A germanium-based indium gallium arsenide epitaxial layer structure and a defect control method and system thereof
By combining real-time monitoring and local repair, the problem of defect control in triple-junction solar cells has been solved, achieving efficient defect reduction and performance improvement, and significantly improving photoelectric conversion efficiency and cell performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGSHAN DEHUA CHIP TECH CO LTD
- Filing Date
- 2025-12-09
- Publication Date
- 2026-06-23
Smart Images
Figure CN122269810A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a germanium-based indium gallium arsenide epitaxial layer structure and its defect control method and system. Background Technology
[0002] Triple-junction and higher-order solar cells (such as InGaP / InGaAs / Ge structures) are currently the photovoltaic devices with the highest known photoelectric conversion efficiency. To break through their theoretical efficiency limit and reduce costs, combining wide-bandgap perovskite cells with high-efficiency III-V group cells to form tandem cells has become one of the most promising technological routes. Among these, combining a Ge / Ge bottom cell with a perovskite top cell is a feasible technical solution. However, existing technologies have the following problems:
[0003] 1) The "blind operation" defect in the growth process: Traditional MOCVD process lacks real-time and accurate monitoring of the strain state of epitaxial layers. After the process parameters are set, they cannot be dynamically adjusted according to the actual strain relaxation state, resulting in insufficient strain relaxation or premature dislocation generation, and poor process controllability.
[0004] 2) Post-processing "global thermal budget" limitations: Although conventional rapid thermal annealing (RTA) can repair some point defects, its global heating mode can lead to substrate overheating, element interdiffusion, and limited ability to repair extended dislocations. It may even introduce new defects due to thermal stress.
[0005] 3) Significant lattice mismatch: The lattice constant of the Ge substrate is 5.658 Å, while that of In... 0.11 GaAs (usually In) 0.11 Ga 0.89 The lattice constant of As or its neighboring components is typically greater than 5.653 Å, exhibiting a significant lattice mismatch (typically >0.5%) with Ge. This mismatch introduces a large number of penetrating dislocations into the InGaAs epitaxial layer, which become nonradiative recombination centers, severely reducing carrier lifetime and diffusion length.
[0006] 4) Mid-cell quality bottleneck: These high-density defects cause the open-circuit voltage and fill factor of the InGaAs mid-cell to be far lower than the theoretical values, becoming the performance bottleneck of the entire tandem cell. Even if the perovskite top cell performs well, the low-quality mid-cell will limit the overall current matching and efficiency.
[0007] 5) Series resistance problem: The defect exists not only in the active region, but also in the tunnel junction and window layer, which leads to an increase in the series resistance of the double junction cell and further deteriorates the fill factor. Summary of the Invention
[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a germanium-based indium gallium arsenide epitaxial layer structure and its defect control method and system.
[0009] To achieve the above objectives, the technical solution provided by this invention is as follows:
[0010] A method for controlling defects in germanium-based indium gallium arsenide epitaxial layer structures, including growth structure regulation and growth process regulation;
[0011] in,
[0012] Growth structure regulation includes:
[0013] Using a Ge cell as a substrate, an InGaP nucleation layer, an InGaAs buffer layer, an n-GaAs / p-GaAlAs bottom tunnel junction, a composite buffer layer, an InGaAlAs cell back field, an InGaAs cell, an InGaP window layer, and an n-InGaAs highly doped cap layer are sequentially grown on the Ge cell. The composite buffer layer includes a composition gradient layer and a dislocation filtering layer.
[0014] Growth process regulation includes:
[0015] A wafer curvature monitoring system integrated into the MOCVD reaction chamber was used to acquire stress evolution data in real time during the growth process of germanium-based indium gallium arsenide epitaxial layer structure;
[0016] During the growth of the composite buffer layer, the wafer curvature monitoring system feeds back the curvature data in the stress evolution data to the process controller in real time. The process controller compares the real-time curvature data with the preset ideal stress-time curve. When the real-time stress deviates from the preset ideal stress-time curve and exceeds the set threshold, the growth parameters are automatically adjusted so that the actual stress state of the germanium-based indium gallium arsenide epitaxial layer structure returns to the preset ideal stress-time curve.
