CN219476695U - A double-sided gallium arsenide solar cell - Google Patents

Abstract

The embodiment of the utility model relates to a double-sided gallium arsenide solar cell, whose structure from bottom to top is a back metal electrode, a first silicon carbide contact layer, a gallium arsenide solar cell body, a second silicon carbide contact layer and a front surface Metal electrodes, using highly doped polycrystalline or microcrystalline silicon carbide as the battery contact layer, using its properties of wide band gap, high conductivity, and high refractive index as transparent conductive electrodes on both sides, so as to achieve light transmission on both sides and increase the surface area. The light-transmitting area improves the photoelectric conversion efficiency, and at the same time reduces the amount of electrode metal used and reduces costs.

Description

A double-sided gallium arsenide solar cell

technical field

The utility model relates to the field of photovoltaic power generation, in particular to a double-sided gallium arsenide solar cell.

Background technique

Gallium arsenide solar cell is a solar cell based on gallium arsenide (GaAs), and its development has a history of more than 40 years. The Eg of GaAs material is 1.43eV. It is theoretically estimated that the efficiency of GaAs single-junction solar cells can reach 27%. Since the 1980s, GaAs solar cell technology has experienced from LPE to MOCVD, from homoepitaxial to heteroepitaxial , from single junction to several stages of development of multi-junction laminated structure, its development speed is increasing day by day, and its efficiency is also continuously improving.

Compared with silicon-based solar cells, GaAs solar cells have higher photoelectric conversion efficiency, stronger radiation resistance and better high temperature resistance. However, due to its high cost, it is difficult to promote in the civilian field, so the design of new materials and new structures is very important for gallium arsenide solar cells with low cost and guaranteed photoelectric conversion efficiency.

Utility model content

The purpose of this utility model is to aim at the defects of the prior art, to provide a double-sided gallium arsenide solar cell, using highly doped polycrystalline or microcrystalline silicon carbide as the cell contact layer, utilizing its wide band gap, high conductance, high refractive index Excellent performance as transparent conductive electrodes on both sides, so as to achieve light transmission on both sides, increase the surface light transmission area, improve photoelectric conversion efficiency, reduce the amount of electrode metal used, and reduce costs.

In view of this, the structure of the double-sided gallium arsenide solar cell consists of the back metal electrode, the first silicon carbide contact layer, the gallium arsenide solar cell body, the second silicon carbide contact layer and the front metal electrode from bottom to top, wherein , both the first silicon carbide contact layer and the second silicon carbide contact layer are doped polycrystalline or microcrystalline silicon carbide.

Preferably, the front metal electrode is one or more of Ti/Al, Ti, Al, Ag, Cu, and the back metal electrode is one of Ni/Cr, Ni, Ti, Al, Ag, Cu one or more species.

Preferably, both the first silicon carbide contact layer and the second silicon carbide contact layer have a thickness of 1 micrometer to 30 micrometers, and a doping concentration range of 5×10 ¹⁸ to 1×10 ²⁰ cm ⁻³ .

Preferably, the gallium arsenide solar cell body is single-junction, double-junction, triple-junction or multi-junction, and the structure of the gallium arsenide solar cell body includes a substrate layer, a buffer layer, a battery layer, a window layer and a high doped contact layer.

Preferably, the first silicon carbide contact layer is a P-type silicon carbide film layer, the second silicon carbide contact layer is an N-type silicon carbide film layer, or the first silicon carbide contact layer is an N-type silicon carbide film layer, and the second silicon carbide contact layer is an N-type silicon carbide film layer. The silicon contact layer is a P-type silicon carbide film layer.

Further preferably, the doping element of the P-type silicon carbide film layer is aluminum or boron, and the doping element of the N-type silicon carbide film layer is nitrogen.

A double-sided gallium arsenide solar cell provided by the embodiment of the utility model uses polycrystalline or microcrystalline silicon carbide material in the structure of the double-sided gallium arsenide solar cell. From the perspective of material performance, silicon carbide has high conductivity, With the advantages of wide band gap and easy control of doping concentration, heavily doped polycrystalline silicon carbide can achieve good lateral transport of carriers under the condition of wide band gap, so that it can be used as the transparent conductive electrode layer of the battery to realize the effective collection of current. Reduce the use of surface metal grid lines and provide a low-cost and high-efficiency structure for gallium arsenide solar cells. From the perspective of manufacturing, polycrystalline or microcrystalline silicon carbide can be safely, large-area, and low-cost by magnetron sputtering. Low-cost production, compatible with the production and manufacturing process of solar cells.

