A three-junction solar cell epitaxial structure for space satellite and a manufacturing method thereof

Abstract

This invention discloses a triple-junction solar cell epitaxial structure suitable for aerospace satellites and its manufacturing method. A Ge substrate is used as the bottom cell, and then an InGaAs middle cell and a GaInP top cell are sequentially grown on the Ge substrate using MOCVD. Both the InGaAs middle cell and the GaInP top cell include an emitter region and a window layer. After growing the emitter region of the InGaAs middle cell and / or the GaInP top cell, SiH4 is introduced into the MOCVD reaction chamber at a rate of 100-200 sccm for 50-100 s. The window layer is then grown. This method reduces interfacial recombination at the window layer, improving the photoelectric conversion efficiency and yield for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, and specifically relates to a triple-junction solar cell epitaxial structure suitable for aerospace satellites and its manufacturing method. Background Technology

[0002] GaInP / InGaAs / Ge triple-junction solar cells are core components in space satellites, deep space probes, and ground-based high-concentration photovoltaic systems due to their wide spectral response coverage and high photoelectric conversion efficiency (over 35% in laboratory settings). The window layer, a key functional layer above the cell's emitter region, plays a crucial role in providing high light transmittance, forming a conduction band barrier to prevent minority carrier surface recombination, and reducing surface state density, thereby increasing the cell's open-circuit voltage (Voc) and short-circuit current (Jsc).

[0003] Currently, the window layer of GaInP top cells and InGaAs middle cells mainly uses wide-bandgap materials such as AlInP and is prepared by metal-organic chemical vapor deposition (MOCVD) epitaxial growth technology. However, the interface quality between the window layer and the emitter region (GaInP, InGaAs) directly determines the carrier collection efficiency of the cell, and severe interfacial recombination has become a core bottleneck restricting further improvement of cell performance.

[0004] When using MOCVD epitaxial growth technology on the window layer, the following drawbacks exist: 1. Interface impurities and oxide layer residues: During the MOCVD growth process, after the emitter region is grown, carbon impurities and oxide layers are easily left at the interface. These impurities will form deep-level recombination centers, which will accelerate the nonradiative recombination of charge carriers. 2. High interface state density: There are a large number of dangling bonds at the interface between the window layer and the emitter region, which are not effectively passivated, resulting in a significant increase in the probability of carriers being trapped and recombinized. 3. Poor lattice matching: There is a lattice mismatch (mismatch degree > 0.2%) between the AlInP or AlGaInP window layer and the GaInP or InGaAs emitter region, which easily introduces defects such as dislocations and stacking faults, further aggravating interface recombination; 4. Band abrupt changes lead to obstruction of carrier transport: Traditional window layers have a compositional abrupt change structure, forming sharp band barrier peaks between them and the emitter layer. Carriers are prone to accumulate and be trapped at the interface, thereby reducing carrier collection efficiency. 5. Poor quality of interface nucleation: High-temperature nucleation easily leads to segregation of interface components and island growth, introducing a large number of interface defects and increasing the number of composite centers.

[0005] Although existing window layer MOCVD growth processes employ some interface optimization techniques, these techniques are singular, simple, and fragmented, failing to fundamentally solve the problem of interface composite. Summary of the Invention

[0006] The purpose of this invention is to provide a triple-junction solar cell epitaxial structure suitable for aerospace satellites and its manufacturing method, which fundamentally reduces window layer interface recombination and improves the photoelectric conversion efficiency and mass production yield of the cell.

[0007] To achieve the above objectives, the present invention provides a method for manufacturing a triple-junction solar cell epitaxial structure suitable for aerospace satellites, comprising: A Ge substrate is provided as the bottom cell. An InGaAs middle cell and a GaInP top cell are sequentially grown on the Ge substrate using the MOCVD method. Both the InGaAs middle cell and the GaInP top cell contain an emitter region and a window layer. After growing the emitter region of the InGaAs middle cell and / or the GaInP top cell, SiH4 is introduced into the MOCVD reaction chamber at a rate of 100-200 sccm for 50-100 s. Then, the window layer is grown.

