Method for producing gallium arsenide epitaxial layer and structure

Abstract

The application provides a preparation method and structure of a gallium arsenide epitaxial layer. The method comprises the following steps: under the protection of an As beam, setting the temperature of a GaAs substrate as a first preset temperature, opening a Ga beam, and growing a GaAs buffer layer on the GaAs substrate; opening a P-type doping source beam, and growing a P-type body-doped GaAs epitaxial layer on the GaAs buffer layer; turning off the Ga beam, and growing a P-type planar doping layer on the P-type body-doped GaAs epitaxial layer; repeating the steps of "opening the Ga beam, and growing a new P-type body-doped GaAs epitaxial layer on the current P-type planar doping layer" and "turning off the Ga beam, and growing a new P-type planar doping layer on the current P-type body-doped GaAs epitaxial layer" until the number of layers of the P-type body-doped GaAs epitaxial layer reaches a preset number of layers, then turning off the Ga beam and the P-type doping source beam, and obtaining a gallium arsenide epitaxial layer structure. The application can improve the P-type doping concentration of gallium arsenide.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a preparation method and structure of a gallium arsenide epitaxial layer. Background Art

[0002] With the rapid development of solar cells, gallium arsenide (GaAs) and its related III-V compound multi-junction tandem cells have attracted extensive research. Multi-junction tandem solar cells rely on each sub-cell absorbing the solar spectrum that matches its bandgap, effectively improving photoelectric conversion efficiency. To overcome the reverse potential barrier between adjacent sub-cells, GaAs-based tunnel junctions are typically added between the sub-cells to facilitate current flow.

[0003] In the design of GaAs-based tunnel junction, the P-type doping concentration is 10 19 ~10 20 By increasing the P-type doping concentration, the tunnel peak current can be increased and the performance of the tunnel junction can be improved. In practical applications, the P-type doping concentration of GaAs is usually increased by growing an epitaxial layer on a GaAs substrate. However, due to the hardware limitations of the doping equipment, the existing P-type doping concentration of GaAs can only reach 10 19 The doping concentration cannot be further increased. Summary of the Invention

[0004] The embodiments of the present invention provide a method and structure for preparing a gallium arsenide epitaxial layer to solve the problem in the prior art that the P-type doping concentration of gallium arsenide cannot be further increased.

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing a gallium arsenide epitaxial layer, comprising:

[0006] Under the protection of the As beam, the temperature of the GaAs substrate is set to a first preset temperature, and the Ga beam is turned on to grow a GaAs buffer layer on the GaAs substrate;

[0007] Turning on a P-type doping source beam to grow a P-type bulk-doped GaAs epitaxial layer on the GaAs buffer layer;

[0008] Turning off the Ga beam, and growing a P-type planar doped layer on the P-type bulk-doped GaAs epitaxial layer;

[0009] Repeat the steps of “turning on the Ga beam to grow a new P-type bulk-doped GaAs epitaxial layer on the current P-type planar doped layer” and “turning off the Ga beam to grow a new P-type planar doped layer on the current P-type bulk-doped GaAs epitaxial layer” until the number of P-type bulk-doped GaAs epitaxial layers reaches a preset number of layers, turning off the Ga beam and the P-type doping source beam to obtain a gallium arsenide epitaxial layer structure; the top layer of the gallium arsenide epitaxial layer structure is a P-type bulk-doped GaAs epitaxial layer.

[0010] In a possible implementation, under the protection of the As beam, the temperature of the GaAs substrate is set to a first preset temperature, and the Ga beam is turned on, and before the GaAs buffer layer is grown on the GaAs substrate, the method further includes:

[0011] Cleaning the GaAs substrate and removing water vapor and surface adsorbed molecules in the GaAs substrate by heating;

[0012] Under the protection of the As beam, the GaAs substrate is further heated to a second preset temperature to remove the oxide layer on the surface of the GaAs substrate.