Description of drawings

Fig. 1 is a schematic structural diagram of a double-sided gallium arsenide solar cell provided by an embodiment of the present invention;

Fig. 2 is a flow chart of a method for preparing a double-sided gallium arsenide solar cell provided by an embodiment of the present invention.

Detailed ways

The technical solutions of the present utility model will be further described in detail through the drawings and embodiments below.

Fig. 1 is a schematic structural diagram of a double-sided gallium arsenide solar cell provided by the embodiment of the present invention. The first silicon carbide contact layer 2, the gallium arsenide solar cell body 3, the second silicon carbide contact layer 4 and the front metal electrode 5, wherein the first silicon carbide contact layer 2 and the second silicon carbide contact layer 4 are all doped polycrystalline or microcrystalline silicon carbide.

Wherein, the front metal electrode 5 can be one or more of Ti/Al, Ti, Al, Ag, Cu, and the back metal electrode 1 can be one of Ni/Cr, Ni, Ti, Al, Ag, Cu. or more.

The thicknesses of the first silicon carbide contact layer 2 and the second silicon carbide contact layer 4 are preferably 1 micron to 30 microns, and the doping concentration range is preferably 5×10 ¹⁸ to 1×10 ²⁰ cm ⁻³ .

It should be noted that the first silicon carbide contact layer can be a P-type or N-type microcrystalline or polycrystalline silicon carbide film layer, and the second silicon carbide contact layer can be an N-type or P-type microcrystalline or polycrystalline silicon carbide film layer, specifically, when the first silicon carbide contact layer is a P-type microcrystalline or polycrystalline silicon carbide film layer, and when the second silicon carbide contact layer is an N-type microcrystalline or polycrystalline silicon carbide film layer, when the first When the silicon carbide contact layer is an N-type microcrystalline or polycrystalline silicon carbide film layer, when the second silicon carbide contact layer is a P-type microcrystalline or polycrystalline silicon carbide film layer, wherein the doping element of the P-type silicon carbide film layer Including but not limited to aluminum or boron, the doping elements of the N-type silicon carbide film layer include but not limited to nitrogen.

It should be understood that silicon carbide has the advantages of wide band gap, high electrical conductivity, simple and safe preparation process, etc., and can replace surface grid wire electrodes in terms of performance and production process.

Further, the gallium arsenide solar cell body 3 can be a single-junction, double-junction, triple-junction or multi-junction gallium arsenide solar cell, and the main structure includes a substrate layer, a buffer layer, a battery layer, and a window layer from bottom to top. and highly doped contact layers.

The working process of the double-sided gallium arsenide solar cell in this embodiment is that sunlight shines on the surface of the cell, and the front side passes through the second silicon carbide contact layer 4 and shines on the gallium arsenide solar cell body 3 to generate current, and some diffusely reflected sunlight on the back side The GaAs solar cell body 3 is irradiated through the first silicon carbide contact layer 2 to generate current. The current is collected through the silicon carbide contact layers 2 and 4 on both sides, and then the current is exported through the back metal electrode 1 and the front metal electrode 5 . Compared with the existing battery, the use of surface metal grid lines is omitted, which greatly reduces the production cost of the battery. At the same time, the silicon carbide contact layer is used to transmit light on both sides, which increases the surface light transmission area and improves the photoelectric conversion efficiency.

The utility model uses polycrystalline or microcrystalline silicon carbide materials in the structure of double-sided gallium arsenide solar cells. From the perspective of material performance, silicon carbide has the advantages of high conductivity, wide band gap, and easy control of doping concentration. Polycrystalline silicon carbide can achieve good carrier lateral transport under the condition of wide band gap, so as to realize the effective collection of current as the transparent conductive electrode layer of the battery, reduce the use of surface metal grid lines, and provide gallium arsenide solar cells with A low-cost and high-efficiency structure.

The embodiment of the utility model also provides a method for preparing the above-mentioned double-sided gallium arsenide solar cell, as shown in Figure 2, the preparation method includes the following steps:

Step 101 , put the GaAs solar cell epitaxial wafer into a grinder to thin the substrate to a thickness of 100 microns to 150 microns, and polish the thinned substrate by means of chemical solution or chemical mechanical polishing.

It can be understood that the gallium arsenide solar cell epitaxial wafer can be single-junction, double-junction, triple-junction, or multi-junction. The chemical solution used here can be NH ₄ OH/H ₂ O ₂ solution, NH ₄ OH/H The volume ratio of the ₂ O ₂ solution is preferably NH ₄ OH:H ₂ O ₂ =1:8, and the thickness of the substrate is controlled to about 100 microns according to its corrosion rate.

