Multi-junction flexible gallium arsenide laser cell with radiation resistance and preparation method thereof

Abstract

The invention discloses an anti-radiation multi-junction flexible gallium arsenide laser cell and a preparation method thereof, and the outer edge structure comprises a substrate, and a GaAs buffer layer, an N-layer GaInP barrier gradient layer, a lower cap layer, a GaInP window layer, a GaInAs contact layer, an N-junction GaInAs sub-cell and an upper cap layer which are sequentially disposed on the GaAs substrate. An AlGaInAs tunnel junction and a GaInP window layer are arranged between every two adjacent GaInAs sub-cells from bottom to top, and a Bragg reflector (DBR) is arranged between the (N-1) th GaInAs sub-cell and the (N-1) th AlGaInAs tunnel junction. A metal reflector (ODR) is prepared by PECVD or PVD to serve as a supporting layer of an epitaxial material and a conductive layer of the laser cell, so that the thickness of the laser cell can be obviously reduced, the conductivity of the laser cell is enhanced, and relatively small series resistance is easy to obtain. And photons which are not absorbed by the previous (N-1) th junction GaInAs sub-cells can be reflected back to the Nth junction GaInAs sub-cell, and meanwhile, the thickness of an active region of the Nth junction GaInAs sub-cell is reduced, so that the anti-radiation capability of the whole cell is improved.

Description

Technical Field

[0001] This invention relates to the field of laser battery technology, and in particular to a radiation-resistant multi-junction flexible gallium arsenide laser battery and its preparation method. Background Technology

[0002] Laser photovoltaic cells convert laser energy into electrical energy using the photovoltaic effect, and their performance directly affects the link efficiency and transmission power of laser power supply systems. Laser wireless power transmission has the advantages of long transmission distance, high transmission efficiency, and high power density.

[0003] Currently, 808nm GaAs multi-junction laser cells have a certain market presence in the terrestrial high-voltage field. Unlike the application of 808nm GaAs laser photovoltaic cells in wireless power transmission in terrestrial environments, 1064nm laser cells will be the next key research product for long-distance wireless charging and low-loss applications. Furthermore, in the space environment, laser cells are subjected to significant high-energy particle radiation, causing ionization and displacement damage within the cells, leading to severe degradation of their electrical performance and significantly hindering practical applications. Combined with irradiation theory studies of space solar cells, gallium arsenide solar cells exhibit poor radiation resistance. The main reason for the performance degradation after irradiation is that displacement damage creates defects within the semiconductor material, forming non-radiative recombination centers and reducing the minority carrier lifetime of the cell.

[0004] Therefore, the radiation resistance of laser batteries under space environment conditions is of great significance for efficient and high-power laser wireless power transmission in special environments. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies in existing technologies by providing a radiation-resistant, multi-junction flexible gallium arsenide laser cell. This cell features high photoelectric conversion efficiency, radiation resistance, and shapeability, and can be directly used as a complete battery. Another object of the present invention is to provide a method for preparing the above-mentioned laser battery.

[0006] The technical solution adopted to achieve the purpose of this invention is: A radiation-resistant multi-junction flexible gallium arsenide laser cell, the outer structure of which includes a substrate, and sequentially disposed on the GaAs substrate a GaAs buffer layer, an N-layer GaInP barrier gradient layer, a lower cap layer, a GaInP window layer, an N-junction GaInAs sub-cell, and an upper cap layer. An AlGaInAs tunnel junction and a GaInP window layer are disposed between adjacent GaInAs sub-cells from bottom to top. A Bragg reflector (DBR) is disposed between the (N-1)th GaInAs sub-cell and the (N-1)th AlGaInAs tunnel junction, wherein: Each GaInAs sub-cell comprises an n-type doped n-GaInP emitter region and a p-type doped p-GaInAs base region, or an n-GaInAs emitter region and a p-type doped p-GaInAs base region.

[0007] In the above technical solution, the GaInP barrier gradient layer is an n-type doped Ga... 1-z In z The GaInP barrier gradient layer, which serves as both a barrier layer and a lattice gradient layer, can reduce the cost of epitaxial fabrication. The doping concentration of the GaInP barrier gradient layer is 1×10⁻⁶. 17 ~1×10 19 cm -3 The thickness ranges from 50nm to 500nm.