[0013] In a possible implementation, the first preset temperature is any temperature value between 650° C. and 700° C.;

[0014] The second preset temperature is any temperature value between 700° C. and 750° C.

[0015] In a possible implementation, the P-type doping source beam includes: a C beam or a Be beam;

[0016] The P-type body-doped GaAs epitaxial layer includes: a C-body-doped GaAs epitaxial layer or a Be-body-doped GaAs epitaxial layer;

[0017] The P-type planar doping layer includes: a C-type planar doping layer or a Be-type planar doping layer.

[0018] In one possible implementation, the size of the GaAs substrate ranges from 2 inches to 6 inches;

[0019] The thickness of the GaAs buffer layer ranges from 10 to 200 nm.

[0020] In a possible implementation, the thickness of the P-type body-doped GaAs epitaxial layer is in the range of 5 nm to 50 nm;

[0021] The doping concentration of the P-type body-doped GaAs epitaxial layer is in the range of 1E19 cm -3 ~3E19cm -3 .

[0022] In a possible implementation, the step of growing a P-type planar doped layer on the P-type bulk-doped GaAs epitaxial layer includes:

[0023] A P-type planar doped layer is grown on the P-type bulk-doped GaAs epitaxial layer within a preset time; the preset time is less than or equal to 60s.

[0024] In a possible implementation, the growth rates of the GaAs buffer layer and the P-type body-doped GaAs epitaxial layer are both 1000 nm / h.

[0025] In a possible implementation, the preset number of layers ranges from 2 to 21.

[0026] In a second aspect, an embodiment of the present invention provides a gallium arsenide epitaxial layer structure, comprising:

[0027] GaAs substrate;

[0028] A GaAs buffer layer grown on the upper surface of the GaAs substrate;

[0029] A cyclic epitaxial layer grown on the upper surface of the GaAs buffer layer; the cyclic epitaxial layer comprises at least one composite epitaxial layer, each composite epitaxial layer comprising a P-type bulk-doped GaAs epitaxial layer and a P-type planar doped layer grown on the upper surface of the P-type bulk-doped GaAs epitaxial layer;

[0030] A P-type body-doped GaAs epitaxial layer is grown on the upper surface of the cyclic epitaxial layer.

[0031] An embodiment of the present invention provides a method and structure for preparing a gallium arsenide epitaxial layer. The method comprises the following steps: setting the temperature of a GaAs substrate to a first preset temperature under the protection of an As beam, turning on the Ga beam, and growing a GaAs buffer layer on the GaAs substrate; turning on a P-type doping source beam, and growing a P-type bulk-doped GaAs epitaxial layer on the GaAs buffer layer; turning off the Ga beam, and growing a P-type planar doped layer on the P-type bulk-doped GaAs epitaxial layer; repeating the steps of "turning on the Ga beam, and growing a new P-type bulk-doped GaAs epitaxial layer on the current P-type planar doped layer" and "turning off the Ga beam, and growing a new P-type planar doped layer on the current P-type bulk-doped GaAs epitaxial layer" until the number of P-type bulk-doped GaAs epitaxial layers reaches a preset number, turning off the Ga beam and the P-type doping source beam, and obtaining a gallium arsenide epitaxial layer structure; wherein the top layer of the gallium arsenide epitaxial layer structure is a P-type bulk-doped GaAs epitaxial layer. By periodically growing P-type bulk-doped GaAs epitaxial layers and P-type planar-doped layers, a P-type planar-doped layer is positioned between every two P-type bulk-doped GaAs epitaxial layers. The P-type dopant source in each P-type planar-doped layer diffuses to the two adjacent P-type bulk-doped GaAs epitaxial layers, thereby increasing the doping concentration in each P-type bulk-doped GaAs epitaxial layer and, in turn, the P-type doping concentration of the GaAs epitaxial layer structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 This is a flow chart of a method for preparing a gallium arsenide epitaxial layer provided by one embodiment of the present invention;

[0034] Figure 2 is a flow chart of a method for preparing a gallium arsenide epitaxial layer provided by another embodiment of the present invention;

[0035] Figure 3 It is a structural schematic diagram of a gallium arsenide epitaxial layer structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] To help those skilled in the art better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of this solution, not all of it. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this solution.

