A Germanium-based Gallium Arsenide Solar Cell and Preparation Method

Abstract

The present invention discloses a germanium-based gallium arsenide solar cell and a preparation method thereof, belonging to the technical field of solar cells, and comprising, from bottom to top, a germanium substrate, a GaInP nucleation layer, a GaInAs buffer layer, a first tunneling junction, a Ga 1‑a In a As lattice graded buffer layer, (AlGa) 1‑ b In b As / Ga 1‑b In b As first period structure overshoot layer, Ga 1‑ c In c As subcell, second tunnel junction, (AlGa) 1‑d In d As / Ga 1‑ d In d As periodic structure lattice graded layer, (AlGa) 1‑e In e As / Ga 1‑e In e As second periodic structure overshoot layer, Ga 1‑f In f As 1‑g P g Subcell, third tunnel junction, (AlGa) 1‑h In h P subcell and Ga 1‑j In j As cap layer. It can improve the photoelectric conversion efficiency and radiation resistance of germanium-based gallium arsenide solar cells.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a germanium-based gallium arsenide solar cell and a preparation method thereof. Background Art

[0002] Compared with traditional single-crystal silicon solar cells for space use, gallium arsenide solar cells based on germanium substrates have the advantages of high conversion efficiency, high temperature resistance, radiation resistance, and strong reliability. They have been widely used in primary power supplies for spacecraft, greatly improving the payload capacity and on-orbit life of spacecraft. At present, the most mature space solar cell products are germanium-based triple-junction solar cells, with a band gap distribution of 1.9 / 1.4 / 0.67eV. Among them, due to the large band gap difference between the 1.4eV middle cell and the 0.67eV germanium sub-cell, the output current of each sub-cell does not match, limiting the further improvement of the cell conversion efficiency. In order to obtain higher conversion efficiency, the design of solar cells needs to further consider spectral matching. Summary of the invention

[0003] The present invention provides a germanium-based gallium arsenide solar cell and a preparation method thereof, which are used to improve the photoelectric conversion efficiency of the germanium-based gallium arsenide solar cell and enhance the radiation resistance of the germanium-based gallium arsenide solar cell.

[0004] The first object of the present invention is to provide a germanium-based gallium arsenide solar cell, which comprises, from bottom to top, a germanium substrate, a GaInP nucleation layer, a GaInAs buffer layer, a first tunneling junction, and a Ga 1-a In a As lattice graded buffer layer, (AlGa) 1-b In b As / Ga 1- b In b As first period structure overshoot layer, Ga 1-c In c As subcell, second tunnel junction, (AlGa) 1-d In d As / Ga 1-d In d As periodic structure lattice graded layer, (AlGa) 1-e In e As / Ga 1-e In e As second periodic structure overshoot layer, Ga 1-f In f As 1-g P g Subcell, third tunnel junction, (AlGa) 1-h In h P subcell and Ga 1-j Inj As cap layer; a lower electrode is provided on the germanium substrate, 1-j In j The As cap layer is provided with an upper electrode; wherein: the Ga 1-a In a The In component a of the As lattice graded buffer layer changes gradually from 0 to c, 0≤c≤0.5, 0.4≤x≤1, 0≤f≤0.8, 0≤g≤1, 0.4≤y≤1, 0.4≤h≤1, c≥d≥0, b≥c, e≤d, 0≤j≤0.5.

[0005] Preferably, the Ga 1-c In c The As subcell includes p-type doped Ga 1-c In c As base layer, an unintentionally doped i layer and an n-type doped emitter layer, wherein:

[0006] Ga 1-c In c As base layer: doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm;

[0007] The unintentionally doped i-layer is Ga 1-c In c As or Ga 1-x In x P material, thickness is 10nm~1000nm;

[0008] The emitter layer is Ga 1-c In c As or Ga 1-x In x P material, doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm.

[0009] Preferably, the Ga 1-a In a The lattice constant of the As lattice graded buffer layer changes from matching the Ge substrate to matching the Ga 1-c In c As sub-battery matching.

[0010] Preferably, the (AlGa) 1-b In b As / Ga 1-b Inb The In content of the overshoot layer of the first periodic structure of As is greater than that of Ga 1- c In c The In component of the As subcell, the (AlGa) 1-b In b As / Ga 1-b In b The number of periods of the As first periodic structure overshoot layer ranges from 2 to 20, and in each period (AlGa) 1-b In b The thickness of As is 5nm to 300nm, Ga 1-b In b The thickness of As is 5 nm to 300 nm.