[0008] Furthermore, after growing the emitter region of the InGaAs solar cell, SiH4 is introduced. A GaInP transition layer is provided between the emitter region and the window layer of the InGaAs solar cell. The GaInP transition layer is Ga... x5 In 1-x5 P is a transition layer, where 0.5 ≤ x5 ≤ 0.6.

[0009] Furthermore, the window layer of the InGaAs cell is an AlInP window layer, which includes an AlInP graded layer and a high-Al composition window layer. The AlInP graded layer is Al... x6 In 1-x6 P layer, the high Al composition window layer is Al x7 In 1-x7 Layer P, where x6 linearly changes from 0.5 to 0.6, and 0.6≤x7≤0.7.

[0010] Furthermore, during the growth of InGaAs solar cells, in the initial 2nm-5nm stage before the growth of the GaInP transition layer and AlInP window layer, a low-temperature nucleation process is adopted to reduce the MOCVD reaction chamber temperature by 30℃-50℃ and the growth rate to 0.1nm / s-0.2nm / s.

[0011] Furthermore, the GaInP transition layer has a growth thickness of 5nm-10nm, and the doping element is N-type Si with a doping amount of 3E. 18 cm -3 Up to 5E 18 cm -3The AlInP graded layer has a growth thickness of 30nm-50nm, and the doping element is N-type Si with a doping amount of 1E. 18 cm -3 To 3E 18 cm -3 The growth thickness of the high Al composition window layer is 10nm-20nm, and the doping elements and doping amounts are the same as those of the AlInP graded layer.

[0012] Furthermore, after growing the emitter region of the GaInP top cell, SiH4 is introduced. The window layer structure of the GaInP top cell is the same as that of the InGaAs cell, both including an AlInP gradient layer and a high Al content window layer. The difference is that the growth thickness of the AlInP gradient layer and the high Al content window layer of the GaInP top cell are 20nm-30nm and 10nm-20nm, respectively.

[0013] Furthermore, the emitter region of the InGaAs battery is an InGaAs emitter region, and the InGaAs emitter region is In... x4 Ga 1-x4 The InGaAs emitter region has a growth thickness of 50nm-200nm, where x4=0.01, and is doped with N-type Si at a doping level of 1E. 18 cm -3 To 3E 18 cm -3 .

[0014] Furthermore, the emitter region of the GaInP top-mounted solar cell is a GaInP emitter region, and the GaInP emitter region is Ga... x3 In 1- x3 In the P-emitter region, where 0.4 ≤ x³ ≤ 0.6, the growth thickness of the GaInP emitter region is 50 nm-150 nm, and the dopant element is N-type Si with a doping amount of 1E. 18 cm -3 Up to 2E 18 cm -3 .

[0015] Furthermore, a first tunnel junction is grown between the Ge substrate and the InGaAs in-cell, and the growth of the InGaAs in-cell includes: a DBR layer, an AlGaAs back surface field layer, an InGaAs base region, an InGaAs emitter region, a GaInP transition layer, and an AlInP window layer grown sequentially on the first tunnel junction; a second tunnel junction is grown between the InGaAs in-cell and the GaInP top cell, and the growth of the GaInP top cell includes: an AlGaInP back surface field layer, a GaInP base region, a GaInP emitter region, and an AlInP window layer grown sequentially on the second tunnel junction.

[0016] This application also provides a triple-junction solar cell epitaxial structure suitable for aerospace satellites, which is manufactured by any of the manufacturing methods described above.

[0017] After adopting the above solution, the beneficial effects of the present invention are as follows: 1. After the emitter region is grown, SiH4 is introduced at a rate of 100-200 sccm for 50-100 s. Then, a window layer is grown. During this process, Si atoms, as shallow donor impurities, can fill the interface trap energy levels, passivate the interface states, and reduce the interface state density. At the same time, using Si atoms for atomic-level ultrathin doping can avoid the concentration of the interface electric field caused by doping abrupt changes, reduce carrier scattering and recombination, and significantly improve the interface carrier transport efficiency.

