Diamond-based ScAlN / gallium nitride heterostructure and preparation method thereof
By setting micropillars and three ScAlN transition layers on a diamond substrate, the problems of lattice mismatch and thermal expansion coefficient difference between diamond and GaN materials were solved, and the growth of high-quality GaN epitaxial layers and efficient heat dissipation were achieved.
Patent Information
- Application Number
- CN202510883546.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-29
- Publication Date
- 2025-10-24
AI Technical Summary
There is a large lattice mismatch and difference in thermal expansion coefficient between diamond and GaN materials, which makes it difficult to grow high-quality GaN films epitaxially.
Multiple micropillars were fabricated on a diamond substrate, and GaN epitaxial layers were grown epitaxially by adjusting the Sc composition through a three-layer ScAlN transition layer to reduce lattice mismatch and thermal expansion coefficient differences.
This effectively reduces lattice mismatch and differences in thermal expansion coefficients, improves the quality and heat dissipation efficiency of GaN epitaxial layers, and reduces fabrication costs.
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Figure CN120835602A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of microelectronics, and particularly relates to a diamond-based ScAlN / gallium nitride heterostructure and a preparation method thereof. BACKGROUND
[0002] Diamond-based GaN materials based on heteroepitaxy technology are a new emerging semiconductor material, which has excellent thermal conductivity, high breakdown electric field and wide bandgap characteristics, and is considered as one of the key technologies to improve the power density and operating temperature of electronic devices. The development goal of this technology is to epitaxially grow high-quality GaN epitaxial layers on diamond substrates and apply them to the manufacturing of high-power electronic devices to break through the performance bottleneck of traditional GaN-based electronic devices. Diamond, as an ideal substrate material, has a thermal conductivity of 2000 W / (m·K), which is much higher than that of traditional SiC (490 W / (m·K)) and Si (150 W / (m·K)) substrates. This means that GaN devices based on diamond substrates can effectively dissipate heat, thereby greatly improving the power density and operating temperature of the devices. In addition, the wide bandgap characteristics of diamond also make GaN devices based on its substrate have higher breakdown voltage, which is beneficial to improve the operating voltage and power level of the device.
[0003] Heteroepitaxy technology aims to effectively reduce the lattice mismatch between diamond and GaN by introducing transition layers or buffer layers, etc., so as to obtain high-quality GaN epitaxial layers. However, there is a large lattice mismatch and thermal expansion coefficient difference between diamond and GaN materials, making it difficult to epitaxially grow high-quality GaN films. SUMMARY
[0004] In view of this, the present application provides a diamond-based ScAlN / gallium nitride heterostructure and a preparation method thereof, which reduces the lattice mismatch and thermal expansion coefficient difference by setting a microcolumn and a three-layer ScAlN transition layer between the diamond substrate and the gallium nitride epitaxial layer, so that a high-quality gallium nitride epitaxial layer can be epitaxially grown on the diamond substrate.
[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: On the one hand, the present application provides a diamond-based ScAlN / gallium nitride heterostructure, which comprises a diamond substrate, a first transition layer, a second transition layer, a third transition layer and a gallium nitride epitaxial layer, the diamond substrate has a plurality of microcolumns protruding on one side; the first transition layer is laid on the side of the diamond substrate with the plurality of microcolumns, the first transition layer is a Sc x1 AL 1-x1 N transition layer, wherein x1 is greater than 0.2 and not greater than 0.3; the second transition layer is laid on the side of the first transition layer away from the diamond substrate, the second transition layer is a Scx2 AL 1-x2 N transition layer, wherein x2 is greater than 0.1 and not greater than 0.2; the third transition layer is disposed on the side of the second transition layer away from the first transition layer, and the third transition layer is Sc x3 AL 1-x3 N transition layer, wherein x3 is equal to 0.1; the gallium nitride epitaxial layer is disposed on the side of the third transition layer away from the second transition layer.
[0006] Preferably, the thickness of the diamond substrate is 375-1000 μm, the length of the diamond is 10-50 mm, and the width of the diamond is 10-50 mm.
[0007] Preferably, the cross section of each microcolumn is circular or polygonal; and / or, The thickness of each microcolumn is 2-10 nm.