[0011] Preferably, the Ga 1-f In f As 1-g P g The subcell includes a p-type doped base layer, an unintentionally doped i-layer and an n-type doped emitter layer, wherein:

[0012] Ga 1-f In f As 1-g P g Base layer: doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm;

[0013] The unintentionally doped i-layer is Ga 1-f In f As 1-g P g or Ga 1-y In y P material, thickness is 10nm~1000nm;

[0014] The emitter layer is Ga 1-f In f As 1-g P g or Ga 1-y In y P material, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness 30nm~5000nm.

[0015] Preferably, the (AlGa) 1-d In dAs / Ga 1-d In d The In component of the As periodic structure lattice graded layer changes gradually, and the (AlGa) 1-d In d As / Ga 1-d In d The lattice constant of the As periodic structure lattice graded layer changes from 1-c In c The As subcell is graded to match the Ga 1-f In f As 1-g P g Subcells are matched, and each gradient is made of (AlGa) 1- d In d As / Ga 1-d In d As is composed of a periodic structure, and the number of periods ranges from 2 to 20.

[0016] Preferably, the (AlGa) 1-e In e As / Ga 1-e In e The lattice constant of the overshoot layer of the second periodic structure of As is not greater than that of Ga 1-f In f As 1-g P g Lattice constant of subcell; (AlGa) 1-e In e As / Ga 1-e In e The number of periods of the overshoot layer of the second periodic structure of As ranges from 2 to 20, and in each period (AlGa) 1-e In e The thickness of As is 5nm to 300nm, Ga 1-e In e The thickness of As is 5 nm to 300 nm.

[0017] Preferably, the (AlGa) 1-h In h The P subcell includes a p-type doped base layer, an unintentionally doped i-layer and an n-type doped emitter layer; wherein:

[0018] The base layer doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm;

[0019] The thickness of the unintentionally doped i layer is 10nm to 1000nm; the doping concentration of the emitter layer is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm.

[0020] Preferably, the Ga 1-j In j As cap layer is n-type doped Ga 1-j In j As, where 0≤j≤0.5, and the doping concentration is 1×10 18 ~1×10 21 cm -3 , the thickness range is 50nm~500nm.

[0021] The second object of the present invention is to provide a method for preparing a germanium-based gallium arsenide solar cell, comprising:

[0022] S1. Using MOCVD technology to grow a GaInP nucleation layer on a P-type germanium substrate; wherein: the n-type dopant is Si or Se, the growth temperature is 450°C to 700°C, the thickness ranges from 20 to 500nm, and an n-type Ge layer is formed by diffusion of phosphorus atoms in the nucleation layer, and a germanium subcell is formed with the p-type germanium substrate;

[0023] S2. Using MOCVD technology to grow a GaInAs buffer layer on the GaInP nucleation layer; wherein: the n-type dopant is Si or Se, the growth temperature is 500° C. to 750° C., and the thickness ranges from 100 to 2000 nm;

[0024] S3, using MOCVD technology to grow a first tunnel junction on the GaInAs buffer layer; the first tunnel junction includes an n-type doped GaAs layer and a p-type doped AlGaAs layer, wherein: the dopant of the GaAs layer is Se or Te, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, growth temperature is 450℃~700℃;

[0025] S4. Use MOCVD technology to grow Ga on the first tunnel junction 1-a In a As lattice gradient buffer layer; Ga 1-a Ina The In component a of the As lattice gradient buffer layer gradually changes from 0 to c, and the p-type doping concentration is 1×10 17 cm -3 ~1×10 19 cm -3 The growth temperature is 600℃~750℃, and the lattice constant is gradually changed from matching the germanium substrate to matching the Ga 1-c In c As sub-battery matching;

[0026] S5. Using MOCVD technology in Ga 1-a In a As lattice graded buffer layer (AlGa) 1-b In b As / Ga 1-b In b As first periodic structure overshoot layer; the (AlGa) 1-b In b As / Ga 1-b In b The doping concentration of the As overshoot layer in the first periodic structure is 1×10 17 ~1×10 19 cm -3 , the growth temperature is 600℃~750℃, and the In component is greater than the Ga 1-c In c As subcell In component, the number of cycles of the structure ranges from 2 to 20, in each cycle (AlGa) 1-b In b The thickness of As is 5nm to 300nm, Ga 1- b In b The thickness of As is 5nm to 300nm;

[0027] S6. Using MOCVD technology in (AlGa) 1-b In b As / Ga 1-b In b As first periodic structure Ga is grown on the overshoot layer 1- c In c As subcell; Ga 1-c In c The As subcell includes p-type doped Ga 1-c In c As base layer, unintentionally doped i layer and n-type doped emitter layer, among which: 1-c In c In the As base layer: 0≤c≤0.5, doping concentration 1×1016 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; the unintentionally doped i layer is Ga 1-c In c As or Ga 1-x In x P material, 0.4≤x≤1, thickness is 10nm~1000nm; the emission layer is Ga 1-c In c As or Ga 1-x In x P material, 0.4≤x≤1, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm;