[0008] In the above technical solution, the GaInAs contact layer is n-type doped Ga. 1-x In x As contact layer, where 0.19 ≤ x ≤ 0.3, and the doping concentration is 1 × 10⁻⁶. 18 ~1×10 21 cm -3 The thickness is 50nm~500nm.

[0009] In the above technical solution, the first junction tunnel junction or the Nth junction tunnel junction includes n-type doped n+-(Al) c Ga 1-c ) 1-x In x As layer and p-type doped p+-(Al) c Ga 1-c ) 1-x In x As layer, where 0≤c≤0.5, 0.5≤d≤1 and 0.19≤x≤0.3, n-type doped n+-(Al c Ga 1-c ) 1-x In x As layer and p-type doped p+-(Al) c Ga 1-c ) 1-x In x The As layer doping concentration is 1×10⁻⁶. 19 -1×10 20 cm -3 Their thicknesses are all 1-100nm.

[0010] In the above technical solution, the thickness of the GaInAs sub-cell at the first junction or the GaInAs sub-cell at the Nth junction is 30-3000 nm, and its doping concentration is 1×10⁻⁶. 17 -1×1019 cm -3 ,N≧1.

[0011] In the above technical solution, the thickness of each layer of the laser cell is obtained by the following formula (Beer-Lambert's law): in, I 0 represents the light intensity on the surface of the laser cell. x It is the transmission depth of the incident laser. I It is the intensity of the incident laser light transmitted to point x. α (λ) λ represents the absorption coefficient of the GaInAs sub-cell in the absorption region at wavelength λ.

[0012] In the above technical solution, the Bragg reflector DBR is (Al) c Ga 1-c ) 1-x In x As / (Al d Ga 1-d ) 1- x In x As a DBR, where 0≤c≤0.5, 0.5≤d≤1, and 0.19≤x≤0.3, the Bragg reflector DBR is p-type doped with a doping concentration of 1×10⁻⁶. 17 -1×10 19 cm -3 The thickness is 1000-4000 nm, the number of periods is 10-30, and within each period, (Al) c Ga 1-c ) 1-x In x The thickness of As is 20-200 nm, (Al) d Ga 1-d ) 1-x In x The thickness of As is 20-200nm, which can reflect photons that pass through the (N-1)th junction Ga(In)As sub-cell and be reabsorbed by the (N-1)th junction Ga(In)As sub-cell. By adjusting the thickness, specific reflection of a certain wavelength can be achieved, with spectral reflection of 20-100% of the characteristic wavelengths, thereby improving quantum efficiency and radiation resistance.

[0013] Another aspect of the present invention includes a method for fabricating the multi-junction flexible gallium arsenide laser cell, comprising the following steps: Step 1: Using metal-organic chemical vapor deposition (MOCVD), GaAs buffer layer, N-layer GaInP barrier gradient layer, lower cap layer, GaInP window layer, N-junction GaInAs subcell and upper cap layer are sequentially grown on GaAs substrate. An AlGaInAs tunnel junction and GaInP window layer are set between two adjacent GaInAs subcells from bottom to top. A Bragg reflector (DBR) is set between the (N-1)th GaInAs subcell and the (N-1)th AlGaInAs tunnel junction. Step 2: Deposit an ODR (Optical Discharge Reflector) on the upper cap layer, electroplate GaAs substrate material, adhere a glass cover to the GaAs substrate, remove the GaAs substrate, GaAs buffer layer, and GaInP blocking gradient layer, photolithographically fabricate the upper electrode, etch the lower cap layer, and deposit an antireflection film material to complete the fabrication of the laser cell. 1-z In z The P-blocking layer is removed by etching of the gradient layer, reducing the series resistance of the flexible laser cell.