[0017] After the epitaxial growth of the germanium-based indium gallium arsenide epitaxial layer structure is completed, it is taken out of the MOCVD reaction chamber. Then, a pulsed laser is used to scan and irradiate the entire surface of the germanium-based indium gallium arsenide epitaxial layer structure in an inert gas atmosphere, so that the extremely thin layer on the surface of the InGaAs cell is instantly melted and recrystallized to repair defects.
[0018] In this technical solution, the organic combination of "process monitoring and feedback" and "post-processing local repair" can realize the whole process control of defects in germanium-based indium gallium arsenide epitaxial layer structures from prevention to repair.
[0019] In addition, by inserting a special composite buffer layer between the Ge cell and the back field of the InGaAlAs cell, dislocations can be effectively filtered, significantly improving the crystal quality of the InGaAs cell, thereby greatly improving the fill factor and photoelectric conversion efficiency of the double-junction cell.
[0020] Furthermore, the composition-gradient layer is located above the tunnel junction in the n-GaAs / p-GaAlAs substrate, and is In x Ga 1- x Al k As composition graded layer, where x increases in steps from 0.01 to 0.15, eventually matching the lattice constant of the back field of the cell in InGaAlAs; k takes values from 0.15 to 0.4;
[0021] The dislocation filter layer is located above the composition-gradient layer and is a strained superlattice structure composed of multiple pairs of In. y Ga 1-y As / In z Ga 1-z As is formed by alternating layers, y takes values of 0.09-0.12, and z takes values of 0.0-0.08.
[0022] Furthermore, the thickness of the component gradient layer is 1.0-3.0 μm.
[0023] Furthermore, the strained superlattice structure of the dislocation filtering layer is In 0.1 Ga 0.9 As / GaAs superlattice pairs, or In 0.12 Ga 0.88 As / In 0.08 Ga 0.92 As superlattice pairs.
[0024] Furthermore, the growth parameters include trimethylindium flow rate, system V / III ratio, growth temperature, and growth rate.
[0025] Furthermore, the InGaAs cell includes a p-InGaAs base region and an n-InGaAs emitter region, and the total thickness of the p-InGaAs base region, the n-InGaAs emitter region, and the back field of the InGaAlAs cell is 1800~2500nm.
[0026] Furthermore, the pulsed laser emitted by the pulsed laser is a KrF excimer laser with a wavelength of 248 nm, a pulse width of 10–50 ns, and an energy density of 0.3–0.8 J / cm². 2 .
[0027] Furthermore, to achieve the above objectives, the present invention also provides a defect control system for germanium-based indium gallium arsenide epitaxial layer structures, used to implement the above-mentioned defect control method for germanium-based indium gallium arsenide epitaxial layer structures, comprising:
[0028] MOCVD reaction chamber;
[0029] The wafer curvature monitoring system integrated into the MOCVD reaction chamber is used to acquire stress evolution data of germanium-based indium gallium arsenide epitaxial layer structure in real time;
[0030] The process controller is used to receive stress evolution data of the germanium-based indium gallium arsenide epitaxial layer structure and compare it with a preset ideal stress-time curve. When the deviation exceeds a set threshold, a control signal is output.
[0031] The actuator automatically adjusts the growth parameters according to the control signal;
[0032] Pulsed laser processing station, providing an inert gas atmosphere and pulsed laser;
[0033] A pulsed laser is used to scan and irradiate the entire surface of a germanium-based indium gallium arsenide epitaxial layer structure in an inert gas atmosphere, causing the extremely thin layer on the surface of the InGaAs cell to melt and recrystallize instantly to repair defects.
[0034] Furthermore, the present invention also provides a germanium-based indium gallium arsenide epitaxial layer structure, which is prepared using the above-mentioned defect control method for germanium-based indium gallium arsenide epitaxial layer structures. It includes a Ge cell, an InGaP nucleation layer, an InGaAs buffer layer, an n-GaAs / p-GaAlAs bottom tunnel junction, a composite buffer layer, an InGaAlAs cell back field, an InGaAs cell, an InGaP window layer, and an n-InGaAs highly doped cap layer, wherein the composite buffer layer includes a composition gradient layer and a dislocation filtering layer.
[0035] Furthermore, the present invention also provides a solar cell comprising the aforementioned germanium-based indium gallium arsenide epitaxial layer structure.