[0028] S7, using MOCVD technology in Ga 1-c In c The second tunnel junction is grown on the As subcell; the second tunnel junction includes an n-type doped AlGaInP layer and a p-type doped AlGaInAs layer, wherein the dopant of the AlGaInP layer is Se or Te, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaInAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, growth temperature is 450℃~700℃;

[0029] S8, using MOCVD technology to grow (AlGa) on the second tunnel junction 1-d In d As / Ga 1-d In d As periodic structure lattice gradient layer; (AlGa) 1-d In d As / Ga 1-d In d The In component of the As periodic structure lattice gradient layer changes gradually, and the range of change is c≥d≥0. Each gradient change is composed of (AlGa) 1-d In d As / Ga 1-d In d As is composed of periodic structures, and the number of periods ranges from 2 to 20;

[0030] S9, using MOCVD technology in (AlGa) 1-d In d As / Ga 1-d In d As periodic structure lattice graded layer growth (AlGa) 1-e In e As / Ga 1-e In e As second periodic structure overshoot layer; the growth temperature is 600℃~750℃, and its lattice constant is not greater than Ga 1-f In f As 1-g P g The lattice constant of the subcell, the number of periods of the structure ranges from 2 to 20, and in each period (AlGa) 1-e In e The thickness of As is 5nm to 300nm, Ga 1-e In e The thickness of As is 5nm to 300nm;

[0031] S9, using MOCVD technology in (AlGa) 1-e In e As / Ga 1-e In e As second periodic structure Ga grown on overshoot layer 1- f In f As 1-g P g Subcell; Ga 1-f In f As 1-g P g The subcell includes a p-type doped base layer, an unintentionally doped i-layer, and an n-type doped emitter layer. 1-f In f As 1-g P g In the base layer: 0≤f≤0.8, 0≤g≤1, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; the unintentionally doped i layer is Ga 1-f In f As 1-g P g or Ga 1-y In y P material, 0.4≤y≤1, thickness is 10nm~1000nm; the emission layer is Ga 1-fIn f As 1-g P g or Ga 1-y In y P material, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm;

[0032] S10, using MOCVD technology in Ga 1-f In f As 1-g P g The third tunnel junction is grown on the subcell; the third tunnel junction includes an n-type doped AlGaInP layer and a p-type doped AlGaInAs layer, and the dopant of the AlGaInP layer is Se or Te with a doping concentration of 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaInAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, growth temperature is 450℃~700℃;

[0033] S11. Use MOCVD technology to grow (AlGa) on the third tunnel junction 1-h In h P subcell; (AlGa) 1-h In h The P subcell includes a p-type doped base layer, an unintentionally doped i layer, and an n-type doped emitter layer, 0.4≤h≤1, and the doping concentration of the base layer is 1×10 16 cm -3 ~1×10 19 cm -3 , with a thickness of 30nm to 5000nm; the thickness of the unintentionally doped i layer is 10nm to 1000nm; the doping concentration of the emitter layer is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm;

[0034] S12, using MOCVD technology in (AlGa) 1-h In h The n-type doped Ga is grown on the P subcell 1-j In jAs cap layer; 0≤j≤0.5, doping concentration is 1×10 18 ~1×10 21 cm -3 , thickness range is 50nm~500nm;

[0035] S13, preparing the upper metal electrode, the lower metal electrode and the anti-reflection film of the battery.

[0036] The advantages and positive effects of the present invention are:

[0037] The present invention uses a lattice gradient buffer layer to achieve a gradual enlargement of the lattice constant, and then prepares an overshoot layer with a periodic structure, which plays the role of stress regulation and distributed Bragg reflector. On this basis, a GaInAs sub-cell is prepared, and then on the basis of the lattice constant of the GaInAs sub-cell, a periodic structure gradient buffer layer with a gradually reduced lattice constant and a second periodic structure overshoot layer are used to reduce the lattice constant, regulate stress and reflect the GaInAs sub-cell. 1-f In f As 1-g P g The photons of the subcells make the subsequent growth of Ga 1-f In f As 1-g P g Subcell and (AlGa) 1-h In h The P subcell uses lower In and Al components to achieve the growth of high-quality epitaxial materials and improve the conversion efficiency of solar cells;