[0037] Throughout the specification, claims, and accompanying figures of this solution, the term "including" and any variations thereof mean "including, but not limited to," and are intended to cover non-exclusive inclusions and are not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish between different objects, not to describe a specific order.

[0038] In the prior art, there are many processes for achieving epitaxial growth, including molecular beam epitaxy (MBE), chemical vapor deposition (CVD), atmospheric pressure epitaxy, and reduced pressure epitaxy.

[0039] The MBE process is a semiconductor thin film epitaxial growth process that achieves atomic-level precision control under ultra-high vacuum. Compared to other epitaxial growth processes, the MBE process operates in a non-equilibrium state, resulting in lower material growth temperatures, less atomic diffusion, and a steep PN junction interface, meeting the steep interface requirements of GaAs-based tunnel junctions.

[0040] Therefore, the embodiment of the present invention uses the molecular beam epitaxy process to prepare the GaAs epitaxial layer. It is understandable that the embodiment of the present invention is not limited to a specific epitaxial growth process, and users can also choose other epitaxial growth processes to prepare the GaAs epitaxial layer as needed.

[0041] In the prior art, when using the MBE process to prepare GaAs epitaxial layers, a GaAs buffer layer and a P-type bulk-doped GaAs epitaxial layer are usually grown sequentially on the surface of the GaAs substrate to achieve the purpose of doping the GaAs with a P-type dopant source. However, due to the limitations of the furnace temperature and current of the P-type dopant source furnace, the doping concentration is usually 1E19cm -3 The present invention provides a method for preparing a GaAs epitaxial layer to further increase the GaAs P-type doping concentration. Figure 1 The following is a flow chart of the method for preparing a gallium arsenide epitaxial layer provided in an embodiment of the present invention. Figure 1 As shown, the method for preparing a gallium arsenide epitaxial layer includes:

[0042] Step 101 : Under the protection of the As beam, the temperature of the GaAs substrate is set to a first preset temperature, and the Ga beam is turned on to grow a GaAs buffer layer on the GaAs substrate.

[0043] The GaAs substrate is placed in the growth chamber of the molecular beam epitaxy equipment. Under the protection of the As beam, the temperature of the GaAs substrate is set to a first preset temperature. The Ga source furnace beam shutter is opened to provide a Ga beam to epitaxially grow a GaAs buffer layer on the GaAs substrate.

[0044] Optionally, the size of the GaAs substrate ranges from 2 inches to 6 inches.

[0045] Optionally, the first preset temperature is any temperature value between 650°C and 700°C.

[0046] Optionally, the thickness of the GaAs buffer layer ranges from 10 to 200 nm.

[0047] Optional, see Figure 2 Before step 101, the following steps may also be included:

[0048] Step 105 , cleaning the GaAs substrate and removing water vapor and surface adsorbed molecules in the GaAs substrate by heating.

[0049] Cleaning the GaAs substrate effectively removes surface impurities. The cleaned GaAs substrate is then loaded into the molecular beam epitaxy (MBE) equipment's loading and unloading chamber, which is then evacuated to create a vacuum environment. Heating the GaAs substrate effectively removes moisture.

[0050] After removing the water vapor, the GaAs substrate is placed in a pretreatment chamber and further heated to remove surface adsorbed molecules on the GaAs substrate. The surface adsorbed molecules here can be gas molecules, such as CO2 or N2.

[0051] In practical applications, when heated to about 100°C, water vapor in the GaAs substrate can be effectively removed. When heated to about 400°C, surface adsorbed molecules such as CO2 can be effectively removed.

[0052] Step 106 : Under the protection of the As beam, the GaAs substrate is further heated to a second preset temperature to remove the oxide layer on the surface of the GaAs substrate.