[0018] 2. In this application, a GaInP transition layer is provided between the emitter region and the window layer of the InGaAs cell. The GaInP transition layer is Ga... x5 In 1-x5 The GaInP transition layer, where 0.5≤x5≤0.6, serves as a lattice buffer layer between the window layer and the emitter region. It simultaneously prevents Al atoms in the AlInP window layer from reacting directly with As atoms in the InGaAs emitter region, thus avoiding the formation of deep-level defects in AlInAsP. At the same time, it achieves a gradual lattice transition between the window layer and the emitter region, initially reducing lattice mismatch.

[0019] 3. The window layer of this application (the window layer of the InGaAs cell and / or the GaInP top cell) consists of an AlInP graded layer and a high Al composition window layer. The Al composition of the AlInP graded layer linearly changes from 0.5 to 0.6, while the Al composition of the high Al composition window layer is between 0.6 and 0.7 (including the endpoint values). The AlInP graded layer realizes a continuous and smooth transition of the energy band between the window layer and the emitter region, eliminates the barrier spike of the traditional abrupt junction, reduces the carrier transport barrier, and can also slowly release the stress between the high Al composition window layer and the emitter region to prevent the generation of mismatch lines. The high Al composition window layer increases the barrier height, effectively restricts the diffusion of carriers, and improves the degradation of the photoelectric conversion efficiency of the solar cell at high temperatures.

[0020] 4. In the initial growth stage (first 2nm~5nm) of the GaInP transition layer and AlInP window layer during the growth of InGaAs solar cells in this application, a low-temperature nucleation process is adopted to reduce the reaction chamber temperature by 30℃-50℃ and the growth rate to 0.1nm / s-0.2nm / s, thereby achieving two-dimensional flat nucleation, avoiding island growth and component segregation caused by high-temperature nucleation, and reducing the generation of interface defects (dislocations, stacking faults); at the same time, low-temperature nucleation can reduce the atomic diffusion rate, ensure component uniformity, improve the interface crystallization quality, and further reduce the number of interface recombination centers. Attached Figure Description

[0021] Figure 1 This is an epitaxial structure diagram of the solar cell of the present invention.

[0022] Figure 2 This is a flowchart of the manufacturing method of the present invention.

[0023] Label Explanation: 1. Ge substrate; 2. GaInP nucleation layer; 3. GaAs buffer layer; 4. First tunnel junction; 5. DBR layer; 6. AlGaAs back surface layer; 7. InGaAs base region; 8. InGaAs emitter region; 9. GaInP transition layer; 10. Al x6 In 1-x6 P layer; 11, Al x7 In 1-x7 12. Second tunnel junction; 13. AlGaInP back field layer; 14. GaInP base region; 15. GaInP emitter region; 16. Al x4 In 1-x4 P layer; 17, Al x5 In 1-x5 P layer; 18. GaAs ohmic contact layer. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application, and the range values ​​mentioned in this application all include endpoint values.

[0025] Key references Figure 1 This invention provides a method for manufacturing a triple-junction solar cell epitaxial structure suitable for aerospace satellites, using MOCVD (organic chemical vapor deposition) for growth. The manufacturing method specifically includes the following steps: S1. A Ge substrate 1 is provided as the bottom cell. The Ge substrate is selected as a 9-degree P-type Ge substrate. N-type phosphorus diffusion is performed on the 9-degree P-type Ge substrate to diffuse the outermost Ge into N-type, thereby obtaining the PN junction of the bottom cell. Then, a GaInP nucleation layer 2 and a GaAs buffer layer 3 that match the Ge lattice are grown sequentially, with growth thicknesses of 20nm-50nm and 200nm-300nm, respectively. These two layers serve as window layers of the bottom cell and also as connection layers between the Ge substrate and the subsequent epitaxial layers, thereby completing the fabrication of the bottom cell.