[0038] The present invention inserts a sub-cell with a band gap of 1.0eV to 1.2eV between a 1.4eV medium cell and a 0.67eV germanium sub-cell to form a 1.9 / 1.4 / 1.0 / 0.67eV four-junction solar cell, which can more efficiently utilize the medium and long wavelength photons originally absorbed by the Ge sub-cell, improve the utilization rate of the solar cell for the AM0 spectrum, and further improve the photoelectric conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 4 is a structural diagram of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0041] like Figure 1 As shown, the technical solution of the present invention is:

[0042] A germanium-based gallium arsenide solar cell comprises, from bottom to top, a germanium substrate, a GaInP nucleation layer, a GaInAs buffer layer, a first tunneling junction, and a Ga 1-a In a As lattice graded buffer layer, (AlGa) 1-b In b As / Ga 1-b In b As first period structure overshoot layer, Ga 1-c In c As subcell, second tunnel junction, (AlGa) 1-d In d As / Ga 1-d In d As periodic structure lattice graded layer, (AlGa) 1-e In e As / Ga 1-e In e As second periodic structure overshoot layer, Ga 1-f In f As 1-g P g Subcell, third tunnel junction, (AlGa) 1-h In h P sub-cell, Ga 1-j In j As cap layer. The germanium substrate is provided with a lower electrode. 1-j In j The As cap layer is provided with an upper electrode.

[0043] The Ga 1-c In c The As subcell includes p-type doped Ga 1-c In c As base layer, unintentionally doped i layer and n-type doped emitter layer, of which Ga 1-c In c As base layer: 0≤c≤0.5, doping concentration 1×10 16 cm -3 -1×10 19 cm -3 , thickness 30nm-5000nm; the unintentionally doped i layer can be Ga 1-c In c As or Ga 1-x In x P material, 0.4≤x≤1, thickness 10nm-1000nm; the emission layer can be Ga 1-c In c As or Ga 1-x In xP material, 0.4≤x≤1, doping concentration 1×10 16 cm -3 -1×10 19 cm -3 , thickness 30nm-5000nm.

[0044] The Ga 1-a In a The In component of the As lattice gradient buffer layer changes gradually from 0 to c, that is, its lattice constant changes from matching the germanium substrate to matching the Ga 1-c In c As sub-battery matching.

[0045] The (AlGa) 1-b In b As / Ga 1-b In b The In content of the overshoot layer of the first periodic structure of As is greater than that of Ga 1-c In c The In component of the As subcell, i.e. b ≥ c, plays a role in stress regulation. At the same time, the number of cycles of the structure ranges from 2 to 20, which plays a role in reflecting and transmitting Ga 1-c In c The role of photons in the As subcell, in each cycle (AlGa) 1-b In b The thickness of As is 5nm-300nm, Ga 1- b In b The thickness of As is 5nm-300nm.

[0046] The Ga 1-f In f As 1-g P g The subcell includes a p-type doped base layer, an unintentionally doped i-layer and an n-type doped emitter layer, wherein Ga 1-f In f As 1-g P g Base layer: 0≤f≤0.8, 0≤g≤1, doping concentration 1×10 16 cm -3 -1×10 19 cm -3 , thickness 30nm-5000nm; the unintentionally doped i layer can be Ga 1-f In f As 1-g P g or Ga 1-y In yP material, 0.4≤y≤1, thickness 10nm-1000nm; the emission layer can be Ga 1-f In f As 1-g P g or Ga 1-y In y P material, doping concentration 1×10 16 cm -3 -1×10 19 cm -3 , thickness 30nm-5000nm.

[0047] The (AlGa) 1-d In d As / Ga 1-d In d The In component of the As periodic structure lattice gradient layer changes gradually, and the range of change is c≥d≥0, that is, its lattice constant changes from the Ga 1-c In c The As subcell is graded to match the Ga 1- f In f As 1-g P g Sub-battery. At the same time, each gradient is composed of (AlGa) 1-d In d As / Ga 1-d In d As periodic structure, the number of periods ranges from 2 to 20, which plays a role in reflecting and transmitting Ga 1-f In f As 1-g P g The role of photons in sub-cells.

[0048] The (AlGa) 1-e In e As / Ga 1-e In e The lattice constant of the overshoot layer of the second periodic structure of As is not greater than that of Ga 1- f In f As 1-g P g The lattice constant of the subcell plays a role in stress regulation. At the same time, the number of periods of the structure ranges from 2 to 20, which plays a role in reflecting and transmitting Ga 1-f In f As 1-g P g The role of photons in the subcell, in each cycle (AlGa) 1-e In eThe thickness of As is 5nm-300nm, Ga 1-e In e The thickness of As is 5nm-300nm.

