A gallium nitride semiconductor epitaxy and its preparation method and power and radio frequency device

Abstract

The present invention relates to a gallium nitride semiconductor epitaxy and a preparation method thereof, as well as power and radio frequency devices. The gallium nitride semiconductor epitaxy comprises a stacked substrate, a buffer layer and a stress adjustment layer; the buffer layer comprises a semiconductor material; the semiconductor material comprises AlN and / or AlInN. The present invention slows down the screw and edge dislocations generated between the substrate and the stress adjustment layer due to lattice mismatch and thermal mismatch, and reduces the dissolution of gallium, thereby improving the quality of the epitaxial crystal.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and relates to a gallium nitride semiconductor epitaxy, and in particular to a gallium nitride semiconductor epitaxy and a preparation method thereof, a power device, and a radio frequency device. Background Art

[0002] Gallium nitride is considered to be the most important semiconductor material after silicon. Gallium nitride is a wide bandgap semiconductor material. Its spectrum covers the entire visible light region. It can be made into blue and white light-emitting diodes for display, TV backlight and general lighting; it can be made into green / blue light-emitting diodes, together with AlGaInP-based red light-emitting diodes, for full-color display; it can also be made into ultraviolet lasers for data storage. In addition to its excellent optical properties, gallium nitride also has excellent electrical properties: it has characteristics such as large bandgap width, high critical breakdown electric field, high thermal conductivity and high electron drift saturation velocity, and has high spontaneous and piezoelectric polarization effects. It can produce high mobility and high surface density two-dimensional electron gas in the production of epitaxial heterostructures. Based on the above characteristics, the device can have high current density, low on-resistance, high operating frequency, high thermal stability and small size. Therefore, gallium nitride can be used in microwave devices, high-power switching devices, etc. Among them, the voltage tolerance of gallium nitride semiconductor materials is the main indicator of its performance.

[0003] In the prior art, the doping process of the planar process of general semiconductor devices forms an impurity diffusion junction with a certain curvature under the surface of the semiconductor material. The voltage-bearing capacity of this junction is often much lower than that of an ideal parallel plane junction without curvature, which will affect the final operating voltage of the semiconductor device. Therefore, many methods have emerged to improve the breakdown voltage of the curvature junction produced by the planar process, which are generally referred to as junction termination technology.

[0004] CN 108428741A discloses a gallium nitride semiconductor device and a method for manufacturing the same, the method comprising: growing an indium-containing buffer layer on a first surface of a substrate, the buffer layer comprising an indium-containing Al x Ga 1-x N layers, wherein 0≤x≤1; forming a first gallium nitride layer that is not intentionally doped on the surface of the buffer layer away from the substrate; forming a second gallium nitride layer doped with carbon on the surface of the first gallium nitride layer away from the buffer layer; forming a third gallium nitride layer that is not intentionally doped on the side of the second gallium nitride layer away from the first gallium nitride layer; forming an Al y GaN 1-y N layers, wherein 0<y≤1. The gallium nitride semiconductor device manufactured by the method can improve the breakdown voltage of the gallium nitride semiconductor device, reduce the probability of cracks occurring in the gallium nitride semiconductor device during epitaxial growth and chip manufacturing, and improve the performance of the gallium nitride semiconductor device.

[0005] CN 101330097 discloses a semiconductor structure and manufacturing method for increasing breakdown voltage. The semiconductor structure includes five parts, namely, semiconductor material, main diffusion junction, voltage-resistant layer, depletion termination region and dielectric layer. The main diffusion junction, voltage-resistant layer and depletion termination region are all in the semiconductor material, the conductivity type of the main diffusion junction and the voltage-resistant layer is opposite to that of the semiconductor material, and the conductivity type of the depletion termination region is the same as that of the semiconductor material. This structure can increase the breakdown voltage of the main diffusion junction by more than 25%, and can make the breakdown voltage of the main diffusion junction reach more than 75% of the maximum avalanche breakdown voltage of the ideal parallel plane junction of the semiconductor material. The invention can be applied to the junction terminal of semiconductor devices with a voltage range from tens of volts to thousands of volts, and is particularly suitable for the structure and manufacture of high-voltage semiconductor devices and integrated circuits with shallow junction and low-temperature processes.