[0026] S2. A first tunneling junction 4 is grown on the bottom cell, specifically on the GaAs buffer layer 3. The first tunneling junction 4 is composed of heavily N-type doped GaAs and heavily P-type doped GaAs, with a growth thickness of 10 nm-30 nm. The heavily N-type doped GaAs is doped with Te, with a doping amount of 1E. 19 cm -3 Up to 2E 19 cm -3 P-type heavily doped GaAs with C doping at a doping level of 1E 20 cm -3 Up to 2E 20 cm -3 The first tunnel junction 4 utilizes the tunneling effect to connect the bottom cell to the subsequently grown InGaAs middle cell.

[0027] S3. Growing an InGaAs solar cell on the first tunnel junction 4, the InGaAs solar cell comprising a DBR layer 5 (distributed Bragg reflector layer), an AlGaAs back field layer 6, an InGaAs base region 7, an InGaAs emitter region 8, a GaInP transition layer 9, and an AlInP window layer grown sequentially along a direction away from the first tunnel junction 4, specifically including the following steps: S3.1. A DBR layer 5 is grown on the first tunnel junction 4. The DBR layer 5 is a mirror structure, which is an adjustable multilayer structure composed of two optical materials, specifically made of In...x1 Ga 1-x1 As、Al x2 Ga 1-x2 As is formed by alternating growth of two materials, where x1 = 0.01, 0.6 ≤ x2 ≤ 1, and the optical thickness of a single layer is one-quarter of the center wavelength of the reflection spectrum, which is 850 nm-900 nm. The number of alternation pairs in the DBR layer 5 is 8-25, and the doping element is p-type Zn with a doping amount of 1E. 18 cm -3 Up to 4E 18 cm -3 .

[0028] S3.2. An AlGaAs back field layer 6 is grown on the DBR layer 5. The growth thickness of the AlGaAs back field layer 6 is 80nm-100nm, and the Al component accounts for 60%-90%.

[0029] S3.3. An InGaAs base region 7 is grown on the AlGaAs backfield layer 6, wherein the InGaAs base region 7 is specifically In... x3 Ga 1-x3 The InGaAs base region has x3 = 0.01, and the growth thickness of the InGaAs base region 7 is 2000 nm-3000 nm. The doping element is the p-type dopant Zn, and the doping amount is 5E. 17 cm -3 Gradient to 1E 16 cm -3 .

[0030] S3.4. An InGaAs emitter region 8 is grown on the InGaAs base region 7. This InGaAs emitter region 8 is the emitter region of the InGaAs battery. The InGaAs emitter region 8 is an InGaAs base region. x4 Ga 1-x4 In the As emitter region, x4 = 0.01, the growth thickness of the InGaAs emitter region 8 is 50nm-200nm, and the doping element is N-type Si with a doping amount of 1E. 18 cm -3 To 3E 18 cm -3 .

[0031] S3.5 After growing the InGaAs emitter region 8, SiH4 is introduced into the MOCVD reaction chamber at a rate of 100-200 sccm for 50-100 s. That is, in this application, SiH4 is introduced between the InGaAs emitter region 8 and the AlInP window layer. Si atoms, as shallow donor impurities, can fill the interface trap energy levels, passivate interface states, and reduce the interface state density. Simultaneously, using Si atoms for atomic-level ultrathin doping avoids interface electric field concentration caused by abrupt doping changes, reduces carrier scattering and recombination, and significantly improves interface carrier transport efficiency.

[0032] S3.6 After introducing SiH4, a GaInP transition layer 9 is then grown, wherein the GaInP transition layer 9 is Ga x5 In 1-x5 The GaInP transition layer 9 has a growth thickness of 5nm-10nm, where 0.5≤x5≤0.6, and is doped with N-type Si at a doping concentration of 3E. 18 cm -3 Up to 5E 18 cm -3 The GaInP transition layer 9 serves as a lattice buffer layer between the AlInP window layer and the InGaAs emitter region 8. It simultaneously prevents the Al atoms in the AlInP window layer from reacting directly with the As atoms in the InGaAs emitter region 8, thus avoiding the formation of deep-level defects in AlInAsP. At the same time, it achieves a gradual lattice transition between the window layer and the emitter region, initially reducing lattice mismatch.