[0036] Compared with existing technologies, the principles and advantages of this technical solution are as follows:
[0037] 1. Significantly Reduced Defect Density: During the growth of the composite buffer layer, the growth parameters are automatically adjusted by combining a wafer curvature monitoring system and a process controller, achieving "optimal growth" and reducing the generation of macroscopic dislocation networks from the source. Furthermore, a pulsed laser is used to scan and irradiate the entire surface of the germanium-based indium gallium arsenide epitaxial layer structure in an inert gas atmosphere, causing the extremely thin layer on the surface of the InGaAs cell to melt and recrystallize instantaneously. This "precision surgery" on residual defects eliminates microscopic dislocations that could not be avoided in the previous step. Combined with structural optimization of the composite buffer layer, the penetration dislocation density in the GaInAs active region can be reduced to 10-1. 5 cm -2 The following levels, compared to traditional technology (approximately 2×10), 7 cm -2 This represents an improvement of nearly three orders of magnitude.
[0038] 2. Significantly Improved Device Performance: The extremely low defect density significantly suppresses non-radiative recombination, greatly improving the open-circuit voltage and carrier collection efficiency of the mid-cell. The high-quality crystal structure enhances the electrical performance of the tunnel junction and interfaces in the GaAs / p-GaAlAs substrate, reducing series resistance and facilitating efficient carrier transport. Experimental data show that the fill factor increased from 74.6% to 80.1%, the open-circuit voltage increased from 1091mV to 1127mV, and the photoelectric conversion efficiency increased from 15.55% to 22.02%.
[0039] 3. Precise and controllable thermal budget: Pulsed laser annealing uses extremely short pulses (nanosecond level) and extremely thin layers (≤50nm) to achieve local repair of defects, avoiding substrate overheating, element interdiffusion and thermal stress problems caused by traditional RTA global heating.
[0040] 4. Enhanced process controllability and repeatability: In-situ strain monitoring enables closed-loop feedback control, real-time correction of growth deviations, improved batch-to-batch consistency, and reduced process debugging costs and time.
[0041] 5. Outstanding synergistic effect: The germanium-based indium gallium arsenide epitaxial layer structure after the insertion of the composite buffer layer, in-situ monitoring, and laser repair enhance each other, producing a "1+1>2" effect, which can overcome the limitations of single technical means. Attached Figure Description
[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the services required in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0043] Figure 1 This is a schematic diagram of the germanium-based indium gallium arsenide epitaxial layer structure in an embodiment of the present invention;
[0044] Figure 2 The results of X-ray diffraction tests on the samples of Example 1 and Comparative Example 1 are shown in the figure.
[0045] Figure 3 The diagram shows the apparent defects of Comparative Example 1.
[0046] Figure 4 This is a diagram of the apparent defects in Example 1. Detailed Implementation
[0047] The present invention will be further described below with reference to specific embodiments:
[0048] This embodiment describes a method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure, which includes growth structure regulation and growth process regulation.
[0049] in,
[0050] Growth structure regulation includes:
[0051] Using a Ge cell as a substrate, an InGaP nucleation layer, an InGaAs buffer layer, an n-GaAs / p-GaAlAs bottom tunnel junction, a composite buffer layer, an InGaAlAs cell back field, an InGaAs cell, an InGaP window layer, and an n-InGaAs highly doped cap layer are sequentially grown on the Ge cell. The composite buffer layer includes a composition gradient layer and a dislocation filtering layer.
[0052] Growth process regulation includes:
[0053] A wafer curvature monitoring system integrated into the MOCVD reaction chamber was used to acquire stress evolution data in real time during the growth process of germanium-based indium gallium arsenide epitaxial layer structure (i.e., the structure corresponding to growth structure regulation).
