A solar cell and a method for manufacturing the same

Abstract

The present application relates to the technical field of solar cells, and in particular to a solar cell and a manufacturing method thereof, wherein the solar cell comprises a substrate, a base region and an emitter region in order from the bottom layer to the top layer in the growth direction; the materials of the base region and the emitter region are (Al x Ga 1‑x ) y In 1‑y As; there are multiple active layers with lattice constant a and multiple corrosion layers with lattice constant b in the base region, and a and b are not equal; the corrosion layer is a rough interface with velvet undulations formed by in-situ corrosion of the interface of the first corrosion layer by corrosion gas after the first corrosion layer is grown; the active layer and the corrosion layer are alternately distributed to form a repeating unit, and in each repeating unit, the active layer is located at the bottom of the corrosion layer. The solar cell can improve the radiation resistance, light absorption capacity and conversion efficiency of the solar cell, and can improve the final conversion efficiency of the solar cell.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a solar cell and a method for manufacturing the same. Background Art

[0002] Solar cells can directly convert solar energy into electrical energy and are the most efficient form of clean energy. III-V compound semiconductor solar cells have the highest conversion efficiency in the current material system. They also have the advantages of good high temperature resistance and strong radiation resistance. They are recognized as a new generation of high-performance and long-life space main power sources. For example, the GaInP / InGaAs / Ge lattice-matched structure triple-junction cells have been widely used in the aerospace field. However, there is high-energy charged particle radiation in the space application environment. These charged particles enter the solar cell and cause the lattice atoms to shift, forming a large number of lattice defects such as vacancies, interstitial atoms and complexes. These defects can become carrier recombination centers, resulting in a shortened lifetime of photogenerated carriers, reducing the photoelectric conversion efficiency of solar cells, and directly affecting the on-orbit service life and reliability of spacecraft. For example, multi-junction stacked solar cells are physically a series structure, and their current is limited by the sub-cell with the smallest current. In the space environment, high-energy particles can cause the In in multi-junction solar cells to undergo a series of charges. x Ga 1-x As sub-cells cause greater damage and have weaker radiation resistance. After a certain amount of radiation, In x Ga 1-x The As sub-cell often becomes a current-limiting sub-cell, thus affecting the final efficiency.

[0003] Therefore, how to improve the radiation resistance of solar cells is an urgent problem to be solved. Summary of the invention

[0004] The present application provides a solar cell and a method for manufacturing the same, which can improve the radiation resistance, light absorption capacity and conversion efficiency of the solar cell, and can improve the final conversion efficiency of the solar cell.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] In a first aspect, the present invention provides a solar cell, comprising:

[0007] From the bottom to the top, they are the substrate, the base region and the emitter region in the order of growth direction;

[0008] The materials of the base region and the emitter region are (Al x Ga 1-x ) y In 1-y As;

[0009] The base region has a plurality of active layers with a lattice constant of a and a plurality of corrosion layers with a lattice constant of b, and a and b are not equal;

[0010] The corrosion layer is a rough interface with undulating velvet surface formed by in-situ corrosion of the interface of the first corrosion layer by a corrosion gas after the first corrosion layer is grown;

[0011] The active layer and the corrosion layer are alternately distributed to form a repeating unit. In each repeating unit, the active layer is located at the bottom of the corrosion layer.

[0012] In a preferred example of the present application, it can be further configured to include:

[0013] The materials of the base region and the emitter region are (Al x Ga 1-x ) y In 1-y P or (Al x Ga 1-x ) y In 1-y As.

[0014] In a preferred example of the present application, it can be further configured to include:

[0015] The material of the substrate is Ge.

[0016] In a preferred example of the present application, it can be further configured to include:

[0017] The solar cell is a single-junction solar cell.

[0018] In a preferred example of the present application, it can be further configured to include:

[0019] The emission region includes a plurality of active layers with a lattice constant of a and a plurality of etching layers with a lattice constant of b, and a and b are not equal.

[0020] In a preferred example of the present application, it can be further configured to include:

[0021] The solar cell is one of the cells in a multi-junction stack.