[0033] S3.7. An AlInP window layer is grown on the GaInP transition layer 9. This AlInP window layer is the window layer of the InGaAs cell. The AlInP window layer includes a sequentially grown AlInP graded layer and a high-Al content window layer. The AlInP graded layer is composed of Al... x6 In 1-x6 P layer 10, the high Al composition window layer is Al x7 In 1-x7 Layer P11, wherein x6 linearly changes from 0.5 to 0.6, 0.6≤x7≤0.7, and Al x6 In 1-x6 The P-layer 10 has a growth thickness of 30nm-50nm, and is doped with N-type Si with a doping amount of 1E. 18 cm -3 To 3E 18 cm -3 The Al x7 In 1-x7 The growth thickness of the P-layer 11 is 10nm-20nm, and the doping elements and doping amounts are similar to those of Al. x6 In 1-x6The same applies to layer 10. The AlInP graded layer achieves a smooth and continuous transition of the energy bands between the window layer and the emitter region, eliminating the barrier spikes of traditional abrupt junctions, reducing the carrier transport barrier, and slowly releasing the stress between the high-Al composition window layer and the emitter region to prevent the formation of mismatch lines. Meanwhile, the high-Al composition window layer increases the barrier height, effectively limiting carrier diffusion and improving the degradation of solar cell photoelectric conversion efficiency at high temperatures.

[0034] Preferably, in the initial stage of growing the GaInP transition layer 9 and the AlInP window layer, 2nm-5nm before growth, a low-temperature nucleation process is adopted to reduce the MOCVD reaction chamber temperature by 30℃-50℃ and the growth rate to 0.1nm / s-0.2nm / s. This can achieve two-dimensional flat nucleation, avoid island growth and component segregation caused by high-temperature nucleation, and reduce the generation of interface defects (dislocations, stacking faults). At the same time, low-temperature nucleation can reduce the atomic diffusion rate, ensure component uniformity, improve the interface crystallization quality, and further reduce the number of interface recombination centers.

[0035] S4. A second tunnel junction 12 is grown on the InGaAs cell, i.e., on Al. x7 In 1-x7 A second tunnel junction 12 is grown on the P-layer 11, and the second tunnel junction 12 is made of N-type heavily doped Ga. x In 1-x P and P-type heavily doped Al y Ga 1-y The composition is As, and the growth thickness is 10nm-30nm. Among them, N-type heavily doped Ga x In 1-x P-doped Si, with a doping level of 1E 19 cm -3 Up to 2E 19 cm -3 And 0.5≤x≤0.6; P-type heavily doped Al y Ga 1-y As doped with C, the doping amount is 1E. 20 cm -3 Up to 2E 20 cm -3 And 0.4≤y≤0.6. The second tunnel junction 12 utilizes the tunneling effect to connect the InGaAs cell to the subsequently grown GaInP top cell.

[0036] S5. Growing a GaInP top cell in the second tunnel junction 12, the GaInP top cell comprising an AlGaInP back field layer 13, a GaInP base region 14, a GaInP emitter region 15, and an AlInP window layer grown sequentially along a direction away from the second tunnel junction 12, specifically including the following steps: S5.1, An AlGaInP back field layer 13 is grown on the second tunnel junction 12, wherein the AlGaInP back field layer 13 is specifically composed of (Al x1 Ga 1-x1 ) y1 In 1-y1 The AlGaInP back field layer 13 has a growth thickness of 50nm-100nm, where 0.5≤x1≤0.8 and y1=0.5. The dopant element is p-type Zn, and the doping concentration is 1E. 18 cm -3 Up to 4E 18 cm -3 .