[0008] Preferably, further comprising a nitrogen-terminated diamond layer between the diamond substrate and the first transition layer, and disposed on the diamond substrate, the thickness of the nitrogen-terminated diamond layer is 2-10 nm.
[0009] Preferably, the thickness of the first transition layer is 200 nm; and / or, The thickness of the second transition layer is 100 nm; and / or, The thickness of the third transition layer is 20 nm; and / or, The thickness of the gallium nitride epitaxial layer is 400 nm.
[0010] In another aspect, the present application provides a preparation method of the heterostructure, the diamond-based ScAlN / gallium nitride heterostructure comprising a nitrogen-terminated diamond layer, the preparation method of the diamond-based ScAlN / gallium nitride heterostructure comprising the following steps: S1, etching a plurality of microcolumns on one side of the diamond substrate; S2, epitaxially growing a nitrogen-terminated diamond layer on the side of the diamond substrate provided with the plurality of microcolumns; S3, epitaxially growing a first transition layer, a second transition layer, a third transition layer and a gallium nitride epitaxial layer in sequence on the side of the nitrogen-terminated diamond layer away from the diamond substrate, to obtain a diamond-based ScAlN / gallium nitride heterostructure.
[0011] Preferably, in step S2, the specific method for epitaxially growing the nitrogen-terminated diamond layer is: placing the side of the diamond substrate provided with the microcolumns in a nitrogen atmosphere at a temperature of 850-1000℃ for 20-25 min.
[0012] Preferably, in step S3, the forming method of the first transition layer, the second transition layer and the third transition layer is: under vacuum condition, proportionally introducing gas Sc(Cp)2, Al(CH3)3 and NH3, and growing Sc(Cp)2, Al(CH3)3 and NH3 on the side of the nitrogen-terminated diamond layer far from the diamond substrate.
[0013] Preferably, mass flow controllers are used to introduce gas Sc(Cp)2, Al(CH3)3 and NH3, so as to control the amount and flow rate of the introduction of Sc(Cp)2, Al(CH3)3 and NH3.
[0014] Preferably, in step S3, the preparation method of the gallium nitride epitaxial layer is: using a molecular beam epitaxy device to grow the gallium nitride epitaxial layer on the third transition layer, and the parameters of the molecular beam epitaxy device are set as follows: temperature is 670-720℃, nitrogen flow is 2.3sccm, gallium beam current is 6.0×10 -7 -8.0×10 -7 Torr, and nitrogen radio frequency source power is 375W.
[0015] Compared with the prior art, the present application has the following beneficial effects: (1) Firstly, a plurality of micro columns are arranged on the diamond substrate, the reason for arranging the micro columns is that there is a large difference between the lattice constant (a = 3.567 Å) of diamond and the lattice constant of ScAlN, and direct ScAlN heteroepitaxial growth on the diamond substrate will cause obvious lattice mismatch, thereby forming stress, dislocation and defects. Through the patterning etching of the ICP device (inductively coupled plasma device), a plurality of island-shaped micro columns are reserved on the surface of the diamond substrate, thereby reducing the distortion degree and reducing defects. Secondly, three layers of ScALN transition layers are arranged between the diamond substrate and the gallium nitride epitaxial layer, the Sc content in each ScALN transition layer is different, and the purpose of this arrangement is that: through pulse epitaxial growth, a plurality of lattice gradient ScAlN layers with different Sc components are obtained, when the Sc component of ScAlN is between 10% and 30%, the physical and chemical properties are relatively stable. And when the Sc component in ScAlN increases from 10% to 30%, the c-axis lattice constant of ScAlN increases from 4.93 to 5.10 Å. By increasing the Sc component of ScAlN, the lattice mismatch between diamond and ScAlN can be reduced, and the heat dissipation efficiency and electrical conductivity of the material can be improved. The Sc component of the uppermost ScAlN layer is designed to be 10%, so that it has the closest lattice constant to the GaN epitaxial layer, and the GaN epitaxial layer is epitaxially grown on the surface thereof, thereby reducing the stress mismatch between ScAlN and GaN, and ensuring the quality and electrical properties of the GaN heterojunction material. In short, by arranging the micro columns and the three layers of ScAlN transition layers, the lattice mismatch and the difference in the thermal expansion coefficient are reduced, so that a high-quality gallium nitride epitaxial layer can be epitaxially grown on the diamond substrate.