[0049] The (AlGa) 1-h In h The P subcell includes a p-type doped base layer, an unintentionally doped i layer, and an n-type doped emitter layer, where 0.4≤h≤1, and the base layer doping concentration is 1×10 16 cm -3 -1×10 19 cm -3 , thickness 30nm-5000nm; thickness of the unintentionally doped i layer 10nm-1000nm; doping concentration of the emitter layer 1×10 16 cm -3 -1×10 19 cm -3 , thickness 30nm-5000nm.

[0050] The Ga 1-j In j As cap layer is n-type doped Ga 1-j In j As, where 0≤j≤0.5, and the doping concentration is 1×10 18 -1×10 21 cm -3 , thickness range is 50nm-500nm.

[0051] The preparation process of the above battery is:

[0052] The GaInP nucleation layer, GaInAs buffer layer, first tunneling junction, GaInAs layer and GaInAs layer are grown on a P-type germanium substrate in sequence using MOCVD technology. 1-a In a As lattice graded buffer layer, (AlGa) 1-b In b As / Ga 1-b In b As first period structure overshoot layer, Ga 1-c In c As subcell, second tunnel junction, (AlGa) 1-d In d As / Ga 1-d In d As periodic structure lattice graded layer, (AlGa) 1-e In e As / Ga 1- e In e As second periodic structure overshoot layer, Ga 1-fIn f As 1-g P g Subcell, third tunnel junction, (AlGa) 1-h In h P sub-cell, Ga 1- j In j As cap layer. Among them:

[0053] The n-type dopant of the GaInP nucleation layer is Si or Se, the growth temperature is 450℃~700℃, the thickness range is 20~500nm, and the n-type Ge layer is formed by the diffusion of phosphorus atoms in the nucleation layer, which constitutes a germanium subcell with the p-type germanium substrate;

[0054] The n-type dopant of the GaInAs buffer layer is Si or Se, the growth temperature is 500°C to 750°C, and the thickness ranges from 100 to 2000nm;

[0055] The first tunnel junction includes an n-type doped GaAs layer and a p-type doped AlGaAs layer, wherein the dopant of the GaAs layer is Se or Te with a doping concentration of 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, and the growth temperature is 450℃~700℃; the dopant of AlGaAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, growth temperature is 450℃~700℃;

[0056] Ga 1-a In a The In component of the As lattice gradient buffer layer changes gradually from 0 to c, p-type doping, and the doping concentration is 1×10 17 cm -3 ~1×10 19 cm -3 The growth temperature is 600℃~750℃, and the lattice constant is gradually changed from matching the germanium substrate to matching the Ga 1-c In c As sub-battery matching.

[0057] (AlGa) 1-b In b As / Ga 1-b In b As first periodic structure overshoot layer, doping concentration is 1×10 17 ~1×10 19 cm -3, the growth temperature is 600℃~750℃, and its In component is greater than Ga 1-c In c The In component of the As subcell, i.e. b ≥ c, plays a role in stress regulation. At the same time, the number of cycles of the structure ranges from 2 to 20, and in each cycle (AlGa) 1-b In b The thickness of As is 5nm to 300nm, Ga 1-b In b As has a thickness of 5nm to 300nm and can reflect and transmit Ga 1-c In c The photons of the As sub-cell are reabsorbed by the junction sub-cell, thereby improving the quantum efficiency and radiation resistance of the sub-cell.

[0058] Ga 1-c In c The As subcell includes p-type doped Ga 1-c In c As base layer, unintentionally doped i layer and n-type doped emitter layer, of which Ga 1-c In c As base layer: 0≤c≤0.5, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness 30nm~5000nm; the unintentionally doped i layer can be Ga 1-c In c As or Ga 1-x In x P material, 0.4≤x≤1, thickness 10nm~1000nm; the emission layer can be Ga 1-c In c As or Ga 1-x In x P material, 0.4≤x≤1, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness 30nm~5000nm.

[0059] The second tunnel junction includes an n-type doped AlGaInP layer and a p-type doped AlGaInAs layer, wherein the dopant of the AlGaInP layer is Se or Te, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaInAs layer is Zn or C, and the doping concentration is 1×10 19~1×10 21 cm -3 , thickness range is 5nm~50nm, and growth temperature is 450℃~700℃.

[0060] (AlGa) 1-d In d As / Ga 1-d In d The In component of the As periodic structure lattice gradient layer changes gradually, and the range of change is c≥d≥0, that is, its lattice constant changes from the Ga 1-c In c The As subcell is graded to match the Ga 1-f In f As 1-g P g Sub-battery. At the same time, each gradient is composed of (AlGa) 1-d In d As / Ga 1-d In d As periodic structure, the number of periods ranges from 2 to 20, which plays a role in reflecting and transmitting Ga 1-f In f As 1-g P g The role of photons in sub-cells.