[0037] S5.2. A GaInP base region 14 is grown on the AlGaInP back field layer 13, wherein the GaInP base region 14 is specifically Ga... x2 In 1- x2 In the P-based region, where 0.4 ≤ x² ≤ 0.6, the growth thickness of GaInP-based region 14 is 600 nm-800 nm, and the doping element is the p-type dopant Zn, with a doping amount ranging from 1E. 18 cm -3 Gradient to 1E 17 cm -3 .

[0038] S5.3. A GaInP emitter region 15 is grown on the GaInP base region 14. This GaInP emitter region 15 is the emitter region of the GaInP top cell. Specifically, the GaInP emitter region 15 is Ga... x3 In 1-x3 In the P-emitter region, where 0.4 ≤ x3 ≤ 0.6, the growth thickness of the GaInP-emitter region 15 is 50 nm-150 nm, and the doping element is N-type Si with a doping amount of 1E. 18 cm -3 To 2EE 18 cm -3 .

[0039] S5.4 After growing the GaInP emitter region 15, SiH4 is introduced into the MOCVD reaction chamber at a rate of 100-200 sccm for 50-100 s. This means that SiH4 is also introduced between the emitter region and the window layer of the GaInP top cell, further passivating the interface states, reducing the interface state density, decreasing carrier scattering and recombination, and improving the interface carrier transport efficiency.

[0040] S5.5 After introducing SiH4, the window layer of the GaInP top cell is then grown. The window layer structure of the GaInP top cell is the same as that of the InGaAs cell, both including an AlInP graded layer and a high-Al content window layer. Specifically, the AlInP graded layer of the GaInP top cell is Al... x4 In 1-x4 P-layer 16, the high Al composition window layer of the GaInP top cell is Al x5 In 1-x5 Layer P17, where x4 linearly changes from 0.5 to 0.6, 0.6 ≤ x5 ≤ 0.7, and Al x4 In 1-x4 The P-layer 16 has a growth thickness of 20nm-30nm, and is doped with N-type Si with a doping amount of 1E. 18 cm -3 To 3E 18 cm -3 The Al x5 In 1-x5 The growth thickness of the P-layer 17 is 10nm-20nm, and the doping elements and doping amounts are similar to those of Al. x4 In 1-x4 The P-layer 16 is the same. That is, the window layer structure of the GaInP top cell is the same as that of the InGaAs cell. The only difference is that the thickness of the AlInP graded layer in the GaInP top cell is 20nm-30nm. The two have the same function, but the high Al content window layer of the GaInP top cell also increases the material band gap, reduces the absorption of short-wavelength light intensity by the window layer of the GaInP top cell, effectively increases the absorption of short-wavelength light intensity by the solar cell, and increases the conversion efficiency of the solar cell.

[0041] S6. Grow a GaAs ohmic contact layer 18 on the GaInP top cell, i.e., on Al x5 In 1-x5 A GaAs ohmic contact layer 18 is grown on the P-layer 17. The GaAs ohmic contact layer 18 has a thickness of 500 nm-800 nm and is doped with N-type Si with a doping amount of 3E. 18 cm -3 Up to 5E 18 cm -3 .

[0042] like Figure 1As shown, this application also provides a triple-junction solar cell epitaxial structure suitable for aerospace satellites, manufactured by the above-described manufacturing method, comprising, from bottom to top, a Ge substrate 1, a GaInP nucleation layer 2, a GaAs buffer layer 3, a first tunnel junction 4, a DBR layer 5, an AlGaAs back field layer 6, an InGaAs base region 7, an InGaAs emitter region 8, a GaInP transition layer 9, an AlInP window layer, a second tunnel junction 12, an AlGaInP back field layer 13, a GaInP base region 14, a GaInP emitter region 15, an AlInP window layer, and a GaAs ohmic contact layer 18.

[0043] Wherein, the GaInP transition layer 9 is Ga x5 In 1-x5 A P-transition layer, wherein 0.5 ≤ x5 ≤ 0.6, has a growth thickness of 5 nm-10 nm, and is doped with N-type Si with a doping amount of 3E. 18 cm -3 Up to 5E 18 cm -3 .