[0054] During the growth process, the growth temperature of the GaInP nucleation layer is 580~610℃, and the growth thickness is 3~15nm; the growth temperature of the GaInAs buffer layer is 610~640℃, and the growth thickness is 300~700nm; the growth temperature of the n-GaAs / p-GaAlAs under-substrate tunnel junction is 550~570℃, where the GaAs growth thickness is 10~20nm and the AlGaAs growth thickness is 5~20nm; In x Ga 1-x Al k The growth temperature of the As composition graded layer is 620~660℃, the thickness of each layer is 150~300nm, x=0.01~0.15, k=0.15~0.4, and the number of layers is 5~20; In y Ga 1-y As / In z Ga 1-z The growth temperature of the As dislocation filter layer is 620~660℃, the number of periods is 5-20 pairs, the thickness of each layer is 50-200nm, y=0.09~0.12, z=0.0~0.08; the growth temperature of the back field of the InGaAlAs cell, the p-InGaAs base region and the n-InGaAs emitter region is 620~660℃, and the total thickness is 1800~2500nm; the growth temperature of the GaInP window layer is 620~660℃, and the total thickness is 25~200nm; the growth temperature of the n-InGaAs highly doped cap layer is 620~660℃, and the total thickness is 50~200nm.
[0055] During the growth of the composite buffer layer, the wafer curvature monitoring system feeds back the curvature data from the stress evolution data to the process controller in real time. The process controller compares the real-time curvature data with the preset ideal stress-time curve. When the real-time stress deviates from the preset ideal stress-time curve and exceeds a set threshold, the growth parameters are automatically adjusted to bring the actual stress state of the germanium-based indium gallium arsenide epitaxial layer structure back to the preset ideal stress-time curve. This includes: when the DRT curve of the wafer curvature monitoring system detects large fluctuations and spikes, indicating that the stress relaxation rate is too fast (indicating rapid dislocation generation), the process controller automatically fine-tunes the TMI flow rate and As alkyl flow rate, adjusts the V / III ratio of the system, and slightly lowers the growth temperature (-3~-5℃) to make the strain relaxation process smoother and more closely follow the preset ideal stress-time curve.
[0056] After the epitaxial growth of the germanium-based indium gallium arsenide (IGAA) epitaxial layer structure is completed, it is removed from the MOCVD reaction chamber and moved to a pulsed laser processing station. Then, a pulsed laser is used to scan and irradiate the entire surface of the germanium-based IGAA epitaxial layer structure in an inert gas atmosphere, causing the extremely thin layer on the surface of the InGaAs cell to melt and recrystallize instantaneously, thus repairing defects. Specifically, in this process, nitrogen is used as the inert gas, and the pulsed laser emitted is a KrF excimer laser with a wavelength of 248 nm, a pulse width of 25 ns, and an energy density of 0.5 J / cm². 2 The entire surface of the epitaxial structure is scanned at a scanning speed of 5 mm / s.
[0057] Specifically, this embodiment also includes a defect control system for germanium-based indium gallium arsenide epitaxial layer structures, used to implement the above-mentioned defect control method for germanium-based indium gallium arsenide epitaxial layer structures, including:
[0058] MOCVD reaction chamber;
[0059] The wafer curvature monitoring system integrated into the MOCVD reaction chamber is used to acquire stress evolution data of germanium-based indium gallium arsenide epitaxial layer structure in real time;
[0060] The process controller is used to receive stress evolution data of the germanium-based indium gallium arsenide epitaxial layer structure and compare it with a preset ideal stress-time curve. When the deviation exceeds a set threshold, a control signal is output.
[0061] The actuator automatically adjusts the growth parameters according to the control signal;
[0062] Pulsed laser processing station, providing an inert gas atmosphere and pulsed laser;
[0063] A pulsed laser is used to scan and irradiate the entire surface of a germanium-based indium gallium arsenide epitaxial layer structure in an inert gas atmosphere, causing the extremely thin layer on the surface of the InGaAs cell to melt and recrystallize instantly to repair defects.
[0064] Specifically, this embodiment also includes a germanium-based indium gallium arsenide epitaxial layer structure, which is prepared using the above-mentioned defect control method for germanium-based indium gallium arsenide epitaxial layer structures. It includes a Ge cell, an InGaP nucleation layer, an InGaAs buffer layer, an n-GaAs / p-GaAlAs bottom tunnel junction, a composite buffer layer, an InGaAlAs cell back field, an InGaAs cell, an InGaP window layer, and an n-InGaAs highly doped cap layer, wherein the composite buffer layer includes a composition gradient layer and a dislocation filtering layer.
