGaInP back field 2, an AlGaInP active layer 3, an AlGaInP emitter region 4, a GaAsP Window layer 5, GaAs cap layer 6. The thickness of the window layer is 40nm, and the thickness of the emission region is 80nm. The structure was grown on an n-type GaAs substrate using a low-pressure metal-organic chemical vapor deposition (MOCVD) device.

传统的窗口层一般选用带隙比发射区材料带隙稍大的材料作为窗口层，一来不会吸收可利用的光照，二来对发射区形成了良好的钝化作用。少数载流子在发射区与窗口层界面处的传输主要基于量子隧穿作用。当发射区材料的带隙越来越大时，选择符合以上条件的材料作为窗口层变得越来越困难。根据组成异质结的两种材料的能带匹配情况，可以把异质结分为两类，图2和图3所示为I型，ΔEc和ΔEv的符号相反，即带隙较小材料的导带底和价带顶均位于较大带隙材料的禁带内；II型的ΔEc和ΔEv的符号相同，例如带隙较小材料的导带底位于带隙较大材料的禁带内，而价带顶位于带隙较大材料的价带之下。当前太阳电池中窗口层与发射区形成的异质结大都是I型结构，形成的能带结构如图4所示，电子在导带处通过隧穿效应传输，空穴在价带处通过扩散作用传输。当发射区材料的带隙增大时，要实现窗口层的功能就需要采用II型异质结结构了。II型异质结能带图如图5所示，从图中可以看出，在这种结构的异质结中，电子在导带处通过扩散作用传输，空穴在价带处也是通过扩散作用传输，异质结界面处不存在势垒，从而有利于载流子的输运。The traditional window layer generally uses a material with a band gap slightly larger than that of the material in the emission area as the window layer. First, it will not absorb the available light, and second, it will form a good passivation effect on the emission area. The transport of minority carriers at the interface between the emitter region and the window layer is mainly based on quantum tunneling. When the band gap of the material in the emission region becomes larger, it becomes more and more difficult to select a material that meets the above conditions as the window layer. According to the energy band matching of the two materials that make up the heterojunction, the heterojunction can be divided into two types. Figure 2 and Figure 3 show I-type, and the signs of ΔEc and ΔEv are opposite, that is, the material with a smaller band gap Both the bottom of the conduction band and the top of the valence band are located in the forbidden band of the material with a larger band gap; the signs of ΔEc and ΔEv of type II are the same, for example, the bottom of the conduction band of a material with a smaller band gap is located in the forbidden band of a material with a larger band gap, The valence band top is located below the valence band of materials with larger band gaps. Most of the heterojunctions formed by the window layer and the emitter region in current solar cells are I-type structures, and the formed energy band structure is shown in Figure 4. Electrons are transported through the tunneling effect at the conduction band, and holes are diffused at the valence band. role transmission. When the bandgap of the emitter material increases, a type II heterojunction structure is required to realize the function of the window layer. The energy band diagram of type II heterojunction is shown in Figure 5. It can be seen from the figure that in the heterojunction of this structure, electrons are transported by diffusion at the conduction band, and holes are also transported by diffusion at the valence band. For transport, there is no potential barrier at the heterojunction interface, which is conducive to the transport of carriers.

本发明提供的含有II型异质结窗口层的太阳电池，能解决超宽带隙太阳电池中的窗口层材料选择问题，为多结高效太阳电池的研制提高了保障。The solar cell containing the type II heterojunction window layer provided by the invention can solve the problem of window layer material selection in the ultra-wide bandgap solar cell, and improves the guarantee for the development of multi-junction high-efficiency solar cells.

尽管本发明的内容已经通过上述优选实施例作了详细介绍，但应当认识到上述的描述不应被认为是对本发明的限制。在本领域技术人员阅读了上述内容后，对于本发明的多种修改和替代都将是显而易见的。因此，本发明的保护范围应由所附的权利要求来限定。Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (1)

Translated fromChinese

1.一种含有II型异质结窗口层的太阳电池，其特征在于，该太阳电池采用能与发射区材料形成II型异质结的半导体材料作为宽带隙太阳电池的窗口层，即窗口层材料与发射区材料在能带上形成II型半导体异质结接触；窗口层厚度为10~50nm,发射区厚度为40~100nm；所述的窗口层采用n型的GaAsP；所述的发射区采用n型AlGaInP。1. A solar cell containing a type II heterojunction window layer, characterized in that the solar cell adopts a semiconductor material that can form a type II heterojunction with the emitter material as the window layer of a wide bandgap solar cell, i.e. the window layer The material and the material in the emission region form a type II semiconductor heterojunction contact on the energy band; the thickness of the window layer is 10-50nm, and the thickness of the emission region is 40-100nm; the window layer uses n-type GaAsP; the emission region Use n-type AlGaInP.