[0006] Although the above technical solutions improve the semiconductor structure and increase the withstand voltage, there are problems with the quality of the epitaxial crystal caused by the lattice constant mismatch rate and the difference in thermal expansion coefficient between the substrate and the outer layer, which affects the performance of the semiconductor device.

[0007] Therefore, how to improve the quality of epitaxial crystals caused by the lattice constant mismatch rate and thermal expansion coefficient difference between the substrate and the outer layer, ensure high voltage withstand capability, and enhance the performance of semiconductor devices is a technical problem that needs to be urgently solved in the field of semiconductor manufacturing technology. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a gallium nitride semiconductor epitaxy and a preparation method thereof, as well as a power and radio frequency device. By providing a buffer layer containing a semiconductor material, wherein the semiconductor material includes AlN and / or AlInN, the crystal quality is improved and the voltage tolerance capability is enhanced.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a gallium nitride semiconductor epitaxy, wherein the gallium nitride semiconductor epitaxy comprises a stacked substrate, a buffer layer, and a stress adjustment layer;

[0011] The buffer layer comprises a semiconductor material;

[0012] The semiconductor material includes AlN and / or AlInN.

[0013] The present invention grows a buffer layer between the substrate and the stress adjustment layer, wherein the buffer layer contains semiconductor material, thereby alleviating the screw and edge dislocations caused by lattice mismatch and thermal mismatch between the substrate and the stress adjustment layer, and reducing the dissolution of gallium, thereby improving the quality of the crystal and showing a higher voltage resistance.

[0014] Preferably, the buffer layer comprises a doped material.

[0015] Preferably, the doping material includes any one or a combination of at least two of the elements carbon, beryllium, magnesium or iron, typical but non-limiting combinations include a combination of carbon and beryllium, a combination of beryllium and magnesium, a combination of magnesium and iron, a combination of carbon and magnesium, a combination of carbon and iron, a combination of beryllium and iron, a combination of carbon, beryllium and magnesium, a combination of beryllium, magnesium and iron, or a combination of carbon, beryllium, magnesium and iron.

[0016] Due to the P-type impurity compensation method and the deep energy level impurity compensation method, the initial background concentration of the film tends to the presence of N vacancies and O impurities at the energy level, both of which contain a certain background concentration. Therefore, the doping material provided by the present invention can obtain a high-resistance layer through the P-type doping compensation method and the introduction of deep energy level defects to form electron traps, so as to facilitate the subsequent growth of a GaN layer with high crystal quality to reduce the leakage path.

[0017] Preferably, the doping concentration of the doping element in the buffer layer is 1.0×E17 to 1.0×E19 atoms / cm 3 , for example, it can be 1.0×E17atoms / cm 3 、5.0×E17atoms / cm 3 、1.0×E18atoms / cm 3 、5.0×E18atoms / cm 3 or 1.0×E19atoms / cm 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0018] When the doping concentration is greater than 1.0×E19atoms / cm 3 When the impurity concentration is too high, it will be detrimental to the quality growth of single crystal thin films, resulting in subsequent film cracking and high background concentration, which will affect the operation of the device.

[0019] Preferably, the substrate comprises any one of Al2O3, GaN, AlN, Si, GaO or SiC, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of Al2O3 and GaN, a combination of GaN and AlN, a combination of AlN and Si, a combination of Si and GaO, a combination of GaO or SiC, a combination of Si and SiC, a combination of Al2O3, GaN and AlN, a combination of GaN, AlN and Si, a combination of AlN, Si and SiC, a combination of Al2O3, GaN, AlN and Si, a combination of Al2O3, GaN, AlN and GaO, a combination of GaN, AlN, Si and GaO, a combination of AlN, Si, GaO and SiC, a combination of GaN, AlN, Si and SiC, or a combination of Al2O3, GaN, AlN, Si and SiC.

[0020] Preferably, the stress adjustment layer includes any one of AlN, GaN, AlGaN or AlInGaN or a combination of at least two of them. Typical but non-limiting combinations include a combination of AlN and GaN, a combination of GaN and AlGaN, a combination of AlGaN and AlInGaN, a combination of AlN and AlGaN, a combination of GaN and AlInGaN, a combination of AlN, GaN and AlGaN, a combination of GaN, AlGaN and AlInGaN, or a combination of AlN, GaN, AlGaN and AlInGaN.