[0044] The AlInP window layer of the InGaAs battery comprises an AlInP graded layer and a high-Al content window layer, wherein the AlInP graded layer is Al x6 In 1-x6 P layer 10, the high Al composition window layer is Al x7 In 1-x7 Layer P11, wherein x6 linearly changes from 0.5 to 0.6, 0.6≤x7≤0.7, and Al x6 In 1-x6 The P-layer 10 has a growth thickness of 30nm-50nm, and is doped with N-type Si with a doping amount of 1E. 18 cm -3 To 3E 18 cm -3 The Al x7 In 1-x7 The growth thickness of the P-layer 11 is 10nm-20nm, and the doping elements and doping amounts are similar to those of Al. x6 In 1-x6 The same applies to layer 10 of P.

[0045] The AlInP window layer structure of the GaInP top-cell solar cell is the same as that of the InGaAs solar cell, both including an AlInP graded layer and a high-Al content window layer. Specifically, the AlInP graded layer of the GaInP top-cell solar cell is Al... x4 In 1-x4 P-layer 16, the high Al composition window layer of the GaInP top cell is Al x5 In 1-x5Layer P17, where x4 linearly changes from 0.5 to 0.6, 0.6 ≤ x5 ≤ 0.7, and Al x4 In 1-x4 The P-layer 16 has a growth thickness of 20nm-30nm, and is doped with N-type Si with a doping amount of 1E. 18 cm -3 To 3E 18 cm -3 The Al x5 In 1-x5 The growth thickness of the P layer 17 is 10nm-20nm, and the doping elements and doping amounts are the same as those of the AlInP graded layer.

[0046] It is worth noting that, as shown in the accompanying drawings of this application, the Ge substrate 1, GaInP nucleation layer 2, GaAs buffer layer 3, first tunnel junction 4, DBR layer 5, AlGaAs back field layer 6, InGaAs base region 7, InGaAs emitter region 8, GaInP transition layer 9, and Al... x6 In 1-x6 P layer 10, Al x7 In 1-x7 11. P-layer; 12. Second tunnel junction; 13. AlGaInP back field layer; 14. GaInP base region; 15. GaInP emitter region; 16. Al x4 In 1-x4 P layer 16, Al x5 In 1-x5 The thicknesses of the P-layer 17 and the GaAs ohmic contact layer 18 are merely examples and do not represent their actual thicknesses. Furthermore, the thicknesses of the Ge substrate 1, GaInP nucleation layer 2, GaAs buffer layer 3, first tunnel junction 4, DBR layer 5, AlGaAs back surface layer 6, InGaAs base region 7, InGaAs emitter region 8, GaInP transition layer 9, and Al... x6 In 1-x6 P layer 10, Al x7 In 1-x7 11. P-layer; 12. Second tunnel junction; 13. AlGaInP back field layer; 14. GaInP base region; 15. GaInP emitter region; 16. Al x4 In 1-x4 P layer 16, Al x5 In 1-x5 The actual ratio between the P-layer 17 and the GaAs ohmic contact layer 18 is not as shown in the attached figures and is for reference only.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for manufacturing a triple-junction solar cell epitaxial structure suitable for aerospace satellites, characterized in that, include: A Ge substrate is provided as the bottom cell. An InGaAs middle cell and a GaInP top cell are sequentially grown on the Ge substrate using the MOCVD method. Both the InGaAs middle cell and the GaInP top cell contain an emitter region and a window layer. After growing the emitter region of the InGaAs middle cell and / or the GaInP top cell, SiH4 is introduced into the MOCVD reaction chamber at a rate of 100-200 sccm for 50-100 s. Then, the window layer is grown.

2. The epitaxial structure of a triple-junction solar cell as described in claim 1, characterized in that: After growing the emitter region of the InGaAs solar cell, SiH4 is introduced. A GaInP transition layer is provided between the emitter region and the window layer of the InGaAs solar cell. The GaInP transition layer is Ga... x5 In 1-x5 P is a transition layer, where 0.5 ≤ x5 ≤ 0.

