A method for manufacturing a spatial GaInP / GaInAs / Ge cell epitaxial wafer with base bandgap gradient

Abstract

The present invention discloses a method for manufacturing a space GaInP / GaInAs / Ge cell epitaxial wafer with a base bandgap gradient, which is to change the top cell base of a conventional lattice-matched cell into a structure with a wide bandgap, a gradient bandgap and a consistent lattice constant, that is, the present invention introduces a wide bandgap p-Al2O3 into the top cell base of the space GaInP / InGaAs / Ge lattice-matched cell. x Ga y In 1‑x‑y P / GaInP material. By changing the composition, the band gap of the base layer decreases, while the lattice parameters of each layer are the same. Compared with conventional space GaInP / InGaAs / Ge cells, this structure can increase the collection efficiency of photogenerated carriers while suppressing the dislocation density, and at the same time improve the open circuit voltage of the cell, thereby improving the photoelectric conversion efficiency of the cell.

Description

Technical Field

[0001] The invention relates to the technical field of manufacturing methods of battery epitaxial wafers, and in particular to a manufacturing method of a spatial GaInP / GaInAs / Ge battery epitaxial wafer with base bandgap gradient. Background Art

[0002] GaAs solar cells are the main power source for spacecraft. Compared with other photovoltaic cells, they have good radiation resistance and high photoelectric conversion efficiency. GaAs solar cells for space use have developed into a variety of structures such as conventional lattice-matched GaInP / GaInAs / Ge structure, mismatched GaInP / GaInAs / Ge structure, inverted GaAs structure and more cell structures. The conventional lattice-matched GaInP / GaInAs / Ge structure has a lower photoelectric conversion efficiency than other structures, but because it does not require the growth of a thick buffer layer, its manufacturing cost is lower, and it is currently the most commonly used structure for space batteries.

[0003] The lattice-matched three-section GaInP / GaInAs / Ge structure has a low dislocation density during epitaxial growth due to lattice matching, and the photoelectric conversion efficiency can reach about 30%. However, since the lattice parameters of GaInP and GaInAs are fixed, the band gap widths of the top and middle cells in the structure are not the optimal band gap combination, which limits the open circuit voltage and photoelectric conversion efficiency of the battery with this structure.

[0004] In order to further improve the efficiency of spatial GaInP / GaInAs / Ge lattice-matched cells while controlling the manufacturing cost of cell epitaxial wafers, optimizing the band gap of the top cell or the middle cell is one way. Summary of the invention

[0005] The purpose of the present invention is to provide a method for manufacturing a spatial GaInP / GaInAs / Ge cell epitaxial wafer with a base bandgap gradient, that is, a method for optimizing the top cell bandgap of a spatial GaInP / InGaAs / Ge matching structure and improving the cell open circuit voltage.

[0006] The object of the present invention is achieved by: a method for manufacturing a space GaInP / GaInAs / Ge cell epitaxial wafer with a base bandgap gradient, wherein: a quaternary material Al is deposited in the top cell base region; x Ga y In 1-x-y P, by changing the composition of Al, Ga and In to make the bandgap width change gradually; the designed Al x Ga y In 1-x-yThe P bandgap width is larger than that of the top cell GaInP, which increases the open circuit voltage of the cell. At the same time, the decreasing design of the bandgap width makes the top cell base region form a conduction band step, which is conducive to the collection of photogenerated carriers and minority carriers. In addition, through the Al x Ga y In 1-x-y The control of the P component makes it match the GaInP lattice, reducing the recombination caused by dislocations, thereby improving the photoelectric conversion efficiency of the entire battery.