[0021] Preferably, the thickness of the substrate is greater than 300 μm, for example, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, the thickness of the buffer layer is 1 to 1000 nm, for example, 1 nm, 5 nm, 100 nm, 300 nm, 500 nm or 1000 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 100 to 500 nm.

[0023] Preferably, the thickness of the stress adjustment layer is 1 to 30 μm, for example, 0.5 μm, 2 μm, 4 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm or 30 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] In a second aspect, the present invention provides a method for preparing the gallium nitride semiconductor epitaxy according to the first aspect, the method comprising the following steps:

[0025] (1) growing a buffer layer on the surface of the substrate;

[0026] (2) A stress adjustment layer is grown on the surface of the obtained buffer layer.

[0027] The growth method described in the present invention is a vapor phase epitaxial growth method.

[0028] Preferably, the growth temperature in step (1) is 500-1200°C, for example, it can be 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C or 1200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the growth reaction chamber pressure in step (1) is 20 to 500 torr, for example, 20 torr, 50 torr, 100 torr, 200 torr or 500 torr, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the growth temperature in step (2) is 500-1200°C, for example, it can be 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C or 1200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the growth reaction chamber pressure in step (2) is 20 torr to 500 torr, for example, 20 torr, 50 torr, 100 torr, 200 torr or 500 torr, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the TMAl flow rate of the growth in step (2) is 10 to 400 sccm, for example, it can be 10 sccm, 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm, 350 sccm or 400 sccm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the growth in step (2) is carried out under the condition of introducing ammonia gas.

[0034] Preferably, the flow rate of ammonia gas is 0.5-100 slm, for example, 0.5 slm, 1 slm, 5 slm, 10 slm, 25 slm, 50 slm, 75 slm or 100 slm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] As a preferred technical solution of the preparation method described in the second aspect of the present invention, the preparation method comprises the following steps:

[0036] (1) growing a buffer layer on the surface of the substrate at a temperature of 500 to 1200° C. and a reaction chamber pressure of 20 torr to 500 torr;

[0037] (2) Under the conditions of a temperature of 500 to 1200° C., a reaction chamber pressure of 20 torr to 500 torr, and a TMAl flow rate of 10 to 400 sccm, ammonia gas with a flow rate of 0.5 to 50 slm is introduced to grow a stress adjustment layer on the surface of the obtained buffer layer.

[0038] In a third aspect, the present invention provides a power device, wherein the power device comprises the gallium nitride semiconductor epitaxy as described in the first aspect.

[0039] In a fourth aspect, the present invention provides a radio frequency device, wherein the radio frequency device comprises the gallium nitride semiconductor epitaxy as described in the first aspect.

[0040] According to the above technical scheme, the beneficial effects of the present invention are as follows:

[0041] (1) The present invention grows a buffer layer between the substrate and the stress adjustment layer, wherein the buffer layer contains semiconductor material, thereby alleviating the screw and knife-edge dislocations caused by lattice mismatch and thermal mismatch between the substrate and the stress adjustment layer, and reducing the dissolution of gallium, thereby improving the quality of the crystal and showing a higher voltage resistance.

[0042] (2) The gallium nitride semiconductor epitaxy provided by the present invention has a reasonable lattice modulation capability, so that the film obtains a better strain tension, thereby achieving dislocation reduction.

[0043] (3) The buffer layer containing doped materials provided by the present invention introduces deep energy level defects to form electron traps, and a high resistance layer can be obtained by a P-type doping compensation method, which is beneficial to the subsequent growth of high-quality crystals and high resistance layers of gallium nitride semiconductors. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic structural diagram of the gallium nitride semiconductor epitaxy described in the present invention.

[0045] Among them, 1 is substrate, 2 is buffer layer, and 3 is stress adjustment layer. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0047] Example 1

[0048] This embodiment provides a gallium nitride semiconductor epitaxy ( Figure 1 ), the gallium nitride semiconductor epitaxy includes a stacked substrate 1, a buffer layer 2 and a stress adjustment layer 3.

[0049] The material of the substrate 1 is Al2O3, and the thickness of the substrate 1 is 350 μm.