[0053] After the surface adsorbed molecules on the GaAs substrate are completely removed, the substrate is placed in a growth chamber and, under the protection of the As beam, the GaAs substrate is further heated to a second preset temperature to remove the oxide layer on the surface of the GaAs substrate.

[0054] Optionally, the second preset temperature is any temperature value between 700°C and 750°C.

[0055] Step 102 , turning on the P-type doping source beam to grow a P-type bulk-doped GaAs epitaxial layer on the GaAs buffer layer.

[0056] After the Ga beam is already on, the P-type dopant source beam is turned on. By providing the Ga beam and the P-type dopant source beam simultaneously, a P-type bulk-doped GaAs epitaxial layer is grown on the GaAs buffer layer. It can be understood that the P-type bulk-doped GaAs epitaxial layer means that the GaAs is doped with the P-type dopant source.

[0057] Optionally, the P-type doping source beam may include a C beam or a Be beam. Correspondingly, the P-type bulk-doped GaAs epitaxial layer may include a C-bulk-doped GaAs epitaxial layer or a Be-bulk-doped GaAs epitaxial layer.

[0058] The P-type doping source may include C or Be. Since the diffusion coefficient of C is one order of magnitude smaller than that of Be and its solubility is also greater than that of Be, in practical applications, choosing C as the P-type doping source is a better choice.

[0059] Optionally, the thickness of the P-type body-doped GaAs epitaxial layer ranges from 5 nm to 50 nm.

[0060] Optionally, the doping concentration of the P-type bulk doped GaAs epitaxial layer is in the range of 1E19 cm -3 ~3E19cm -3 .

[0061] Optionally, the growth rates of the GaAs buffer layer and the P-type body-doped GaAs epitaxial layer are both 1000 nm / h.

[0062] Step 103 , turning off the Ga beam, and growing a P-type planar doped layer on the P-type bulk doped GaAs epitaxial layer.

[0063] Optionally, the P-type planar doping layer includes: a C-type planar doping layer or a Be-type planar doping layer.

[0064] Close the Ga source furnace beam shutter, turning off the Ga beam while maintaining the P-type dopant source beam on to continue growing the P-type planar doped layer on the P-type bulk-doped GaAs epitaxial layer. Since the Ga beam is now off, the P-type planar doped layer contains only the P-type dopant source. The P-type planar doped layer can be simply understood as a layer of C atoms or a layer of Be atoms.

[0065] Optionally, step 103 may include:

[0066] A P-type planar doped layer is grown on the P-type bulk doped GaAs epitaxial layer within a preset time, wherein the preset time is less than or equal to 60 seconds.

[0067] Step 104 repeats the steps of "turning on the Ga beam to grow a new P-type bulk-doped GaAs epitaxial layer on the current P-type planar doped layer" and "turning off the Ga beam to grow a new P-type planar doped layer on the current P-type bulk-doped GaAs epitaxial layer" until the number of P-type bulk-doped GaAs epitaxial layers reaches a predetermined number. Then, the Ga beam and the P-type doping source beam are turned off to obtain a GaAs epitaxial layer structure. The top layer of the GaAs epitaxial layer structure is a P-type bulk-doped GaAs epitaxial layer.

[0068] Optionally, the preset number of layers ranges from 2 to 21.

[0069] Repeat the steps of "turning on the Ga beam to grow a new P-type bulk-doped GaAs epitaxial layer on the current P-type planar doped layer" and "turning off the Ga beam to grow a new P-type planar doped layer on the current P-type bulk-doped GaAs epitaxial layer", that is, periodically growing the P-type bulk-doped GaAs epitaxial layer and the P-type planar doped layer until the number of layers of the P-type bulk-doped GaAs epitaxial layer reaches a preset number of layers, turning off the Ga beam and the P-type doping source beam, cooling under the protection of the As beam, and obtaining a gallium arsenide epitaxial layer structure.