[0007] The specific steps are as follows:

[0008] Using MOCVD equipment technology, n-AlGaInP nucleation layer, n-GaAs / n-GaInAs buffer layer, n++-GaAs / p++-GaAs tunneling junction layer, p-AlGaAs / p-AlGaInAs (DBR) reflective layer, p-GaInP back field layer, p-GaInAs base layer are deposited on the p-Ge substrate in sequence, and then n-GaInAs emitter layer, n-AlInP window layer, n++-GaInP / p++-AlGaAs tunneling junction layer, p-AlGaInP back field layer, p-Al x Ga y In 1-x-y A P / GaInP base layer is deposited, followed by an n-GaInP emitter layer, an n-AlInP window layer and an n+-GaAs ohmic contact layer.

[0009] The substrate material is p-Ge, with a thickness of 130-150 μm, doped with Ga source, and the doping concentration is 0.2E18-3E18 cm -3 ,9° cutting angle;

[0010] The deposition thickness of the n-AlGaInP nucleation layer is 0.01 μm, and the doping concentration is 1 to 2×10 18 cm -3 .

[0011] The n-GaAs / n-GaInAs buffer layer is deposited with a thickness of 0.5 μm and a doping concentration of ≥1×10 18 cm -3 .

[0012] n++-GaAs / p++-GaAs tunneling junction layer, wherein the n++-GaAs layer is deposited with a thickness of 0.01 to 0.03 μm and a doping concentration of ≥5×10 18 cm -3 The p++-GaAs layer has a deposition thickness of 0.01 to 0.03 μm and a doping concentration of ≥1×10 19 cm -3 .

[0013] The p-AlGaAs / p-AlGaInAs (DBR) reflective layer deposition thickness is 1.8 μm and the doping concentration is 5×10 17 cm -3 .

[0014] The p-GaInP back field layer is deposited with a thickness of 0.07 μm and a doping concentration of 5×10 17 ~1×10 18 cm -3 .

[0015] The p-GaInAs base layer has a total thickness of 2.1 μm and a doping concentration of 2 to 8×10 16 cm -3 .

[0016] The deposition thickness of the n-GaInAs emitter layer is 0.1 μm and the doping concentration is 1×10 18 cm -3 .

[0017] The n-AlInP window layer is deposited with a thickness of 0.1 μm and a doping concentration of 1×10 18 cm -3 .

[0018] n++-GaInP / p++-AlGaAs tunneling junction layer, where the n++-GaInP layer is deposited with a thickness of 0.01 to 0.03 μm and a doping concentration of ≥5×10 18 cm -3 The p++-AlGaAs layer has a deposition thickness of 0.01 to 0.03 μm and a doping concentration of ≥5×10 19 cm -3 .

[0019] The p-AlGaInP back field layer is deposited with a thickness of 0.1 μm and a doping concentration of 1 to 2×10 18 cm -3 .

[0020] p-Al x Ga y In 1-x-y The total deposition thickness of the P / GaInP base layer is 0.7μm, which is divided into seven layers of materials: Al 51.4 Ga 6.2 In 42.4 P, Al 51.6 Ga 13.0 In 35.3 P.Al 51.8 Ga 19.9 In 28.3 P.Al 52.0 Ga 26.7 In21.3 P.Al 52.2 Ga 33.5 In 14.3 P.Al 52.4 Ga 40.3 In 7.3 P.Ga 49.7 In 50.3 P, the deposition thickness is 0.1 μm, and the doping concentration is 1 to 8×10 16 cm -3 .

[0021] The deposition thickness of the n-GaInP emitter layer is 0.1 μm and the doping concentration is 1×10 18 cm -3 .

[0022] The n-AlInP window layer is deposited with a thickness of 0.1 μm and a doping concentration of 1×10 18 cm -3 .

[0023] The deposition thickness of the n+-GaAs ohmic contact layer is 0.5 μm, and the doping concentration is greater than 5×10 18 cm -3 .