Step 102, cleaning the polished gallium arsenide solar cell epitaxial wafer.

Specifically, wash with acetone, isopropanol, and deionized water in sequence to remove surface particles, organic pollutants, and surface metal ions, etc., then put them in HCl/H ₂ O solution for cleaning, and then rinse with deionized water to remove For surface stains, the volume ratio of the HCl/H ₂ O solution here is preferably 1:1.

Step 103 , depositing a microcrystalline or polycrystalline silicon carbide film layer on the back of the cleaned gallium arsenide solar cell epitaxial wafer to obtain a first silicon carbide contact layer.

Specifically, using a microcrystalline or polycrystalline silicon carbide target material, a microcrystalline or polycrystalline silicon carbide film layer is deposited on the back of the cleaned gallium arsenide solar cell epitaxial wafer by magnetron sputtering technology to obtain the first silicon carbide contact layer Here, the thickness of the first silicon carbide contact layer is preferably 1 micron to 30 microns, and the doping concentration range is preferably 5×10 ¹⁸ to 1×10 ²⁰ cm ⁻³ .

Step 104, depositing a microcrystalline or polycrystalline silicon carbide film layer on the front surface to obtain a second silicon carbide contact layer.

Specifically, use a microcrystalline or polycrystalline silicon carbide target material to deposit a microcrystalline or polycrystalline silicon carbide film layer on the front of the epitaxial wafer on which the first silicon carbide contact layer is deposited in step 103 above using magnetron sputtering technology to obtain a second carbonization The thickness of the silicon contact layer, the second silicon carbide contact layer here is preferably 1 micron to 10 microns, and the doping concentration range is preferably 5×10 ¹⁸ to 1×10 ²⁰ cm ⁻³ .

It should be noted that the order of step 103 and step 104 can be exchanged here, the first silicon carbide contact layer can be a P-type or N-type microcrystalline or polycrystalline silicon carbide film layer, and the second silicon carbide contact layer can be an N-type or P-type microcrystalline or polycrystalline silicon carbide film layer, specifically, when the first silicon carbide contact layer is a P-type microcrystalline or polycrystalline silicon carbide film layer, the second silicon carbide contact layer is an N-type microcrystalline or polycrystalline silicon carbide film layer. Crystalline silicon carbide film layer, when the first silicon carbide contact layer is an N-type microcrystalline or polycrystalline silicon carbide film layer, and when the second silicon carbide contact layer is a P-type microcrystalline or polycrystalline silicon carbide film layer, wherein, The doping elements of the P-type silicon carbide film layer include but not limited to aluminum or boron, and the doping elements of the N-type silicon carbide film layer include but not limited to nitrogen.

Step 105 , using a hard mask to deposit a back metal electrode on the first silicon carbide contact layer, and deposit a front metal electrode on the second silicon carbide contact layer.

Specifically, the back metal electrode and the front metal electrode are deposited by electron beam evaporation or magnetron sputtering on the first silicon carbide contact layer and the second silicon carbide contact layer using a hard mask, preferably, the front metal electrode and the back metal electrode For point metal.

Further, the front metal electrode can be one or more of Ti/Al, Ti, Al, Ag, Cu, and the back metal electrode can be one of Ni/Cr, Ni, Ti, Al, Ag, Cu. one or more species.

A method for preparing double-sided gallium arsenide solar cells provided by the embodiment of the present invention can be produced in a safe, large-area, and low-cost manner by using polycrystalline or microcrystalline silicon carbide by magnetron sputtering, and is compatible with the manufacturing process of solar cells. compatible.

In order to better understand the technical solution provided by the utility model, the specific process of the preparation method of the double-sided gallium arsenide solar cell provided by the above-mentioned embodiment of the utility model and the battery prepared by it are respectively described below with a number of specific examples. characteristics, and a comparison with a comparative example.

Example 1

This embodiment provides a method for preparing a double-sided GaAs solar cell by selecting a single-junction GaAs solar cell epitaxial wafer, and the specific structure is shown in Table 1 below:

Table 1

The method for preparing a double-sided gallium arsenide solar cell in this embodiment includes the following steps:

1. Put the single-junction gallium arsenide solar cell epitaxial wafer into a grinding machine to thin the substrate to a certain thickness, about 150 microns. Then, the substrate is polished by chemical mechanical polishing (CMP), and the thickness of the substrate is controlled to about 100 microns.