[0050] The buffer layer 2 includes a semiconductor material AlN and a doping material Mg3N2, and the doping concentration of the doping element Mg in the buffer layer 2 is 1.0×E18atoms / cm 3 , the thickness of the buffer layer 2 is 250nm.

[0051] The stress adjustment layer 3 includes AlN and has a thickness of 15 μm.

[0052] The method for preparing the gallium nitride semiconductor epitaxy comprises the following steps:

[0053] (1) growing a buffer layer 2 on the surface of a substrate 1 at a temperature of 800° C. and a reaction chamber pressure of 260 torr;

[0054] (2) Under the conditions of a temperature of 800° C., a reaction chamber pressure of 260 torr, and a TMAl flow rate of 200 sccm, ammonia gas with a flow rate of 25 slm is introduced to grow a stress adjustment layer 3 on the surface of the obtained buffer layer 2.

[0055] Example 2

[0056] This embodiment provides a gallium nitride semiconductor epitaxy ( Figure 1 ), the gallium nitride semiconductor epitaxy includes a stacked substrate 1, a buffer layer 2 and a stress adjustment layer 3.

[0057] The material of the substrate 1 is GaN, and the thickness of the substrate 1 is 300 μm.

[0058] The buffer layer 2 includes semiconductor material AlN and doping material Fe6N2, and the doping concentration of doping element Fe in the buffer layer 2 is 1.0×E17atoms / cm 3 , the thickness of the buffer layer 2 is 1 nm.

[0059] The stress adjustment layer 3 includes AlInGaN and has a thickness of 1 μm.

[0060] The method for preparing the gallium nitride semiconductor epitaxy comprises the following steps:

[0061] (1) growing a buffer layer 2 on the surface of a substrate 1 at a temperature of 500° C. and a reaction chamber pressure of 500 torr;

[0062] (2) Under the conditions of a temperature of 500° C., a reaction chamber pressure of 500 torr, and a TMAl flow rate of 400 sccm, ammonia gas with a flow rate of 100 slm is introduced to grow a stress adjustment layer 3 on the surface of the obtained buffer layer 2.

[0063] Example 3

[0064] This embodiment provides a gallium nitride semiconductor epitaxy ( Figure 1 ), the gallium nitride semiconductor epitaxy includes a stacked substrate 1, a buffer layer 2 and a stress adjustment layer 3.

[0065] The material of the substrate 1 is GaO, and the thickness of the substrate 1 is 500 μm.

[0066] The buffer layer 2 includes semiconductor material AlN and doping material Be3N2, and the doping concentration of the doping element Be in the buffer layer 2 is 1.0×E19atoms / cm 3 , the thickness of the buffer layer 2 is 1000 nm.

[0067] The stress adjustment layer 3 includes AlGaN and has a thickness of 30 μm.

[0068] The method for preparing the gallium nitride semiconductor epitaxy comprises the following steps:

[0069] (1) growing a buffer layer 2 on the surface of a substrate 1 at a temperature of 1200° C. and a reaction chamber pressure of 20 torr;

[0070] (2) Under the conditions of a temperature of 1200° C., a reaction chamber pressure of 20 torr, and a TMAl flow rate of 10 sccm, ammonia gas with a flow rate of 0.5 slm is introduced to grow a stress adjustment layer 3 on the surface of the obtained buffer layer 2.

[0071] Example 4

[0072] This embodiment provides a gallium nitride semiconductor epitaxy, which is the same as Embodiment 1 except that the doping material Mg3N2 is replaced by graphite.

[0073] Example 5

[0074] This embodiment provides a gallium nitride semiconductor epitaxy, except that the doping concentration of the doping element Mg in the buffer layer is 8.0×E16atoms / cm 3 Except for this, the other composition contents and process parameters are the same as those in Example 1.

[0075] Example 6

[0076] This embodiment provides a gallium nitride semiconductor epitaxy, except that the doping concentration of the doping element Mg in the buffer layer is 1.2×E19atoms / cm 3 Except for this, the other composition contents and process parameters are the same as those in Example 1.

[0077] Example 7

[0078] This embodiment provides a gallium nitride semiconductor epitaxy. Except that the thickness of the buffer layer is 0.5 nm, the remaining composition contents and process steps are the same as those of Embodiment 1.