[0014] In the above technical solution, a metal reflector (ODR) is deposited using PECVD or PVD equipment as the support layer for the epitaxial material and the conductive layer for the laser cell. The main purpose is to reflect any light not fully absorbed by the first N-1 junction GaInAs sub-cell to the Nth junction GaInAs sub-cell, achieving good photon reflection. Simultaneously, this layer also serves as the metal contact layer for the lower electrode material. The fabrication of the metal reflector effectively reduces the thickness of the Nth junction GaInAs sub-cell, lowers the series resistance of the cell, and ensures excellent power output of the laser cell under high-power incident light conditions, while maintaining good fill factor and other performance characteristics.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Compared with traditional forward multi-junction gallium arsenide laser cells, the multi-junction gallium arsenide laser cell of the present invention has a thinner overall thickness after removing the GaInP blocking gradient layer during the device fabrication process, which is beneficial to improving the heat dissipation performance of the laser cell at high power. At the same time, the shaping capability of the flexible laser cell is enhanced, which can meet the requirements of bending in special dimensions.

[0016] 2. By adjusting the position of the center wavelength of the DBR (Distributed Bragg Reflector), the Ga2 phase transmitted through the N-1 junction solar cell can be reflected. 1- x In x As the photons of the cell, the sub-cell reabsorption is enhanced, which improves the quantum efficiency. At the same time, increasing the thickness of the DBR layer can reduce the thickness of the active region of the PN junction of the cell, which helps to improve the radiation resistance of the cell.

[0017] 3. The device fabrication process utilizes PECVD or PVD to fabricate an optical deflector (ODR) as a support layer for the epitaxial material and a conductive layer for the laser cell. This significantly reduces the thickness of the laser cell, enhances its conductivity, and easily achieves a lower series resistance. Furthermore, it can reflect photons not absorbed by the first N-1 junction GaInAs sub-cells back to the Nth junction GaInAs sub-cell, simultaneously reducing the active region thickness of the Nth junction GaInAs sub-cell, thereby improving the overall cell's radiation resistance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the laser battery structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the GaInP gradient barrier layer in Example 1. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] Example 1 like Figures 1-2 As shown, a radiation-resistant multi-junction flexible gallium arsenide laser cell includes a substrate, and GaAs buffer layer, N-layer GaInP barrier gradient layer, lower cap layer, GaInP window layer, N-junction GaInAs sub-cell and upper cap layer sequentially disposed on the GaAs substrate. An AlGaInAs tunnel junction and GaInP window layer are disposed from bottom to top between two adjacent GaInAs sub-cells. A Bragg reflector (DBR) is disposed between the (N-1)th GaInAs sub-cell and the (N-1)th AlGaInAs tunnel junction. Each GaInAs sub-cell includes an n-type doped n-GaInP emitter region and a p-type doped p-GaInAs base region, or an n-GaInAs emitter region and a p-type doped p-GaInAs base region.

[0022] Furthermore, the GaAs buffer layer has an n-type dopant of Si, Se, or Te, with a doping concentration of 1 × 10⁻⁶. 17 ~1×10 19 cm -3 The growth temperature is 600–750℃, and the thickness range is 100–1000nm.

[0023] Furthermore, the GaInP barrier gradient layer has an n-type dopant of Si, Se, or Te, with a doping concentration of 1 × 10⁻⁶. 17 ~1×10 19 cm -3The growth temperature is 600–750℃, and the thickness range is 50nm~500nm.

[0024] Furthermore, the GaInAs contact layer has an n-type dopant of Si, Se, or Te, with a doping concentration of 1 × 10⁻⁶. 18 ~1×10 21 cm -3 The growth temperature is 550–700℃, and the thickness ranges from 50nm to 500nm.

[0025] Furthermore, the tunnel junction in the first junction comprises n-type doped n+-(Al) c Ga 1-c ) 1-x In x As layer and p-type doped p+-(Al) c Ga 1-c ) 1-x In x As layer, where 0≤c≤0.5, 0.5≤d≤1 and 0.19≤x≤0.3, n+-(Al) c Ga 1-c ) 1- x In x The As layer is doped with Si, Se, or Te, with a doping concentration of 1 × 10⁻⁶. 19 -1×10 21 cm -3 , and p+-(Al c Ga 1-c ) 1-x In x The As layer is doped with Zn, Mg, or C, with a doping concentration of 1×10⁻⁶. 19 -1×10 20 cm -3 The thickness ranges from 1 to 100 nm.