[0016] (2) By optimizing the size and arrangement mode of the diamond micro columns, the stress generated during the growth of the epitaxial layer can be effectively released, thereby reducing the formation of defects.
[0017] (3) A nitrogen terminal diamond layer is epitaxially grown on one side of the diamond substrate provided with a plurality of micro columns, specifically, the diamond is subjected to N terminal processing by adding nitrogen-containing gas (such as ammonia) into the diamond lattice, so as to further reduce the lattice constant of the diamond and effectively reduce the lattice mismatch between the diamond substrate and ScAlN.
[0018] (4) The ScAlN / GaN is prepared on the diamond substrate by a direct heteroepitaxial growth method, and the cost of the diamond-based GaN prepared by the method is lower than that of the method of laser stripping and secondary bonding, Y metal as a transition layer heteroepitaxy, and the method is simple.
[0019] (5) The thermal conductivity of ScAlN is usually between 200-300 W / m·K, which is higher than that of AlN, GaN and other materials, and as a transition layer between GaN and diamond, the high thermal conductivity of diamond can be effectively utilized. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 Schematic diagram of the structure of a diamond-based ScAlN / GaN heterostructure provided by one embodiment of the present invention.
[0021] Reference numerals: diamond-based ScAlN / gallium nitride heterostructure 100 , diamond substrate 1 , micropillars 11 , first transition layer 2 , second transition layer 3 , third transition layer 4 , gallium nitride epitaxial layer 5 , nitrogen-terminated diamond layer 6 . DETAILED DESCRIPTION
[0022] The present invention will be further described in detail below with reference to specific embodiments so that those skilled in the art can understand the present invention more clearly.
[0023] Diamond-based GaN material, based on heteroepitaxial growth technology, is an emerging semiconductor material with excellent thermal conductivity, high breakdown electric field, and wide bandgap characteristics. It is considered one of the key technologies for improving the power density and operating temperature of electronic devices. The development goal of this technology is to epitaxially grow high-quality GaN epitaxial layers on diamond substrates and apply them to the manufacture of high-power electronic devices to break through the performance bottleneck of traditional GaN-based electronic devices. As an ideal substrate material, diamond has a thermal conductivity of up to 2000W / (m·K), which is much higher than traditional SiC (490W / (m·K)) and Si (150W / (m·K)) substrates. This means that GaN devices based on diamond substrates can effectively dissipate heat, thereby significantly improving the power density and operating temperature of the devices. In addition, the wide bandgap characteristics of diamond also give GaN devices based on its substrate a higher breakdown voltage, which is conducive to improving the operating voltage and power level of the devices.
[0024] Heteroepitaxial growth technology aims to effectively reduce the lattice mismatch between diamond and GaN by introducing transition layers or buffer layers, thereby producing high-quality GaN epitaxial layers. However, the large lattice mismatch and thermal expansion coefficient differences between diamond and GaN materials make epitaxial growth of high-quality GaN films difficult.
[0025] Based on the above problems, combined with the attached Figure 1 The present invention provides a diamond-based ScAlN / GaN heterostructure 100, comprising a diamond substrate 1, a first transition layer 2, a second transition layer 3, a third transition layer 4, and a GaN epitaxial layer 5. A plurality of micropillars 11 are formed on one side of the diamond substrate 1; the first transition layer 2 is applied on the side of the diamond substrate 1 having the plurality of micropillars 11; the first transition layer 2 is ScAlN. x1 AL 1-x1a first transition layer 2 of ScAlN, where x1 is greater than 0.2 and not greater than 0.3; the second transition layer 3 is disposed on a side of the first transition layer 2 distal from the diamond substrate 1, the second transition layer 3 being of ScAlN x2 AL 1-x2 a third transition layer 4 of ScAlN, where x2 is greater than 0.1 and not greater than 0.2; the third transition layer 4 is disposed on a side of the second transition layer 3 distal from the first transition layer 2, the third transition layer 4 being of ScAlN x3 AL 1-x3 a fourth transition layer 5 of ScAlN, where x3 is equal to 0.1; the gallium nitride epitaxial layer 5 is disposed on a side of the third transition layer 4 distal from the second transition layer 3.