[0079] Example 8

[0080] This embodiment provides a gallium nitride semiconductor epitaxy. Except that the thickness of the buffer layer is 1050 nm, the remaining composition contents and process steps are the same as those of Embodiment 1.

[0081] Example 9

[0082] This embodiment provides a gallium nitride semiconductor epitaxy. Except that the doping material Mg3N2 is replaced by Ca3N2 with the same doping concentration, the other composition contents and process parameters are the same as those in Embodiment 1.

[0083] Example 10

[0084] This embodiment provides a gallium nitride semiconductor epitaxy. Except that the doping material Mg3N2 is replaced by CoN with the same doping concentration, the other composition contents and process parameters are the same as those in Embodiment 2.

[0085] Embodiment 11

[0086] This embodiment provides a gallium nitride semiconductor epitaxy. Except that the doping material graphite is replaced by Si with the same doping concentration, the other composition contents and process parameters are the same as those of Embodiment 4.

[0087] Example 12

[0088] This embodiment provides a gallium nitride semiconductor epitaxy. Except that the buffer layer does not contain doping materials, the remaining composition contents and process parameters are the same as those of Embodiment 1.

[0089] Embodiment 13

[0090] This embodiment provides a gallium nitride semiconductor epitaxy. Except for replacing the semiconductor material AlN in the buffer layer with an equal amount of AlInN, the remaining composition content and process parameters are the same as those in Embodiment 1.

[0091] Comparative Example 1

[0092] This comparative example provides a gallium nitride semiconductor epitaxy, which has the same composition content and process parameters as those of Example 1 except that it does not contain a buffer layer.

[0093] Comparative Example 2

[0094] This comparative example provides a gallium nitride semiconductor epitaxy. Except for replacing the semiconductor material AlN in the buffer layer with an equal amount of Al2O3, the remaining composition content and process parameters are the same as those in Example 1.

[0095] Comparative Example 3

[0096] This comparative example provides a gallium nitride semiconductor epitaxy. Except for replacing the semiconductor material AlN in the buffer layer with an equal amount of Si, the remaining composition contents and process parameters are the same as those in Example 1.

[0097] Comparative Example 4

[0098] This comparative example provides a gallium nitride semiconductor epitaxy. Except for replacing the semiconductor material AlN in the buffer layer with an equal amount of AlInGaN, the remaining composition contents and process parameters are the same as those in Example 1.

[0099] Comparative Example 5

[0100] This comparative example provides a gallium nitride semiconductor epitaxy. Except for replacing the semiconductor material AlN in the buffer layer with an equal amount of AlGaN, the other composition contents and process parameters are the same as those in Example 1.

[0101] Comparative Example 6

[0102] This comparative example provides a gallium nitride semiconductor epitaxy. Except for replacing the semiconductor material AlN in the buffer layer with an equal amount of GaO, the other composition contents and process parameters are the same as those in Example 1.

[0103] The following conclusions can be drawn from the obtained GaN semiconductor epitaxy:

[0104] (1) It can be seen from Examples 1-4 and 13 that the present invention, by growing a buffer layer between the substrate and the stress adjustment layer, wherein the buffer layer contains semiconductor material and adds doping material, mitigates the screw and edge dislocations caused by lattice mismatch and thermal mismatch between the substrate and the stress adjustment layer, and reduces the dissolution of gallium, thereby improving the quality of the crystal and showing a higher voltage resistance.

[0105] (2) From the comparison between Examples 5 and 6 and Example 1, it can be seen that when the doping concentration is not between 1.0×E17 and 1.0×E19 atoms / cm 3 When the thickness is too high, the withstand voltage of the resulting gallium nitride semiconductor epitaxy decreases and the crystal quality is poor.

[0106] (3) Comparison between Examples 7 and 8 and Example 1 shows that when the thickness of the buffer layer is not within the range of 1 to 1000 nm, the withstand voltage of the resulting gallium nitride semiconductor epitaxy is reduced and the crystal quality is poor.

[0107] (4) Comparison of Examples 9-11 with Example 1 shows that when the doping element is not carbon, beryllium, magnesium or iron, the withstand voltage of the resulting gallium nitride semiconductor epitaxy is reduced and the crystal quality is poor.