6.

3. The manufacturing method of a triple-junction solar cell epitaxial structure suitable for aerospace satellites as described in claim 2, characterized in that: The window layer of the InGaAs cell is an AlInP window layer, which includes an AlInP graded layer and a high-Al content window layer. The AlInP graded layer is Al... x6 In 1-x6 P layer, the high Al composition window layer is Al x7 In 1-x7 Layer P, where x6 linearly changes from 0.5 to 0.6, and 0.6≤x7≤0.

7.

4. The manufacturing method of a triple-junction solar cell epitaxial structure suitable for aerospace satellites as described in claim 3, characterized in that: In the process of growing InGaAs solar cells, during the initial stage of growing the GaInP transition layer and AlInP window layer (2nm-5nm), a low-temperature nucleation process is adopted to reduce the MOCVD reaction chamber temperature by 30℃-50℃ and the growth rate to 0.1nm / s-0.2nm / s.

5. The epitaxial structure of a triple-junction solar cell as described in claim 3, characterized in that: The GaInP transition layer has a growth thickness of 5nm-10nm, and the doping element is N-type Si with a doping amount of 3E. 18 cm -3 Up to 5E 18 cm -3 The AlInP graded layer has a growth thickness of 30nm-50nm, and the doping element is N-type Si with a doping amount of 1E. 18 cm -3 To 3E 18 cm -3 The growth thickness of the high Al composition window layer is 10nm-20nm, and the doping elements and doping amounts are the same as those of the AlInP graded layer.

6. The method for manufacturing a triple-junction solar cell epitaxial structure suitable for aerospace satellites as described in claim 3, characterized in that: After growing the emitter region of the GaInP top cell, SiH4 is introduced. The window layer structure of the GaInP top cell is the same as that of the InGaAs cell, both including an AlInP gradient layer and a high Al content window layer. The difference is that the growth thickness of the AlInP gradient layer and the high Al content window layer of the GaInP top cell are 20nm-30nm and 10nm-20nm, respectively.

7. The method for manufacturing a triple-junction solar cell epitaxial structure suitable for aerospace satellites as described in claim 1, characterized in that: The emitter region of the InGaAs battery is an InGaAs emitter region, and the InGaAs emitter region is In... x4 Ga 1-x4 The InGaAs emitter region has a growth thickness of 50nm-200nm, where x4=0.01, and is doped with N-type Si at a doping level of 1E. 18 cm -3 To 3E 18 cm -3 .

8. The manufacturing method of a triple-junction solar cell epitaxial structure suitable for aerospace satellites as described in claim 1, characterized in that: The emitter region of the GaInP top-mounted solar cell is a GaInP emitter region, and the GaInP emitter region is Ga... x3 In 1-x3 In the P-emitter region, where 0.4 ≤ x³ ≤ 0.6, the growth thickness of the GaInP emitter region is 50 nm-150 nm, and the dopant element is N-type Si with a doping amount of 1E. 18 cm -3 Up to 2E 18 cm -3 .

9. A method for manufacturing a triple-junction solar cell epitaxial structure suitable for aerospace satellites as described in claim 1, characterized in that: A first tunnel junction is grown between the Ge substrate and the InGaAs in-cell. The growth of the InGaAs in-cell includes: a DBR layer, an AlGaAs back surface field layer, an InGaAs base region, an InGaAs emitter region, a GaInP transition layer, and an AlInP window layer grown sequentially on the first tunnel junction. A second tunnel junction is grown between the InGaAs in-cell and the GaInP top cell. The growth of the GaInP top cell includes: an AlGaInP back surface field layer, a GaInP base region, a GaInP emitter region, and an AlInP window layer grown sequentially on the second tunnel junction.

10. A triple-junction solar cell epitaxial structure suitable for aerospace satellites, characterized in that, It is manufactured by the manufacturing method according to any one of claims 1-9.

Images