[0024] The present invention provides a method for manufacturing a space GaInP / GaInAs / Ge cell epitaxial wafer with a base bandgap gradient, which has the advantages that compared with the conventional space GaInP / InGaAs / Ge cell structure, the present invention introduces a base bandgap gradient Al in the top cell. x Ga y In 1-x-y The P / GaInP structure reduces the bandgap width of the top cell by changing the Al, Ga, and In components, while matching the lattices of the various materials. This design increases the overall bandgap width of the top cell, which improves the open circuit voltage of the cell. In addition, the design of the bandgap width gradient is conducive to the collection of photogenerated minority carriers, which is beneficial to the short-circuit current of the cell. Finally, the consistency of the lattice constant controls the defect density during material growth. In general, this method can improve the photoelectric conversion efficiency of spatial GaInP / InGaAs / Ge matching cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of an epitaxial layer structure involved in the present invention;

[0026] Figure 2 The present invention relates to the top battery Al x Ga y In 1-x-y P / GaInP base layer band structure, Al x Gay In 1-x- y The P / GaInP base layer consists of seven layers of materials with decreasing band gaps;

[0027] The accompanying drawings are marked as follows:

[0028] 100: P-type Ge substrate; 101: n-AlGaInP nucleation layer;

[0029] 102: n-GaAs / n-GaInAs buffer layer; 103: n++-GaAs / p++-GaAs tunneling junction layer;

[0030] 104: p-AlGaAs / p-AlGaInAs (DBR) reflective layer;

[0031] 105: p-GaInP back field layer; 106: p-GaInAs base layer;

[0032] 107: n-GaInAs emitter layer; 108: n-AlInP window layer;

[0033] 109: n++-GaInP / p++-AlGaAs tunneling junction layer;

[0034] 110: p-AlGaInP back field layer; 111: p-Al x Ga y In 1-x-y P / GaInP base layer;

[0035] 112: n-GaInP emitter layer; 113: n-AlInP window layer;

[0036] 114: n+-GaAs ohmic contact layer. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] A method for manufacturing a base bandgap gradient space GaInP / GaInAs / Ge cell epitaxial wafer, the device used is 2600G3 MOCVD (Metal Organic Chemical Vapor Deposition) produced by AXITRON of Germany, the substrate is a p-Ge substrate, the Ga source is doped, and the doping concentration is 0.2E18-3E18cm -3 , thickness is 130-150μm, cutting angle is 9°, MO sources used are TMGa, TMAl and TMIn, doping sources used are CCl4, DEZn and SiH4, and special gases used are AsH3 and PH3.

[0039] The specific steps are as follows:

[0040] A. MOCVD reaction chamber is heated to 400℃ and PH3 is introduced. The reaction chamber is heated to 690℃ and the pressure is set to 230mbar. N-type doping of about 1×10 18 cm -3 The temperature of the reaction chamber was lowered to 620°C, and TMAl, TMGa, TMIn sources and special gas PH3 were introduced to deposit the n-AlGaInP nucleation layer. The AlGaInP nucleation layer was deposited to a thickness of 0.01 μm, and the doping source was SiH4 with a doping concentration of 1 to 2×10 18 cm -3 ;

[0041] B. The temperature of the reaction chamber is raised to 650°C and the pressure is set to 450 mbar. The n-GaAs / n-GaInAs buffer layer is deposited on the n-AlGaInP nucleation layer. The thickness of the n-GaAs / n-GaInAs buffer layer is 0.5 μm. The SiH4 source is doped with a doping concentration of ≥1×10 18 cm -3 ;

[0042] C. The temperature of the reaction chamber is set to 630°C and the pressure is set to 50 mbar. The n++-GaAs layer is deposited on the GaAs / GaInAs buffer layer. The n++-GaAs layer is deposited to a thickness of 0.01-0.03 μm and doped with SiH4 source with a doping concentration of ≥5×10 18 cm -3 The reaction temperature is lowered to 620°C, and a p++-GaAs layer is deposited on the n++-GaAs layer. The p++-GaAs layer is deposited to a thickness of 0.01-0.03 μm and doped with a CCl4 source with a doping concentration of ≥1×10 19 cm -3 ;