2. Clean the polished single-junction gallium arsenide solar cell epitaxial wafer: wash in acetone for 3 minutes, wash in isopropanol for 3 minutes, rinse with deionized water for 3 minutes, and then put in HCl: H ₂ Wash in a solution of O=1:1 (volume ratio) for 1 minute, then rinse with deionized water for 3 minutes to remove surface stains.

3. Use the P-type microcrystalline silicon carbide target material doped with aluminum to deposit the P-type microcrystalline silicon carbide film layer on the front of the epitaxial wafer by magnetron sputtering technology to obtain the second silicon carbide contact layer with a thickness of 5 microns and a doping concentration of The range is 5×10 ¹⁸ cm ^-3 ;

4. Use nitrogen-doped N-type microcrystalline silicon carbide target material to deposit N-type microcrystalline silicon carbide film layer on the back of the epitaxial wafer by magnetron sputtering technology to obtain the first silicon carbide contact layer with a thickness of 5 microns and a doping concentration range is 1×10 ¹⁹ cm ^-3 .

5. Use a hard mask to deposit the front metal electrode and the back metal electrode on the second silicon carbide contact layer and the first silicon carbide contact layer by electron beam evaporation or magnetron sputtering. The double-sided single-junction gallium arsenide solar cell of the film layer is prepared.

Example 2

This embodiment provides a method for preparing double-sided GaAs solar cells by selecting epitaxial wafers of two-junction GaAs solar cells. The specific structure is shown in Table 2 below:

Table 2

The method for preparing a double-sided gallium arsenide solar cell in this embodiment includes the following steps:

1. Put the two-junction gallium arsenide solar cell epitaxial wafer into a grinding machine to thin the substrate to a certain thickness, about 150 microns. Then polish the substrate with a solution of NH ₄ OH:H ₂ O ₂ =1:8 (volume ratio), and control the thickness of the substrate to about 100 microns according to its corrosion rate.

2. Clean the polished two-junction gallium arsenide solar cell epitaxial wafer: wash in acetone for 3 minutes, wash in isopropanol for 3 minutes, rinse with deionized water for 3 minutes, and then put in HCl: H ₂ Wash in a solution of O=1:1 (volume ratio) for 1 minute, then rinse with deionized water for 3 minutes to remove surface stains.

3. Use the P-type microcrystalline silicon carbide target material doped with aluminum to deposit the P-type microcrystalline silicon carbide film layer on the front of the epitaxial wafer by magnetron sputtering technology to obtain the second silicon carbide contact layer with a thickness of 5 microns and a doping concentration of The range is 5×10 ¹⁸ cm ^-3 ;

4. Use nitrogen-doped N-type microcrystalline silicon carbide target material to deposit N-type microcrystalline silicon carbide film layer on the back of the epitaxial wafer by magnetron sputtering technology to obtain the first silicon carbide contact layer with a thickness of 5 microns and a doping concentration range is 1×10 ¹⁹ cm ^-3 .

5. Use a hard mask to deposit the front metal electrode and the back metal electrode on the second silicon carbide contact layer and the first silicon carbide contact layer by electron beam evaporation or magnetron sputtering. The double-sided two-junction gallium arsenide solar cell of the film layer is prepared.

Example 3

This embodiment provides a method for preparing a double-sided GaAs solar cell by selecting a triple-junction GaAs solar cell epitaxial wafer, and the specific structure is shown in Table 3 below:

table 3

The method for preparing a double-sided gallium arsenide solar cell in this embodiment includes the following steps:

1. Put the triple-junction gallium arsenide solar cell epitaxial wafer into a grinding machine to thin the Ge substrate to a certain thickness, about 150 microns. Then polish the substrate with a solution of NH ₄ OH:H ₂ O ₂ =1:8 (volume ratio), and control the thickness of the substrate to about 100 microns according to its corrosion rate.

2. Clean the polished triple-junction gallium arsenide solar cell epitaxial wafer: wash in acetone for 3 minutes, wash in isopropanol for 3 minutes, rinse with deionized water for 3 minutes, and then put in HCl: H ₂ Wash in a solution of O=1:1 (volume ratio) for 1 minute, then rinse with deionized water for 3 minutes to remove surface stains.

3. Use nitrogen-doped N-type microcrystalline silicon carbide target material to deposit N-type microcrystalline silicon carbide film layer on the front of the epitaxial wafer by magnetron sputtering technology to obtain the second silicon carbide contact layer with a thickness of 5 microns and a doping concentration of The range is 1×10 ¹⁹ cm ^-3 ;

4. Use aluminum-doped P-type microcrystalline silicon carbide target material to deposit P-type microcrystalline silicon carbide film layer on the back of the epitaxial wafer by magnetron sputtering technology to obtain the first silicon carbide contact layer with a thickness of 5 microns and a doping concentration range is 5×10 ¹⁸ cm ^-3 .