[0061] (AlGa) 1-e In e As / Ga 1-e In e As second periodic structure overshoot layer, the growth temperature is 600–750°C, and its lattice constant is no greater than that of Ga 1-f In f As 1-g P g The lattice constant of the subcell plays a role in stress regulation. At the same time, the number of periods of the structure ranges from 2 to 20, which plays a role in reflecting and transmitting Ga 1-f In f As 1-g P g The role of photons in the subcell, in each cycle (AlGa) 1- e In e The thickness of As is 5nm to 300nm, Ga 1-e In e The thickness of As is 5nm to 300nm.

[0062] Ga 1-f In f As 1-g P gThe subcell includes a p-type doped base layer, an unintentionally doped i-layer and an n-type doped emitter layer, wherein Ga 1-f In f As 1-g P g Base layer: 0≤f≤0.8, 0≤g≤1, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness 30nm~5000nm; the unintentionally doped i layer can be Ga 1-f In f As 1-g P g or Ga 1-y In y P material, 0.4≤y≤1, thickness 10nm~1000nm; the emission layer can be Ga 1-f In f As 1-g P g or Ga 1-y In y P material, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness 30nm~5000nm.

[0063] The third tunnel junction includes an n-type doped AlGaInP layer and a p-type doped AlGaInAs layer, wherein the dopant of the AlGaInP layer is Se or Te, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaInAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, and growth temperature is 450℃~700℃.

[0064] (AlGa) 1-h In h The P subcell includes a p-type doped base layer, an unintentionally doped i layer, and an n-type doped emitter layer, where 0.4≤h≤1, and the base layer doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3, thickness 30nm~5000nm; thickness of unintentionally doped i layer 10nm~1000nm; doping concentration of emitter layer 1×10 16 cm -3 ~1×10 19 cm -3 , thickness 30nm~5000nm.

[0065] Ga 1-j In j The As cap layer is n-type doped, where 0≤j≤0.5 and the doping concentration is 1×10 18 ~1×10 21 cm -3 , the thickness range is 50nm~500nm.

[0066] After the above structure is prepared by epitaxy, the upper and lower metal electrodes and the anti-reflection film of the battery are prepared according to the known battery device process.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A germanium-based gallium arsenide solar cell, characterized in that: From bottom to top, it includes: germanium substrate, GaInP nucleation layer, GaInAs buffer layer, first tunneling junction, Ga 1-a In a As lattice gradient buffer layer, (AlGa) which plays the role of stress regulation and distributed Bragg reflector 1-b In b As / Ga 1-b In b As first period structure overshoot layer, Ga 1-c In c As subcell, second tunnel junction, (AlGa) 1-d In d As / Ga 1-d In d As periodic structure lattice gradient layer, (AlGa) which plays the role of stress regulation and distributed Bragg reflector 1-e In e As / Ga 1-e In e As second periodic structure overshoot layer, Ga 1-f In f As 1-g P g Subcell, third tunnel junction, (AlGa) 1-h In h P subcell and Ga 1-j In j As cap layer; a lower electrode is provided on the germanium substrate, 1- j In j The As cap layer is provided with an upper electrode; wherein: the Ga 1-a In a The In component a of the As lattice gradient buffer layer changes gradually from 0 to c, 0 <c≤0.5,0.4≤x<1,0<f≤0.8,0<g<1,0.4≤y<1,0.4≤h<1,c≥d> 0, b≥c, e≤d, 0 <j≤0.5; The Ga 1-c In c The As subcell includes p-type doped Ga 1-c In c As base layer, an unintentionally doped i layer and an n-type doped emitter layer, wherein: Ga 1-c In c As base layer: doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; The unintentionally doped i-layer is Ga 1-c In c As or Ga 1-x In x P material, thickness is 10nm~1000nm; The emitter layer is Ga 1-c In c As or Ga 1-x In x P material, doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; The Ga 1-a In a The lattice constant of the As lattice graded buffer layer changes from matching the Ge substrate to matching the Ga 1- c In c As sub-battery matching; The (AlGa) 1-b In b As / Ga 1-b In b The In content of the overshoot layer of the first periodic structure of As is greater than that of Ga 1-c In c The In component of the As subcell, the (AlGa) 1-b In b As / Ga 1-b In b The number of periods of the As first periodic structure overshoot layer ranges from 2 to 20, and in each period (AlGa) 1-b In b The thickness of As is 5nm to 300nm, Ga 1-b In b The thickness of As is 5nm to 300nm; The Ga 1-f In f As 1-g P g The subcell includes a p-type doped base layer, an unintentionally doped i-layer and an n-type doped emitter layer, wherein: Ga 1-f In f As 1-g P g Base layer: doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; The unintentionally doped i-layer is Ga 1-f In f As 1-g P g or Ga 1-y In y P material, thickness is 10nm~1000nm; The emitter layer is Ga 1-f In f As 1-g P g or Ga 1-y In y P material, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness 30nm~5000nm; The (AlGa) 1-d In d As / Ga 1-d In d The In component of the As periodic structure lattice graded layer changes gradually, and the (AlGa) 1-d In d As / Ga 1-d In d The lattice constant of the As periodic structure lattice graded layer changes from 1-c In c The As subcell is graded to match the Ga 1-f In f As 1-g P g Subcells are matched, and each gradient is made of (AlGa) 1-d In d As / Ga 1- d In d As is composed of periodic structures, and the number of periods ranges from 2 to 20; The (AlGa) 1-e In e As / Ga 1-e In e The lattice constant of the overshoot layer of the second periodic structure of As is not greater than that of Ga 1-f In f As 1-g P g Lattice constant of subcell; (AlGa) 1-e In e As / Ga 1-e In e The number of periods of the overshoot layer of the second periodic structure of As ranges from 2 to 20, and in each period (AlGa) 1-e In e The thickness of As is 5nm to 300nm, Ga 1-e In e The thickness of As is 5nm to 300nm; The (AlGa) 1-h In h The P subcell includes a p-type doped base layer, an unintentionally doped i-layer and an n-type doped emitter layer; wherein: The base layer doping concentration is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; The thickness of the unintentionally doped i layer is 10nm to 1000nm; the doping concentration of the emitter layer is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; The Ga 1-j In j As cap layer is n-type doped Ga 1-j In j As, where the doping concentration is 1×10 18 ~1×10 21 cm -3 , the thickness range is 50nm~500nm.