[0022] In a preferred example of the present application, it can be further configured to include:

[0023] The thickness of the active layer is 5nm to 100nm.

[0024] In a preferred example of the present application, it can be further configured to include:

[0025] The thickness of the corrosion layer is 2nm to 50nm.

[0026] In a preferred example of the present application, it can be further configured to include:

[0027] The material of the substrate is GaAs or InP.

[0028] In a second aspect, the present application provides a method for manufacturing a solar cell, comprising:

[0029] Step 100: In the base region or the emitter region, an active layer with a lattice constant of a and a first etching layer with a lattice constant of b are sequentially grown from the bottom layer to the top layer along the growth direction, where a is greater than b or a is less than b;

[0030] Step 200: closing the growth reaction source, introducing a corrosive gas to in-situ corrode the first corrosive layer, and obtaining a corrosive layer;

[0031] Step 300: Repeat step 100 and step 200 until the active layer and the corrosion layer reach a preset thickness.

[0032] In summary, compared with the prior art, the technical solution provided in the embodiment of the present application has at least the following beneficial effects:

[0033] The present application provides a solar cell, which comprises a substrate, a base region and an emitter region in order from the bottom layer to the top layer in the growth direction; the materials of the base region and the emitter region are (Al x Ga 1-x ) y In 1-y As; there are multiple active layers with lattice constant a and multiple corrosion layers with lattice constant b in the base region, and a and b are not equal; the corrosion layer is formed by in-situ corrosion of the interface of the first corrosion layer by corrosion gas after the first corrosion layer is grown; the active layer and the corrosion layer are alternately distributed to form a repeating unit, and in each repeating unit, the active layer is located at the bottom of the corrosion layer. It forms a rough interface with suede undulation by in-situ corrosion of the interface of the first corrosion layer by corrosion gas, thereby increasing the light absorption area and current density of the solar cell, and further improving the radiation resistance effect by optimizing the thickness of the base region and the emission region. It improves the light absorption capacity of the active region in the solar cell, realizes a larger photocurrent, improves the solar spectrum matching of the sub-cell, and improves the conversion efficiency. The cell also improves the final conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A module diagram of a solar cell base region including an active layer and a corrosion layer provided in one embodiment of the present application.

[0035] Figure 2A schematic diagram of a repeating unit formed by an active layer and a corrosion layer of a solar cell provided in one embodiment of the present application.

[0036] Figure 3 A module diagram of an emitting region of a solar cell including an active layer and a corrosion layer provided in one embodiment of the present application.

[0037] Figure 4 A flow chart of a method for manufacturing a solar cell provided in one embodiment of the present application. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0039] In one embodiment of the present application, a solar cell is provided. Figure 1 As shown, including:

[0040] From the bottom layer to the top layer, the substrate 100, the base region 200 and the emitter region 300 are arranged in order according to the growth direction;

[0041] The materials of the base region and the emitter region are (Al x Ga 1-x ) y In 1-y As;

[0042] The base region includes a plurality of active layers 201 with a lattice constant of a and a plurality of corrosion layers 202 with a lattice constant of b, and a and b are not equal;

[0043] The corrosion layer is a rough interface with undulating velvet surface formed by in-situ corrosion of the interface of the first corrosion layer by a corrosion gas after the first corrosion layer is grown;

[0044] The active layer and the corrosion layer are alternately distributed to form a repeating unit. In each repeating unit, the active layer is located at the bottom of the corrosion layer.