[0108] (5) From the comparison between Example 12 and Example 1, it can be seen that when no doping is performed, the withstand voltage of the obtained gallium nitride semiconductor epitaxy is reduced and the crystal quality is poor.

[0109] (6) From the comparison between Comparative Example 1 and Example 1, it can be seen that when there is no buffer layer, the withstand voltage of the obtained gallium nitride semiconductor epitaxy is reduced and the crystal quality is poor.

[0110] (7) From the comparison between Comparative Examples 2-6 and Example 1, it can be seen that when the semiconductor material in the buffer layer is replaced, the withstand voltage of the obtained gallium nitride semiconductor epitaxy is reduced and the crystal quality is poor.

[0111] In summary, the present invention grows a buffer layer between the substrate and the stress adjustment layer, wherein the buffer layer contains semiconductor material and is undoped or has added doping materials, thereby alleviating the spiral and edge dislocations caused by lattice mismatch and thermal mismatch between the substrate and the stress adjustment layer, and reducing the dissolution of gallium, thereby improving the quality of the crystal and showing a higher voltage resistance.

[0112] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A gallium nitride semiconductor epitaxy, characterized in that: The gallium nitride semiconductor epitaxy comprises a stacked substrate, a buffer layer and a stress adjustment layer; The buffer layer comprises a semiconductor material; The semiconductor material includes AlN and / or AlInN; The buffer layer includes a doping material, which includes any one or a combination of at least two of the elements carbon, beryllium, magnesium and iron. The doping concentration of the doping material in the buffer layer is 1.0×E17 to 1.0×E19 atoms / cm 3 .

2. The gallium nitride semiconductor epitaxy according to claim 1, characterized in that: The substrate includes any one of Al2O3, GaN, AlN, Si, GaO or SiC, or a combination of at least two thereof.

3. The gallium nitride semiconductor epitaxy according to claim 1, characterized in that: The stress adjustment layer includes any one of AlN, GaN, AlGaN or AlInGaN, or a combination of at least two of them.

4. The gallium nitride semiconductor epitaxy according to claim 1, characterized in that: The thickness of the substrate is greater than 300 μm.

5. The gallium nitride semiconductor epitaxy according to claim 1, characterized in that: The thickness of the buffer layer is 1-1000 nm.

6. The gallium nitride semiconductor epitaxy according to claim 1, characterized in that: The thickness of the stress adjustment layer is 1-30 μm.

7. The method for preparing gallium nitride semiconductor epitaxy according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) growing a buffer layer on the surface of the substrate; (2) A stress adjustment layer is grown on the surface of the obtained buffer layer.

8. The preparation method according to claim 7, characterized in that: The growth temperature in step (1) is 500-1200°C.

9. The preparation method according to claim 7, characterized in that: The growth reaction chamber pressure in step (1) is 20 to 500 torr.

10. The preparation method according to claim 7, characterized in that: The growth temperature in step (2) is 500-1200°C.

11. The preparation method according to claim 7, characterized in that: The growth reaction chamber pressure in step (2) is 20 to 500 torr.

12. The preparation method according to claim 7, characterized in that: The TMAl flow rate of the growth in step (2) is 10 to 400 sccm.

13. The preparation method according to claim 7, characterized in that: The growth in step (2) is carried out under the condition of introducing ammonia gas.

14. The preparation method according to claim 13, characterized in that: The flow rate of the ammonia gas is 0.5-100 slm.

15. The preparation method according to claim 7, characterized in that: The preparation method comprises the following steps: (1) growing a buffer layer on the surface of the substrate at a temperature of 500 to 1200° C. and a reaction chamber pressure of 20 torr to 500 torr; (2) Under the conditions of a temperature of 500 to 1200° C., a reaction chamber pressure of 20 torr to 500 torr, and a TMAl flow rate of 10 to 400 sccm, ammonia gas with a flow rate of 0.5 to 100 slm is introduced to grow a stress adjustment layer on the surface of the obtained buffer layer.

16. A power device, characterized in that: The power device comprises the gallium nitride semiconductor epitaxy as claimed in any one of claims 1 to 6.

17. A radio frequency device, characterized in that: The radio frequency device contains the gallium nitride semiconductor epitaxy as described in any one of claims 1-6.

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