[0026] Furthermore, the tunnel junction of the second junction comprises n-type doped n+-(Al) c Ga 1-c ) 1-x In x As layer and p-type doped p+-(Al) c Ga 1-c ) 1-x In x As layer, where 0≤c≤0.5, 0.5≤d≤1 and 0.19≤x≤0.3, n+-(Al) c Ga 1-c ) 1- x In xThe As layer is doped with Si, Se, or Te, with a doping concentration of 1 × 10⁻⁶. 19 -1×10 21 cm -3 , and p+-(Al c Ga 1-c ) 1-x In x The As layer is doped with Zn, Mg, or C, with a doping concentration of 1×10⁻⁶. 19 -1×10 20 cm -3 The thickness ranges from 1 to 100 nm.

[0027] Furthermore, the Nth junction tunnel junction includes n-type doped n+-(Al) c Ga 1-c ) 1-x In x As layer and p-type doped p+-(Al) c Ga 1-c ) 1-x In x As layer, where 0≤c≤0.5, 0.5≤d≤1 and 0.19≤x≤0.3, n+-(Al) c Ga 1-c ) 1-x In x The As layer is doped with Si, Se, or Te, with a doping concentration of 1 × 10⁻⁶. 19 -1×10 21 cm -3 , and p+-(Al c Ga 1-c ) 1-x In x The As layer is doped with Zn, Mg, or C, with a doping concentration of 1×10⁻⁶. 19 -1×10 20 cm -3 The thickness ranges from 1 to 100 nm.

[0028] Furthermore, the GaInAs sub-cell described in the first junction is Ga... 1-x In x As batteries, including n-type doped n-Ga 1- x In x As emitter layer and p-type doped p-Ga 1-x In x As-based layer, wherein 0.19 ≤ x ≤ 0.3, and growth temperature is 600–800℃; wherein the n-Ga 1-x In x The As emitter layer is doped with Si, Se, or Te, and the doping concentration is 1 × 10⁻⁶.16 -1×10 18 cm -3 The thickness ranges from 50 to 300 nm; the p-Ga 1-x In x The As base layer is doped with Zn, Mg, or C, with a doping concentration of 1 × 10⁻⁶. 17 -1×10 19 cm -3 The thickness ranges from 30 to 3000 nm.

[0029] Furthermore, the second GaInAs sub-cell is Ga 1-x In x As batteries, including n-type doped n-Ga 1- x In x As emitter layer and p-type doped p-Ga 1-x In x As-based layer, wherein 0.19 ≤ x ≤ 0.3, and growth temperature is 600–800℃; wherein the n-Ga 1-x In x The As emitter layer is doped with Si, Se, or Te, and the doping concentration is 1 × 10⁻⁶. 16 -1×10 18 cm -3 The thickness ranges from 50 to 300 nm; the p-Ga 1-x In x The As base layer is doped with Zn, Mg, or C, with a doping concentration of 1 × 10⁻⁶. 17 -1×10 19 cm -3 The thickness ranges from 30 to 3000 nm.

[0030] Furthermore, the GaInAs sub-cell of the (N-1)th junction is Ga 1-x In x As batteries, including n-type doped n-Ga 1- x In x As emitter layer and p-type doped p-Ga 1-x In x As-based layer, wherein 0.19 ≤ x ≤ 0.3, and growth temperature is 600–800℃; wherein the n-Ga 1-x In x The As emitter layer is doped with Si, Se, or Te, and the doping concentration is 1 × 10⁻⁶. 16 -1×10 18 cm -3 The thickness ranges from 50 to 300 nm; the p-Ga 1-x Inx The As base layer is doped with Zn, Mg, or C, with a doping concentration of 1 × 10⁻⁶. 17 -1×10 19 cm -3 The thickness ranges from 30 to 3000 nm.

[0031] Furthermore, the GaInAs sub-cell of the Nth junction is Ga 1-x In x As batteries, including n-type doped n-Ga 1-x In x As emitter layer and p-type doped p-Ga 1-x In x As-based layer, wherein 0.19 ≤ x ≤ 0.3, and growth temperature is 600–800℃; wherein the n-Ga 1-x In x The As emitter layer is doped with Si, Se, or Te, and the doping concentration is 1 × 10⁻⁶. 16 -1×10 18 cm -3 The thickness ranges from 50 to 300 nm; the p-Ga 1-x In x The As base layer is doped with Zn, Mg, or C, with a doping concentration of 1 × 10⁻⁶. 17 -1×10 19 cm -3 The thickness ranges from 30 to 3000 nm.