[0065] Specifically, such as Figure 1 As shown, the highly doped cap layer of n-InGaAs is n-In 0.11 Ga 0.89 As a highly doped cap layer; the p-InGaAs base region and n-InGaAs emitter region in the InGaAs cell are respectively p-InGaAs base region and n-InGaAs emitter region. 0.11 Ga 0.89 As base region and n-In 0.11 Ga 0.89 As emitter region; the back field of the battery in InGaAlAs is In 0.11 Ga 0.89 Al k The back surface of the battery is in As; the graded layer is In. x Ga 1-x Al k An As composition-gradient layer with a thickness of 1.0–3.0 μm, wherein x increases incrementally from 0.01 to 0.15, and its lattice constant is ultimately similar to that of In. 0.11 Ga 0.89 Al k The lattice constant of the back field of the battery in As matches; k takes values from 0.15 to 0.4; the dislocation filter layer is located above the composition-gradient layer and is a strained superlattice structure composed of multiple pairs of In. y Ga 1-y As / In z Ga 1-z As is composed of alternating layers, with y ranging from 0.09 to 0.12 and z ranging from 0.0 to 0.08. The values of y and z result in one layer being under compressive strain and the other under tensile strain.
[0066] Specifically, this embodiment also includes a solar cell comprising the aforementioned germanium-based indium gallium arsenide epitaxial layer structure.
[0067] To demonstrate the superiority of the present invention, Embodiment 1 of the present invention is compared with Comparative Example 1 as follows:
[0068] Compared to Example 1, Comparative Example 1 uses a conventional single buffer layer:
[0069] On a Ge-type solar cell, an InGaP nucleation layer and an InGaAs buffer layer were grown, followed by direct growth of a 2.5 μm thick linearly graded In layer. x Ga 1-x Al k As a buffer layer (x from 0.01 to 0.1), then InGaAs cells and tunnel junctions are grown in exactly the same manner as in Example 1.
[0070] Step S1 uses fixed process parameters for growth without in-situ feedback control; Step S2 uses conventional rapid thermal annealing (RTA), annealing at 750°C in a nitrogen atmosphere for 30 seconds.
[0071] Next, X-ray diffraction tests were performed on the samples of Example 1 and Comparative Example 1, and the results were as follows: Figure 2 The results shown in the figure indicate that the half-width at half-maximum (FWHM) of the InGaAs (004) plane diffraction peak in Example 1 is about 40% narrower than that in Example 1, and the peak intensity of Example 1 is stronger, indicating that its crystal structure quality is significantly better.
[0072] Electrical performance: A simple Ge / InGaAs double-junction cell was fabricated and JV tests were performed. The results are shown in Table 1 below:
[0073] project Jsc (mA / cm2) Voc(mV) FF (%) Eff (%) Example 1 32.97 1127.97 80.1 22.02 Comparative Example 1 25.83 1091.33 74.6 15.55
[0074] Table 1
[0075] Note: This efficiency refers to the efficiency of the dual-junction cell itself, used for comparison.
[0076] Calculations based on surface fitting show that the dislocation density in Comparative Example 1 is ~2 × 10⁷ cm⁻¹. -2 The dislocation density in Example 1 is as low as ~8×10⁴ cm⁻¹. -2 This represents an improvement of nearly three orders of magnitude.
[0077] Device performance: The two materials were fabricated into solar cells. JV data showed that the FF of Comparative Example 1 was 74.6% and the Voc was 1091.33 mV; while the FF of Example 1 was increased to 80.1% and the Voc was increased to 1127.97 mV, showing a significant performance improvement.
[0078] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, any changes made in accordance with the shape and principle of the present invention should be covered within the protection scope of the present invention.
Claims
1. A method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure, characterized in that, This includes regulation of growth structure and regulation of growth processes; in, Growth structure regulation includes: Using a Ge cell as a substrate, an InGaP nucleation layer, an InGaAs buffer layer, an n-GaAs / p-GaAlAs bottom tunnel junction, a composite buffer layer, an InGaAlAs cell back field, an InGaAs cell, an InGaP window layer, and an n-InGaAs highly doped cap layer are sequentially grown on the Ge cell. The composite buffer layer includes a composition gradient layer and a dislocation filtering layer. Growth process regulation includes: A wafer curvature monitoring system integrated into the MOCVD reaction chamber was used to acquire stress evolution data in real time during the growth of germanium-based indium gallium arsenide epitaxial layer structures. During the growth of the composite buffer layer, the wafer curvature monitoring system feeds back the curvature data in the stress evolution data to the process controller in real time. The process controller compares the real-time curvature data with the preset ideal stress-time curve. When the real-time stress deviates from the preset ideal stress-time curve and exceeds the set threshold, the growth parameters are automatically adjusted so that the actual stress state of the germanium-based indium gallium arsenide epitaxial layer structure returns to the preset ideal stress-time curve. After the epitaxial growth of the germanium-based indium gallium arsenide epitaxial layer structure is completed, it is taken out of the MOCVD reaction chamber. Then, a pulsed laser is used to scan and irradiate the entire surface of the germanium-based indium gallium arsenide epitaxial layer structure in an inert gas atmosphere, so that the extremely thin layer on the surface of the InGaAs cell is instantly melted and recrystallized to repair defects.