5. Use a hard mask to deposit the front metal electrode and the back metal electrode on the second silicon carbide contact layer and the first silicon carbide contact layer by electron beam evaporation or magnetron sputtering. The double-sided triple-junction gallium arsenide solar cell of the film layer is prepared.

Comparative example 1

The gallium arsenide solar cell in Comparative Example 1 is a single-sided cell. The method is to first form a layer of SiO ₂ /TiO ₂ anti-reflection film on the front of the cell epitaxial wafer shown in Table 1, and then evaporate the metal front grid electrode on it. , and finally evaporate the metal electrode on the entire back surface to obtain a single-sided single-junction gallium arsenide solar cell.

Comparative example 2

The gallium arsenide solar cell in Comparative Example 2 is a single-sided cell. The method is to first make a layer of SiO ₂ /TiO ₂ anti-reflection film on the front of the cell epitaxial wafer shown in Table 2, and then evaporate the metal front grid electrode on it. , and finally vaporize the metal electrode on the back surface to obtain a single-sided double-junction gallium arsenide solar cell.

Comparative example 3

The gallium arsenide solar cell in Comparative Example 3 is a single-sided cell. The method is to first make a layer of SiO ₂ /TiO ₂ anti-reflection film on the front of the cell epitaxial wafer shown in Table 3, and then evaporate the metal front grid electrode on it. , and finally evaporate the metal electrodes on the entire back surface to obtain a single-sided triple-junction gallium arsenide solar cell.

Select the cells of 1 square centimeter in the solar cells obtained in the above-mentioned embodiments 1, 2, 3 and comparative examples 1, 2, 3 to carry out multiple tests under a double solar simulator, and the test results are as follows:

It can be seen from the test results that the Voc and FF indicators of the double-sided GaAs solar cells of each embodiment are comparable to their corresponding counterparts, and the Isc, Pm and Eff indicators are higher than those of the cells in the comparative example.

A double-sided gallium arsenide solar cell provided by the embodiment of the utility model uses highly doped polycrystalline or microcrystalline silicon carbide as the battery contact layer, and utilizes its wide bandgap, high conductance, and high refractive index performance as the transparent conductive layer on both sides. Electrodes, so as to achieve light transmission on both sides, increase the surface light transmission area, improve photoelectric conversion efficiency, reduce the amount of electrode metal used, and reduce costs.

In the description of the present utility model, it should be understood that the orientations or positional relationships indicated by the terms "up", "down", "left", "right", "front", "rear" etc. are based on those shown in the accompanying drawings. Orientation or positional relationship is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the referred device or unit must have a specific orientation, be constructed and operated in a specific orientation, therefore, it cannot be understood as a limits.

In the description in this specification, descriptions of the terms "a specific embodiment", "some embodiments", "one embodiment" and the like mean that specific features, structures, materials or characteristics described in connection with the embodiment or example include In at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present utility model in detail. Within the protection scope of the utility model, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the utility model shall be included in the protection scope of the utility model.

Claims (5)

1. The double-sided gallium arsenide solar cell is characterized in that the double-sided gallium arsenide solar cell structure sequentially comprises a back metal electrode, a first silicon carbide contact layer, a gallium arsenide solar cell body, a second silicon carbide contact layer and a front metal electrode from bottom to top, wherein the first silicon carbide contact layer and the second silicon carbide contact layer are doped polycrystalline or microcrystalline silicon carbide.

2. The dual sided gallium arsenide solar cell of claim 1, wherein the first silicon carbide contact layer and the second silicon carbide contact layer each have a thickness of 1 micron to 30 microns.

3. The double sided gallium arsenide solar cell of claim 1, wherein the gallium arsenide solar cell body is single junction, double junction, triple junction or multi junction, and the gallium arsenide solar cell body structure comprises a substrate layer, a buffer layer, a cell layer, a window layer and a highly doped contact layer from bottom to top.

4. The dual sided gallium arsenide solar cell of claim 1, wherein the first silicon carbide contact layer is a P-type silicon carbide film, the second silicon carbide contact layer is an N-type silicon carbide film, or wherein the first silicon carbide contact layer is an N-type silicon carbide film, and the second silicon carbide contact layer is a P-type silicon carbide film.

5. The dual sided gallium arsenide solar cell of claim 4, wherein the doping element of the P-type silicon carbide film is aluminum or boron and the doping element of the N-type silicon carbide film is nitrogen.