[0045] In a specific implementation, the solar cell is composed of a substrate, a back electric field, a base region, an emitter region and a window layer from the bottom to the top in the growth direction. The base region and the emitter region are collectively referred to as an active region. The corrosion layer is arranged on the upper layer of the active layer along the growth direction on the back electric field. The first corrosion layer is a corrosion layer grown by a growth reaction source without in-situ corrosion. The corrosion layer is formed by in-situ corrosion of the interface of the first corrosion layer by a corrosion gas after the growth reaction source is turned off to form a rough interface. The active layer and the corrosion layer are alternately distributed, and an active layer and a corrosion layer form a repeating unit, such as Figure 2 As shown, the active region has multiple repeating units, and the active layer is from L1 to L n The corrosion layer is from E1 to E n , the repeating unit is located in the base region or the emitter region. Along the growth direction, each active layer is located at the bottom of the corrosion layer, that is, the next layer. The active layer and the corrosion layer can be a combination of p-type and n-type. For example, a p-type multi-layer active layer and a multi-layer corrosion layer can be grown first, and then an n-type multi-layer active layer and a multi-layer corrosion layer can be grown, thereby forming p-type and n-type active regions. The top layer of the solar cell along the growth direction can also include a 500nm thick n-type GaAs layer as a cap layer that forms an ohmic contact with the electrode.

[0046] In this embodiment, the first corrosion layer interface is in-situ corroded by corrosive gas to form a rough interface with velvety undulations, thereby increasing the light absorption area and current density of the solar cell, and further improving the radiation resistance effect by optimizing the thickness of the base region and the emission region. It improves the light absorption capacity of the active region in the solar cell, achieves a larger photocurrent, improves the solar spectrum matching of the sub-cell, improves the conversion efficiency, and improves the final conversion efficiency of the solar cell. Compared with the solar cell using the DBR reflective layer structure in the prior art, it has a lower manufacturing cost and a shorter manufacturing time.

[0047] In some embodiments, including:

[0048] The materials of the base region and the emitter region are (Al x Ga 1-x ) y In 1-y P or (Al x Ga 1-x ) y In 1-y As.

[0049] In some embodiments, including:

[0050] The material of the substrate is Ge.

[0051] In some embodiments, including:

[0052] The solar cell is a single-junction solar cell.

[0053] In some embodiments, including:

[0054] The emitter region 300 includes a plurality of active layers 301 with a lattice constant of a and a plurality of etching layers 302 with a lattice constant of b, wherein a and b are not equal.

[0055] When implementing it, Figure 3 As shown, there are multiple active layers 301 with a lattice constant of a and multiple corrosion layers 302 with a lattice constant of b in the emission region 300. Along the growth sequence, in each of the repeating units, the corrosion layer is located on the top of the active layer.

[0056] In some embodiments, including:

[0057] The solar cell is one of the cells in a multi-junction stack.

[0058] In some embodiments, including:

[0059] The thickness of the active layer is 5nm to 100nm.

[0060] In some embodiments, including:

[0061] The thickness of the corrosion layer is 2nm to 50nm.

[0062] In some embodiments, including:

[0063] The material of the substrate is GaAs or InP.

[0064] The present application also provides a method for manufacturing a solar cell. For manufacturing a solar cell as described in any of the above embodiments, please refer to Figure 4 As shown, the method includes:

[0065] S100: In the base region or the emitter region, an active layer with a lattice constant of a and a first etching layer with a lattice constant of b are sequentially grown from the bottom layer to the top layer along the growth direction, where a is greater than b or a is less than b;

[0066] S200: closing the growth reaction source, introducing a corrosive gas to in-situ corrode the first corrosion layer, and obtaining a corrosion layer;

[0067] S300: Repeat S100 and S200 until the active layer and the corrosion layer reach a preset thickness.

[0068] In specific implementation, the metal organic chemical vapor deposition method is referred to as MOCVD (Metal Organic Chemical Vapor Deposition), which is a method for growing semiconductor thin films on a substrate. The solar cell is grown using the MOCVD method. First, after epitaxially growing a 500nm n-type doped GaAs buffer layer on the substrate, a 100nm p-type AlGaAs back field is grown on the GaAs buffer layer. Then, p-type and n-type active regions are grown on the back field. The active region includes multiple active layers and multiple first corrosion layers. The active region material is AlGaInAs, GaInAs, AlGaAs or GaAs. A p-type active layer L1 with a thickness of 5nm to 100nm and a lattice constant of a, and a p-type first corrosion layer E1 with a thickness of 2nm to 50nm and a lattice constant of b are sequentially arranged along the growth direction. For example Figure 2 As shown, there is a lattice mismatch between the active layer L1 and the first corrosion layer E1. After the first corrosion layer E1 is grown, the growth reaction source is turned off, and the corrosion gas is introduced for in-situ corrosion to obtain the corrosion layer. The active layer L1 and the corrosion layer E1 are a repeated growth unit, and the unit is repeatedly grown until the active layer L1 is n and corrosion layer E n After the growth is completed, a p-type base region with a preset thickness is formed. Next, the n-type emitter region is grown in the same way as the p-type base region. Finally, after setting a 30nm thick n-type AlInP window layer, a 500nm thick n-type GaAs layer is grown as a cap layer to form an ohmic contact with the electrode.