2. A method for preparing a germanium-based gallium arsenide solar cell, characterized in that: include: S1. Using MOCVD technology to grow a GaInP nucleation layer on a P-type germanium substrate; wherein: the n-type dopant is Si or Se, the growth temperature is 450°C to 700°C, the thickness ranges from 20 to 500nm, and an n-type Ge layer is formed by diffusion of phosphorus atoms in the nucleation layer, and a germanium subcell is formed with the p-type germanium substrate; S2. Using MOCVD technology to grow a GaInAs buffer layer on the GaInP nucleation layer; wherein: the n-type dopant is Si or Se, the growth temperature is 500° C. to 750° C., and the thickness ranges from 100 to 2000 nm; S3, using MOCVD technology to grow a first tunnel junction on the GaInAs buffer layer; the first tunnel junction includes an n-type doped GaAs layer and a p-type doped AlGaAs layer, wherein: the dopant of the GaAs layer is Se or Te, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, growth temperature is 450℃~700℃; S4. Use MOCVD technology to grow Ga on the first tunnel junction 1-a In a As lattice gradient buffer layer; Ga 1-a In a The In component a of the As lattice gradient buffer layer gradually changes from 0 to c, and the p-type doping concentration is 1×10 17 cm -3 ~1×10 19 cm -3 The growth temperature is 600℃~750℃, and the lattice constant is gradually changed from matching the germanium substrate to matching the Ga 1-c In c As sub-battery matching; S5. Using MOCVD technology in Ga 1-a In a (AlGa) grown on the As lattice gradient buffer layer plays the role of stress regulation and distributed Bragg reflector 1-b In b As / Ga 1-b In b As first periodic structure overshoot layer; the (AlGa) 1-b In b As / Ga 1-b In b The doping concentration of the As overshoot layer in the first periodic structure is 1×10 17 ~1×10 19 cm -3 , the growth temperature is 600℃~750℃, and the In component is greater than the Ga 1-c In c In component of As subcell, (AlGa) 1-b In b As / Ga 1-b In b The number of periods of the As first periodic structure overshoot layer ranges from 2 to 20, and in each period (AlGa) 1-b In b The thickness of As is 5nm to 300nm, Ga 1-b In b The thickness of As is 5nm to 300nm; S6. Using MOCVD technology, grow Ga 1-b In b As / Ga 1-b In b As on the first-period structural overshoot layer of Ga 1-c In c As sub-cell; Ga 1-c In c As sub-cell includes a p-type doped Ga 1-c In c As base region layer, an unintentionally doped i-layer, and an n-type doped emitter region layer, where: in the Ga 1-c In c As base region layer: 0 < c ≤ 0.5, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30 nm to 5000 nm; the unintentionally doped i-layer is Ga 1-c In c As or Ga 1-x In x P material, 0.4 ≤ x < 1, thickness is 10 nm to 1000 nm; the emitter region layer is Ga 1-c In c As or Ga 1-x In x P material, 0.4 ≤ x < 1, doping concentration 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30 nm to 5000 nm; S7, using MOCVD technology in Ga 1-c In c The second tunnel junction is grown on the As subcell; the second tunnel junction includes an n-type doped AlGaInP layer and a p-type doped AlGaInAs layer, wherein the dopant of the AlGaInP layer is Se or Te, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaInAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, growth temperature is 450℃~700℃; S8, using MOCVD technology to grow (AlGa) on the second tunnel junction 1-d In d As / Ga 1-d In d As periodic structure