[0070] A P-type planar doped layer is placed between every two P-type bulk-doped GaAs epitaxial layers. The P-type dopant source in each P-type planar doped layer diffuses to the two adjacent P-type bulk-doped GaAs epitaxial layers, thereby increasing the doping concentration of each P-type bulk-doped GaAs epitaxial layer and, in turn, the P-type doping concentration of the GaAs epitaxial layer structure.

[0071] For example, the embodiment of the present invention further provides a specific example to demonstrate the feasibility of the method for preparing the gallium arsenide epitaxial layer in increasing the P-type doping concentration:

[0072] Step 1: After cleaning the GaAs substrate, place it in the molecular beam epitaxy equipment loading and unloading chamber, and use the vacuum pump group to evacuate the loading and unloading chamber; after heating the chamber to remove moisture, the GaAs substrate is sent to the pretreatment chamber, heated again to remove the surface adsorbed molecules on the GaAs substrate, and then sent to the growth chamber to prepare for growing the epitaxial layer.

[0073] Step 2: Under the protection of the As beam, the GaAs substrate is heated to 750°C, at which temperature the oxide layer on the surface of the GaAs substrate is removed;

[0074] Step 3: Cool the GaAs substrate to 680°C, open the Ga source furnace beam shutter, and epitaxially grow a GaAs buffer layer on the GaAs substrate; the thickness of the GaAs buffer layer is 50 nm;

[0075] Step 4: Open the C source furnace beam shutter and grow a C-body doped GaAs epitaxial layer on the GaAs buffer layer; the thickness of the C-body doped GaAs epitaxial layer is 5 nm;

[0076] Step 5: Close the Ga source furnace beam shutter and keep the C source furnace beam shutter open for 36 seconds to grow a C plane doped layer on the C body doped GaAs epitaxial layer;

[0077] Step 6: Repeat the steps of growing a C-bulk doped GaAs epitaxial layer and growing a C-plane doped layer for a total of 10 cycles;

[0078] Step 7: Open the Ga source furnace beam shutter and grow a C-body doped GaAs epitaxial layer on the C-plane doped layer. After the growth is completed, close the Ga and C source furnace beam shutters, cool down under the protection of the As beam, and obtain a GaAs epitaxial layer structure.

[0079] In this example, C is selected as the P-type doping source. The size of the GaAs substrate is 4 inches. The growth rates of the GaAs buffer layer and the C-body doped GaAs epitaxial layer are both 1000 nm / h. The doping concentration of the C-body doped GaAs epitaxial layer is 1.0E19 cm -3 Finally, the GaAs epitaxial layer structure was tested and the C doping concentration of the GaAs epitaxial layer structure was found to be 3.025E19cm -3 , the doping concentration is increased to 3 times of the original. It can be seen that the GaAs epitaxial layer structure obtained by this preparation method can effectively increase the P-type doping concentration of GaAs.

[0080] An embodiment of the present invention provides a method for preparing a gallium arsenide epitaxial layer, comprising: under the protection of an As beam, setting the temperature of a GaAs substrate to a first preset temperature, turning on the Ga beam, and growing a GaAs buffer layer on the GaAs substrate; turning on a P-type doping source beam, and growing a P-type body-doped GaAs epitaxial layer on the GaAs buffer layer; turning off the Ga beam, and growing a P-type planar doped layer on the P-type body-doped GaAs epitaxial layer; repeatedly performing the steps of "turning on the Ga beam, and growing a new P-type body-doped GaAs epitaxial layer on the current P-type planar doped layer" and "turning off the Ga beam, and growing a new P-type planar doped layer on the current P-type body-doped GaAs epitaxial layer" until the number of P-type body-doped GaAs epitaxial layers reaches a preset number, turning off the Ga beam and the P-type doping source beam, and obtaining a gallium arsenide epitaxial layer structure; and periodically growing the P-type body-doped GaAs epitaxial layer and the P-type planar doped layer so that a P-type planar doped layer is arranged between every two P-type body-doped GaAs epitaxial layers. The P-type doping source in each P-type planar doped layer is diffused to the two adjacent P-type bulk-doped GaAs epitaxial layers, thereby increasing the doping concentration on each P-type bulk-doped GaAs epitaxial layer and further increasing the P-type doping concentration of the GaAs epitaxial layer structure;