[0043] D. The temperature of the reaction chamber is raised to 650°C, and a p-AlGaAs / p-AlGaInAs (DBR) reflective layer is deposited on the p++-GaAs layer. The thickness of the p-AlGaAs / p-AlGaInAs reflective layer is 1.8 μm, and the DEZn source is doped at a doping concentration of 5×10 17 cm -3 ;

[0044] E. A p-GaInP back field layer was deposited on the AlGaAs / AlGaInAs reflective layer at 650°C. The p-GaInP back field layer had a thickness of 0.07 μm and was doped with a DEZn source at a doping concentration of 5×10 17 ~1×10 18 cm -3 ;

[0045] F. Deposit a p-GaInAs base layer on the GaInP back field layer at 650°C with a thickness of 2.1 μm and dope it with DEZn source at a doping concentration of 5×10 17 ~1×10 18 cm -3 ;

[0046] G. Deposit an n-GaInAs emitter layer on the p-GaInAs base layer at 650°C. The thickness of the n-GaInAs emitter layer is 0.1 μm. The SiH4 source is doped at a doping concentration of 1×10 18 cm -3 ;

[0047] H. Deposit an n-AlInP window layer on the GaInAs emitter layer at 650°C. The n-AlInP window layer is deposited to a thickness of 0.1 μm and doped with SiH4 source at a doping concentration of 1×10 18 cm -3 ;

[0048] I. The temperature of the reaction chamber is reduced to 620°C, and an n++-GaInP / p++-AlGaAs tunneling junction layer is deposited on the AlInP window layer, wherein the n++-GaInP layer is deposited to a thickness of 0.01-0.03 μm and doped with a SiH4 source with a doping concentration of ≥5×10 18 cm -3 The p++-AlGaAs layer is deposited with a thickness of 0.01-0.03 μm, and the doping source is CCl4, with a doping concentration of ≥5×10 19 cm -3 ;

[0049] J. Deposit a p-AlGaInP back field layer on the GaInP / AlGaAs tunneling junction layer at 620°C. The p-AlGaInP back field layer is deposited to a thickness of 0.1 μm and doped with a DEZn source at a doping concentration of 1 to 2×10 18 cm -3 ;

[0050] K, the chamber temperature rises to 630°C, and p-Al is deposited on the AlGaInP back field layer. x Ga y In 1-x-y The P / GaInP base layer has a total deposition thickness of 0.7 μm and is divided into seven layers of materials, with the deposition components being Al 51.4 Ga 6.2 In 42.4 P, Al 51.6 Ga 13.0 In 35.3 P.Al 51.8 Ga 19.9 In 28.3 P.Al 52.0 Ga 26.7 In 21.3 P.Al 52.2 Ga 33.5 In 14.3 P.Al 52.4 Ga 40.3 In 7.3 P.Ga 49.7 In 50.3 The P materials have a deposition thickness of 0.1 μm and are doped with DEZn source at a doping concentration of 1 to 8×10 16 cm -3 ;

[0051] L. Deposit an n-GaInP emitter layer on the GaInP base layer at 630°C. The thickness of the n-GaInP emitter layer is 0.1 μm. The SiH4 source is doped at a doping concentration of 1×10 18 cm -3 ;

[0052] M. Deposit an n-AlInP window layer on the GaInP emitter layer at 630°C. The thickness of the n-AlInP window layer is 0.1 μm. The SiH4 source is doped at a doping concentration of 1×10 18 cm -3 ;

[0053] N. Deposit an n+-GaAs ohmic contact layer on the AlInP window layer at 630°C. The n+-GaAs ohmic contact layer is deposited to a thickness of 0.5 μm and doped with a SiH4 source with a doping concentration greater than 5×10 18 cm-3 .