[0032] Furthermore, the Bragg reflector DBR is (Al) c Ga 1-c ) 1-x In x As / (Al d Ga 1-d ) 1-x In x As DBR, where 0≤c≤0.5, 0.5≤d≤1, and 0.19≤x≤0.3, the dopant is Zn, Mg, or C, and the doping concentration is 1×10⁻⁶. 17 -1×10 19 cm -3 The thickness ranges from 1000 to 4000 nm, and the number of periods is 10 to 30. Within each period, (Al) c Ga 1-c ) 1-x In x The thickness range of As is 20-200 nm, (Al) d Ga 1-d ) 1-x In xThe thickness of As ranges from 20 to 200 nm, and the growth temperature is 600–800 °C.

[0033] Furthermore, the GaInP window layer is Ga 1-z In z P, where 0.4 ≤ z ≤ 0.9, the dopant is Si, Se or Te, and the doping concentration is 1 × 10⁻⁶. 16 -5×10 18 cm -3 The thickness ranges from 50 to 4000 nm, and the growth temperature is 600–800℃.

[0034] Furthermore, the upper cap layer is n-type doped Ga. 1-x In x As, where 0.19 ≤ x ≤ 0.3, the dopant is Zn, Mg or C, and the doping concentration is 1 × 10⁻⁶. 18 -1×10 21 cm -3 The thickness ranges from 50nm to 500nm, and the growth temperature is 550–700℃.

[0035] Example 2 This embodiment provides a method for fabricating a radiation-resistant multi-junction flexible gallium arsenide laser cell as described in Embodiment 1, comprising the following steps: Step 1: Using metal-organic chemical vapor deposition (MOCVD), GaAs buffer layer, N-layer GaInP barrier gradient layer, lower cap layer, GaInP window layer, N-junction GaInAs subcell and upper cap layer are sequentially grown on GaAs substrate. An AlGaInAs tunnel junction and GaInP window layer are set between two adjacent GaInAs subcells from bottom to top. A Bragg reflector (DBR) is set between the (N-1)th GaInAs subcell and the (N-1)th AlGaInAs tunnel junction.

[0036] Step 2: Deposit a contact metal reflector (ODR) on the upper cap layer, electroplate GaAs substrate material, glue a glass cover on the GaAs substrate, remove the GaAs substrate, GaAs buffer layer and GaInP blocking gradient layer, photolithography and fabricate the upper electrode, etch the lower cap layer, deposit antireflection film material, and complete the fabrication of the laser cell.

[0037] The top cap layer is n-type doped Ga. 1-x In x As, where 0.19 ≤ x ≤ 0.3, the dopant is Zn, Mg or C, and the doping concentration is 1 × 10⁻⁶. 18 -1×10 21 cm -3 The thickness ranges from 50nm to 500nm, and the growth temperature is 550–700℃.

[0038] The total time required for the growth of the above-mentioned material layers is 3-6 hours, after which the reverse device process can be used.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A radiation-resistant, multi-junction flexible gallium arsenide laser cell, characterized in that, The outer structure of the multi-junction flexible gallium arsenide laser cell includes a substrate, and sequentially disposed on the GaAs substrate a GaAs buffer layer, an N-layer GaInP barrier gradient layer, a lower cap layer, a GaInP window layer, an N-junction GaInAs sub-cell, and an upper cap layer. An AlGaInAs tunnel junction and a GaInP window layer are disposed between adjacent GaInAs sub-cells from bottom to top. A Bragg reflector (DBR) is disposed between the (N-1)th GaInAs sub-cell and the (N-1)th AlGaInAs tunnel junction. Each GaInAs sub-cell comprises an n-type doped n-GaInP emitter region and a p-type doped p-GaInAs base region, or an n-GaInAs emitter region and a p-type doped p-GaInAs base region.