[0081] In addition, the present application adopts molecular beam epitaxial growth technology, and its growth temperature is relatively low, which makes the diffusion of the P-type doping source smaller and is more conducive to increasing the P-type doping concentration; at the same time, the molecular beam epitaxial growth technology has strong process versatility and is suitable for all high-concentration material structures that require P-type doping.

[0082] See also Figure 3 , an embodiment of the present invention further provides a gallium arsenide epitaxial layer structure, comprising:

[0083] GaAs substrate 31;

[0084] A GaAs buffer layer 32 grown on the upper surface of a GaAs substrate 31;

[0085] A cyclic epitaxial layer 33 grown on the upper surface of the GaAs buffer layer 32; the cyclic epitaxial layer 33 includes at least one composite epitaxial layer 331, each composite epitaxial layer 331 including a P-type bulk-doped GaAs epitaxial layer 3311 and a P-type planar doped layer 3312 grown on the upper surface of the P-type bulk-doped GaAs epitaxial layer 3311;

[0086] A P-type body-doped GaAs epitaxial layer 34 is grown on the upper surface of the cyclic epitaxial layer 33 .

[0087] It is understandable that Figure 3 This is only an exemplary drawing and does not specifically limit the number of composite epitaxial layers in the gallium arsenide epitaxial layer structure.

[0088] Optionally, the P-type bulk-doped GaAs epitaxial layer includes a C-bulk-doped GaAs epitaxial layer or a Be-bulk-doped GaAs epitaxial layer. Correspondingly, the P-type planar doped layer includes a C-bulk-doped layer or a Be-bulk-doped layer.

[0089] Optionally, the size of the GaAs substrate ranges from 2 inches to 6 inches.

[0090] Optionally, the thickness of the GaAs buffer layer ranges from 10 to 200 nm.

[0091] Optionally, the thickness of the P-type body-doped GaAs epitaxial layer ranges from 5 nm to 50 nm.

[0092] Optionally, the doping concentration of the P-type bulk doped GaAs epitaxial layer is in the range of 1E19 cm -3 ~3E19cm -3 .

[0093] Optionally, the number of the composite epitaxial layers may be any value between 1 and 20.

[0094] An embodiment of the present invention provides a gallium arsenide epitaxial layer structure, comprising: a GaAs substrate 31; a GaAs buffer layer 32 grown on the upper surface of the GaAs substrate 31; a cyclic epitaxial layer 33 grown on the upper surface of the GaAs buffer layer 32; the cyclic epitaxial layer 33 comprising at least one composite epitaxial layer 331, each composite epitaxial layer 331 comprising a P-type bulk-doped GaAs epitaxial layer 3311 and a P-type planar-doped layer 3312 grown on the upper surface of the P-type bulk-doped GaAs epitaxial layer 3311; and a P-type bulk-doped GaAs epitaxial layer 34 grown on the upper surface of the cyclic epitaxial layer 33. The P-type bulk-doped GaAs epitaxial layers are grown on the cyclic epitaxial layers, such that a P-type planar-doped layer is disposed between every two P-type bulk-doped GaAs epitaxial layers. The P-type doping source in each P-type planar doped layer is diffused to the two adjacent P-type bulk-doped GaAs epitaxial layers, thereby increasing the doping concentration on each P-type bulk-doped GaAs epitaxial layer and further increasing the P-type doping concentration of the GaAs epitaxial layer structure.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a gallium arsenide epitaxial layer, characterized in that: include: Under the protection of the As beam, the temperature of the GaAs substrate is set to a first preset temperature, and the Ga beam is turned on to grow a GaAs buffer layer on the GaAs substrate; Turning on a P-type doping source beam to grow a P-type bulk-doped GaAs epitaxial layer on the GaAs buffer layer; Turning off the Ga beam, and growing a P-type planar doped layer on the P-type bulk-doped GaAs epitaxial layer; Repeating the steps of "turning on the Ga beam to grow a new P-type bulk-doped GaAs epitaxial layer on the current P-type planar doped layer" and "turning off the Ga beam to grow a new P-type planar doped layer on the current P-type bulk-doped GaAs epitaxial layer" until the number of P-type bulk-doped GaAs epitaxial layers reaches a preset number of layers, turning off the Ga beam and the P-type doping source beam to obtain a gallium arsenide epitaxial layer structure; the top layer of the gallium arsenide epitaxial layer structure is a P-type bulk-doped GaAs epitaxial layer; the preset number of layers ranges from 2 to 21.