[0069] In this embodiment, a method for setting the lattice mismatch of the corrosion layer is used, and the stress generated by the mismatch is conducive to in-situ corrosion, thereby improving the interface roughness and the light absorption effect. In particular, when growing a lattice mismatched solar cell, this corrosion layer setting can release the mismatch stress and reduce the dislocation density, thereby improving the crystal quality of the active area. The epitaxial structure and manufacturing method of the velvet undulating active area are used, that is, multiple active layers and multiple corrosion layers are alternately grown, and multiple repeating units are set so that the interface roughness effect along the growth direction is gradually increased, thereby gradually increasing the effective light absorption area of ​​the active layer, which is more conducive to sunlight collection. At the same time, the dislocation defects of the epitaxial are blocked or eliminated from extending upward, thereby ensuring the overall device performance described in the technical solution. The first corrosion layer interface is in-situ corroded by corrosive gas to form a rough interface with velvet undulations, thereby increasing the light absorption area and the current density, and then optimizing the thickness of the active area to improve the radiation resistance effect. Compared with the solar cell manufacturing method using the growth of the DBR reflective layer, this method has a lower manufacturing cost, a shorter manufacturing time, and improves the manufacturing efficiency of the solar cell.

[0070] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above-mentioned embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several deformations and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of this application shall be based on the attached claims.

Claims

1. A solar cell, characterized in that: include: From the bottom to the top, they are the substrate, the base region and the emitter region in the order of growth direction; The materials of the base region and the emitter region are (Al x Ga 1-x ) y In 1-y As or (Al x Ga 1-x ) y In 1-y P; The base region has a plurality of active layers with a lattice constant of a and a plurality of corrosion layers with a lattice constant of b, and a and b are not equal; The corrosion layer is a rough interface with undulating velvet surface formed by in-situ corrosion of the interface of the first corrosion layer by a corrosion gas after the first corrosion layer is grown; The active layer and the corrosion layer are alternately distributed to form a repeating unit. In each repeating unit, the active layer is located at the bottom of the corrosion layer.

2. The solar cell according to claim 1, characterized in that include: The material of the substrate is Ge.

3. The solar cell according to claim 1, characterized in that include: The solar cell is a single-junction solar cell.

4. The solar cell according to claim 1, characterized in that include: The emission region includes a plurality of active layers with a lattice constant of a and a plurality of etching layers with a lattice constant of b, and a and b are not equal.

5. The solar cell according to claim 1, characterized in that: include: The solar cell is one of the cells in a multi-junction stack.

6. The solar cell according to claim 1, characterized in that include: The thickness of the active layer is 5nm to 100nm.

7. The solar cell according to claim 6, characterized in that: include: The thickness of the corrosion layer is 2nm to 50nm.

8. The solar cell according to claim 1, characterized in that include: The material of the substrate is GaAs or InP.

9. A method for manufacturing a solar cell, characterized in that: Manufacturing a solar cell according to any one of claims 1 to 8, comprising: Step 100: In the base region or the emitter region, an active layer with a lattice constant of a and a first etching layer with a lattice constant of b are sequentially grown from the bottom layer to the top layer along the growth direction, where a is greater than b or a is less than b; Step 200: closing the growth reaction source, introducing a corrosive gas to in-situ corrode the first corrosive layer, and obtaining a corrosive layer; Step 300: Repeat step 100 and step 200 until the active layer and the corrosion layer reach a preset thickness.

Images