2. The method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure according to claim 1, characterized in that, The composition-gradient layer is located above the tunnel junction in the n-GaAs / p-GaAlAs substrate, and is In x Ga 1-x Al k As composition graded layer, where x increases in steps from 0.01 to 0.15, eventually matching the lattice constant of the back field of the cell in InGaAlAs; k takes values from 0.15 to 0.4; The dislocation filtering layer is located above the composition-gradient layer and is a strained superlattice structure consisting of multiple pairs of dislocations. In y Ga 1-y As / In z Ga 1-z As is formed by alternating layers, y takes values of 0.09-0.12, and z takes values of 0.0-0.
08.
3. The method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure according to claim 1, characterized in that, The thickness of the component gradient layer is 1.0-3.0 μm.
4. The method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure according to claim 2, characterized in that, The strained superlattice structure of the dislocation filter layer is In 0.1 Ga 0.9 As / GaAs superlattice pairs, or In 0.12 Ga 0.88 As / In 0.08 Ga 0.92 As superlattice pairs.
5. The method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure according to claim 1, characterized in that, The growth parameters include trimethylindium flow rate, system V / III ratio, growth temperature, and growth rate.
6. The method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure according to claim 1, characterized in that, The InGaAs cell includes a p-InGaAs base region and an n-InGaAs emitter region, and the total thickness of the p-InGaAs base region, the n-InGaAs emitter region, and the back field of the InGaAlAs cell is 1800~2500nm.
7. The method for controlling defects in a germanium-based indium gallium arsenide epitaxial layer structure according to claim 1, characterized in that, The pulsed laser emitted by the pulsed laser is a KrF excimer laser with a wavelength of 248 nm, a pulse width of 10–50 ns, and an energy density of 0.3–0.8 J / cm². 2 .
8. A defect control system for germanium-based indium gallium arsenide epitaxial layer structures, used to implement the defect control method for germanium-based indium gallium arsenide epitaxial layer structures according to any one of claims 1-7, comprising: MOCVD reaction chamber; The wafer curvature monitoring system integrated into the MOCVD reaction chamber is used to acquire stress evolution data of germanium-based indium gallium arsenide epitaxial layer structure in real time; The process controller is used to receive stress evolution data of the germanium-based indium gallium arsenide epitaxial layer structure and compare it with a preset ideal stress-time curve. When the deviation exceeds a set threshold, a control signal is output. The actuator automatically adjusts the growth parameters according to the control signal; Pulsed laser processing station, providing an inert gas atmosphere and pulsed laser; A pulsed laser is used to scan and irradiate the entire surface of a germanium-based indium gallium arsenide epitaxial layer structure in an inert gas atmosphere, causing the extremely thin layer on the surface of the InGaAs cell to melt and recrystallize instantly to repair defects.
9. A germanium-based indium gallium arsenide epitaxial layer structure, prepared using the defect control method for germanium-based indium gallium arsenide epitaxial layer structures according to any one of claims 1-7, characterized in that, It includes a Ge cell, an InGaP nucleation layer, an InGaAs buffer layer, an n-GaAs / p-GaAlAs bottom tunnel junction, a composite buffer layer, an InGaAlAs cell back field, an InGaAs cell, an InGaP window layer, and an n-InGaAs highly doped cap layer, arranged sequentially from bottom to top on the Ge cell; the composite buffer layer includes a composition gradient layer and a dislocation filtering layer.
10. A solar cell, characterized in that, Includes the germanium-based indium gallium arsenide epitaxial layer structure as described in claim 9.