2. The method for preparing a gallium arsenide epitaxial layer according to claim 1, characterized in that: Under the protection of the As beam, the temperature of the GaAs substrate is set to a first preset temperature, and the Ga beam is turned on. Before growing a GaAs buffer layer on the GaAs substrate, the method further includes: Cleaning the GaAs substrate and removing water vapor and surface adsorbed molecules in the GaAs substrate by heating; Under the protection of the As beam, the GaAs substrate is further heated to a second preset temperature to remove the oxide layer on the surface of the GaAs substrate.

3. The method for preparing a gallium arsenide epitaxial layer according to claim 2, characterized in that: The first preset temperature is any temperature value between 650°C and 700°C; The second preset temperature is any temperature value between 700° C. and 750° C.

4. The method for preparing a gallium arsenide epitaxial layer according to claim 1 or 2, characterized in that: The P-type doping source beam includes: a C beam or a Be beam; The P-type body-doped GaAs epitaxial layer includes: a C-body-doped GaAs epitaxial layer or a Be-body-doped GaAs epitaxial layer; The P-type planar doping layer includes: a C-type planar doping layer or a Be-type planar doping layer.

5. The method for preparing a gallium arsenide epitaxial layer according to claim 1 or 2, characterized in that: The size of the GaAs substrate ranges from 2 inches to 6 inches; The thickness of the GaAs buffer layer ranges from 10 to 200 nm.

6. The method for preparing a gallium arsenide epitaxial layer according to claim 1 or 2, characterized in that: The thickness of the P-type body-doped GaAs epitaxial layer is in the range of 5 nm to 50 nm; The doping concentration of the P-type body-doped GaAs epitaxial layer is in the range of 1E19 cm -3 ~3E19cm -3 .

7. The method for preparing a gallium arsenide epitaxial layer according to claim 1 or 2, characterized in that: The step of growing a P-type planar doped layer on the P-type bulk-doped GaAs epitaxial layer comprises: A P-type planar doped layer is grown on the P-type bulk-doped GaAs epitaxial layer within a preset time; the preset time is less than or equal to 60s.

8. The method for preparing a gallium arsenide epitaxial layer according to claim 1 or 2, characterized in that: The growth rates of the GaAs buffer layer and the P-type body-doped GaAs epitaxial layer are both 1000 nm / h.

9. A gallium arsenide epitaxial layer structure, characterized in that: include: GaAs substrate; A GaAs buffer layer grown on the upper surface of the GaAs substrate; A cyclic epitaxial layer grown on the upper surface of the GaAs buffer layer; the cyclic epitaxial layer comprises at least one composite epitaxial layer, each composite epitaxial layer comprising a P-type bulk-doped GaAs epitaxial layer and a P-type planar doped layer grown on the upper surface of the P-type bulk-doped GaAs epitaxial layer; A P-type body-doped GaAs epitaxial layer is grown on the upper surface of the cyclic epitaxial layer; the number of layers of the P-type body-doped GaAs epitaxial layer ranges from 2 to 21.

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