[0054] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a spatial GaInP / GaInAs / Ge cell epitaxial wafer with a base bandgap gradient, characterized in that: The top cell base region is deposited with a bandgap gradient and lattice-matched Al x GayIn 1-x-y P / GaInP layer, the specific steps are as follows: Using metal organic chemical vapor deposition equipment technology, n-AlGaInP nucleation layer, n-GaAs / n-GaInAs buffer layer, n++-GaAs / p++-GaAs tunneling junction layer, p-AlGaAs / p-AlGaInAs (DBR) reflective layer, p-GaInP back field layer, p-GaInAs base layer, n-GaInAs emitter layer, n-AlInP window layer, n++-GaInP / p++-AlGaAs tunneling junction layer, p-AlGaInP back field layer, p-Al x GayIn 1-x-y P / GaInP base layer, n-GaInP emitter layer, n-AlInP window layer and n+-GaAs ohmic contact layer; p-Al x GayIn 1-x-y The total deposition thickness of the P / GaInP base layer is 0.7μm, which is divided into seven layers of materials: Al 51.4 Ga 6.2 In 42.4 P, Al 51.6 Ga 13.0 In 35.3 P.Al 51.8 Ga 19.9 In 28.3 P.Al 52.0 Ga 26.7 In 21.3 P.Al 52.2 Ga 33.5 In1 4.3 P.Al 52.4 Ga 40.3 In 7.3 P.Ga 49.7 In 50.3 P, the deposition thickness is 0.1 μm, doped with DEZn source, and the doping concentration is 1~8×10 16 cm -3 .

2. The method for manufacturing a spatial GaInP / GaInAs / Ge cell epitaxial wafer with base bandgap gradient according to claim 1, characterized in that: The substrate material is p-Ge, doped with Ga source, and the doping concentration is 0.2E18~3E18cm -3 , thickness is 130-150μm, cutting angle is 9°; The n-AlGaInP nucleation layer is deposited with a thickness of 0.01 μm and doped with SiH4 source at a doping concentration of 1 to 2×10 18 cm -3 ; The n-GaAs / n-GaInAs buffer layer is deposited with a thickness of 0.5 μm and doped with SiH4 source with a doping concentration of ≥1×10 18 cm -3 ; n++-GaAs / p++-GaAs tunneling junction layer, where the n++-GaAs layer is deposited with a thickness of 0.01-0.03 μm, doped with SiH4 source, and the doping concentration is ≥5×10 18 cm -3 The p++-GaAs layer is deposited with a thickness of 0.01-0.03 μm and doped with a CCl4 source with a doping concentration of ≥1×10 19 cm -3 ; The p-AlGaAs / p-AlGaInAs (DBR) reflective layer is deposited with a thickness of 1.8 μm and doped with DEZn source at a doping concentration of 5×10 17 cm -3 ; The p-GaInP back field layer is deposited with a thickness of 0.07 μm and doped with DEZn source at a doping concentration of 5×10 17 ~1×10 18 cm -3 ; The p-GaInAs base layer is deposited to a thickness of 2.1 μm and doped with DEZn source with a doping concentration of 2 to 8×10 16 cm -3 ; The deposition thickness of the n-GaInAs emitter layer is 0.1 μm, and the doping concentration is 1×10 18 cm -3 ; The n-AlInP window layer is deposited with a thickness of 0.1 μm and doped with SiH4 source at a doping concentration of 1×10 18 cm -3 ; n++-GaInP / p++-AlGaAs tunneling junction layer, wherein the thickness of the n++-GaInP layer is 0.01-0.03 μm, doped with SiH4 source, and the doping concentration is ≥5×10 18 cm -3 The thickness of the p++-AlGaAs layer is 0.01-0.03 μm, and the doping concentration is ≥5×10 19 cm -3 ; The p-AlGaInP back field layer is deposited with a thickness of 0.1 μm and doped with DEZn source at a doping concentration of 1 to 2×10 18 cm -3 ; The deposition thickness of the n-GaInP emitter layer is 0.1 μm, and the doping concentration is 1×10 18 cm -3 ; The thickness of the n-AlInP window layer is 0.1 μm, and it is doped with SiH4 source and the doping concentration is 1×10 18 cm -3 ; The thickness of the n+-GaAs ohmic contact layer is 0.5 μm, and the doping concentration is greater than 5×10 18 cm -3 .

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