2. The multi-junction flexible gallium arsenide laser cell according to claim 1, characterized in that, Each GaInP barrier gradient layer is an n-type doped Ga. 1-z In z The GaInP barrier gradient layer has a doping concentration of 1×10⁻⁶. 17 ~1×10 19 cm -3 The thickness ranges from 50nm to 500nm.

3. The multi-junction flexible gallium arsenide laser cell according to claim 1, characterized in that, The GaInAs contact layer is n-type doped Ga. 1-x In x As contact layer, where 0.19 ≤ x ≤ 0.3, and the doping concentration is 1 × 10⁻⁶. 18 ~1×10 21 cm -3 The thickness is 50nm~500nm.

4. The multi-junction flexible gallium arsenide laser cell according to claim 1, characterized in that, The first junction tunnel junction or the Nth junction tunnel junction includes n-type doped n+-(Al) c Ga 1-c ) 1-x In x As layer and p-type doped p+-(Al) c Ga 1-c ) 1-x In x As layer, where 0≤c≤0.5, 0.5≤d≤1 and 0.19≤x≤0.3, n-type doped n+-(Al c Ga 1-c ) 1-x In x As layer and p-type doped p+-(Al) c Ga 1-c ) 1-x In x The As layer doping concentration is 1×10⁻⁶. 19 -1×10 20 cm -3 Their thicknesses are all 1-100nm.

5. The multi-junction flexible gallium arsenide laser cell according to claim 1, characterized in that, The thickness of the GaInAs sub-cell in the first junction or the GaInAs sub-cell in the Nth junction is 30-3000 nm, and its doping concentration is 1×10⁻⁶. 17 -1×10 19 cm -3 ,N≧1.

6. The multi-junction flexible gallium arsenide laser cell according to claim 1, characterized in that, The thickness of all layers in the epitaxial structure of the multi-junction flexible gallium arsenide laser cell is obtained by the following formula: in, I 0 represents the light intensity on the surface of the laser cell. x It is the transmission depth of the incident laser. I It is the intensity of the incident laser light transmitted to point x. α (λ) λ represents the absorption coefficient of the GaInAs sub-cell in the absorption region at wavelength λ.

7. The multi-junction flexible gallium arsenide laser cell according to claim 1, characterized in that, The Bragg reflector DBR is (Al) c Ga 1-c ) 1-x In x As / (Al d Ga 1-d ) 1-x In x As DBR, where 0≤c≤0.5, 0.5≤d≤1 and 0.19≤x≤0.

3.

8. The multi-junction flexible gallium arsenide laser cell according to claim 7, characterized in that, The Bragg reflector DBR is p-type doped with a doping concentration of 1×10⁻⁶. 17 -1×10 19 cm -3 The thickness is 1000-4000 nm, the number of periods is 10-30, and within each period, (Al) c Ga 1-c ) 1-x In x The thickness of As is 20-200 nm, (Al) d Ga 1-d ) 1-x In x The thickness of As is 20-200nm.

9. The method for fabricating a multi-junction flexible gallium arsenide laser cell according to any one of claims 1 to 8, comprising the following steps: Step 1: Using metal-organic chemical vapor deposition (MOCVD), GaAs buffer layer, N-layer GaInP barrier gradient layer, lower cap layer, GaInP window layer, GaInAs contact layer, N-junction GaInAs subcell and upper cap layer are grown sequentially on GaAs substrate. An AlGaInAs tunnel junction and GaInP window layer are set between two adjacent GaInAs subcells from bottom to top. A Bragg reflector (DBR) is grown between the (N-1)th GaInAs subcell and the (N-1)th AlGaInAs tunnel junction. Step 2: Evaporate the contact metal reflector onto the upper cap layer, electroplate the GaAs substrate material, glue the glass cover onto the GaAs substrate, remove the GaAs substrate, GaAs buffer layer and GaInP blocking gradient layer, photolithographically etch and fabricate the upper electrode, etch the lower cap layer, and evaporate the antireflection film material to complete the fabrication of the laser cell.

10. The preparation method according to claim 9, characterized in that, Metal reflectors are deposited using PECVD or PVD equipment as a support layer for epitaxial materials and a conductive layer for laser cells.

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