lattice gradient layer; (AlGa) 1-d In d As / Ga 1-d In d The In component of the As periodic structure lattice gradient layer is a gradient gradient change, and the (AlGa) 1-d In d As / Ga 1-d In d The lattice constant of the As periodic structure lattice graded layer changes from 1-c In c As subcells are gradually matched to Ga 1-f In f As 1-g P g Subcell matching, the range of variation is c≥d>0, each gradient of variation is (AlGa) 1- d In d As / Ga 1-d In d As is composed of periodic structures, and the number of periods ranges from 2 to 20; S9, using MOCVD technology in (AlGa) 1-d In d As / Ga 1-d In d (AlGa) grown on the As periodic structure lattice gradient layer plays the role of stress regulation and distributed Bragg reflector 1-e In e As / Ga 1-e In e As second periodic structure overshoot layer; the growth temperature is 600℃~750℃, and its lattice constant is not greater than Ga 1-f In f As 1-g P g Lattice constant of subcell, e≤d, (AlGa) 1-e In e As / Ga 1-e In e The number of periods of the overshoot layer of the second periodic structure of As ranges from 2 to 20, and in each period (AlGa) 1-e In e The thickness of As is 5nm to 300nm, Ga 1-e In e The thickness of As is 5nm to 300nm; S10. Using MOCVD technology to grow Ga 1-e In e As / Ga 1-e In e As on the second-period structural overshoot layer of Ga 1- f In f As 1-g P g sub-cell; Ga 1-f In f As 1-g P g sub-cell includes a p-type doped base region layer, an unintentionally doped i-layer, and an n-type doped emitter region layer. In the Ga 1-f In f As 1-g P g base region layer: 0 < f ≤ 0.8, 0 < g < 1, doping concentration 1 × 10 16 cm -3 ~1 × 10 19 cm -3 , thickness 30 nm to 5000 nm; the unintentionally doped i-layer is Ga 1-f In f As 1-g P g or Ga 1-y In y P material, 0.4 ≤ y < 1, thickness 10 nm to 1000 nm; the emitter region layer is Ga 1-f In f As 1-g P g or Ga 1-y In y P material, doping concentration 1 × 10 16 cm -3 ~1 × 10 19 cm -3 , thickness 30 nm to 5000 nm; S11, using MOCVD technology in Ga 1-f In f As 1-g P g The third tunnel junction is grown on the subcell; the third tunnel junction includes an n-type doped AlGaInP layer and a p-type doped AlGaInAs layer, and the dopant of the AlGaInP layer is Se or Te with a doping concentration of 1×10 19 ~1×10 21 cm -3 , the thickness range is 5nm~50nm, the growth temperature is 450℃~700℃; the dopant of AlGaInAs layer is Zn or C, and the doping concentration is 1×10 19 ~1×10 21 cm -3 , thickness range is 5nm~50nm, growth temperature is 450℃~700℃; S12, using MOCVD technology to grow (AlGa) on the third tunnel junction 1-h In h P subcell; (AlGa) 1-h In h The P subcell includes a p-type doped base layer, an unintentionally doped i layer, and an n-type doped emitter layer. 0.4≤h<1, and the doping concentration of the base layer is 1×10 16 cm -3 ~1×10 19 cm -3 , with a thickness of 30nm to 5000nm; the thickness of the unintentionally doped i layer is 10nm to 1000nm; the doping concentration of the emitter layer is 1×10 16 cm -3 ~1×10 19 cm -3 , thickness is 30nm~5000nm; S13. Growing an n-type doped Ga 1-h In h P sub-cell using MOCVD technology, with 0 < j ≤ 0.5, a doping concentration of 1×10 1-j In j As cap layer; 0 < j ≤ 0.5, doping concentration is 1×10 18 ~1×10 21 cm -3 , and the thickness ranges from 50 nm to 500 nm; S14, preparing the upper metal electrode, the lower metal electrode and the anti-reflection film of the battery.

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