[0026] In the above technical solution, the diamond substrate 1 is a single crystal diamond, which has the advantages of high thermal conductivity, high mechanical strength, excellent chemical stability, low thermal expansion coefficient, and high electron mobility; the first transition layer 2 is Sc x1 AL 1-x1 a first transition layer 2 of ScAlN, where x1 is greater than 0.2 and not greater than 0.3; in some embodiments, x1 is 0.3 or about 0.29, 0.28, i.e., x1 is closer to 0.3. The second transition layer 3 is Sc x2 AL 1-x2 a third transition layer 4 of ScAlN, where x2 is greater than 0.1 and not greater than 0.2; in some embodiments, x2 is 0.2 or about 0.18, 0.19, i.e., x2 is closer to 0.2. The third transition layer 4 is disposed on a side of the second transition layer 3 distal from the first transition layer 2, the third transition layer 4 being of ScAlN x3 AL 1-x3 a fourth transition layer 5 of ScAlN, where x3 is equal to 0.1.
[0027] The application has the beneficial effects of the above technical solutions: first, the application first provides a plurality of micro columns 11 on the diamond substrate 1. The reason for providing the micro columns 11 is that there is a large difference between the lattice constant (a = 3.567 Å) of diamond and the lattice constant of ScAlN. Direct ScAlN heteroepitaxial growth on the diamond substrate 1 will cause obvious lattice mismatch, thereby forming stress, dislocations and defects. Through the patterned etching of an ICP device (inductively coupled plasma device), a plurality of island-shaped micro columns 11 are reserved on the surface of the diamond substrate 1, thereby reducing the distortion degree and reducing defects. Second, three layers of ScALN transition layers are provided between the diamond substrate 1 and the gallium nitride epitaxial layer 5. The Sc content in each layer of ScALN transition layer is different. The purpose of this setting is to grow a plurality of layers of lattice-graded ScAlN with different Sc components by pulse epitaxy. When the Sc component of ScAlN is between 10% and 30%, the physical and chemical properties are relatively stable. When the Sc component of ScAlN increases from 10% to 30%, the c-axis lattice constant of ScAlN increases from 4.93 to 5.10 Å. By increasing the Sc component of ScAlN, the lattice mismatch between diamond and ScAlN can be reduced, and the heat dissipation efficiency and electrical conductivity of the material can be improved. The Sc component of the uppermost layer of ScAlN is designed to be 10%, so that it has the closest lattice constant to the GaN epitaxial layer, and the GaN epitaxial layer is epitaxially grown on its surface, thereby reducing the stress mismatch between ScAlN and GaN, and ensuring the quality and electrical properties of the GaN heterojunction material. In short, by providing the micro columns 11 and the three layers of ScAlN transition layers, the lattice mismatch and the difference in the thermal expansion coefficient are reduced, so that the diamond substrate 1 can epitaxially grow a high-quality gallium nitride epitaxial layer 5. Second, by optimizing the size and arrangement of the diamond micro columns 11, the stress generated during the growth of the epitaxial layer can be effectively released, thereby reducing the formation of defects. Third, the application prepares ScAlN / GaN on the diamond substrate 1 by a direct heteroepitaxial growth method, which has a lower cost and a simpler method than the methods of laser lift-off and secondary bonding after laser lift-off, Y metal as a transition layer, and heteroepitaxy. Fourth, the thermal conductivity of ScAlN is usually between 200-300 W / m·K, which is higher than that of materials such as AlN and GaN. As a transition layer between GaN and diamond, it can effectively utilize the high thermal conductivity of diamond.
[0028] Further, the thickness of the diamond substrate 1 is 375-1000 μm, the length of the diamond is 10-50 mm, and the width of the diamond is 10-50 mm. Reasonable size of the diamond substrate 1 enables the diamond substrate 1 to be better integrated with other heterostructures (such as ScAlN and gallium nitride), thereby improving the overall performance of the heterostructure, especially in optoelectronic and high-power electronic devices.
[0029] Further, the cross section of each micro column 11 is circular or polygonal, which has obvious advantages in improving the bonding force between the diamond substrate 1 and the epitaxial layer, optimizing the heat dissipation performance, improving the mechanical strength, reducing the stress concentration, and promoting the epitaxial growth quality. In some embodiments, the thickness of each micro column 11 is 2-10 nm, which helps to improve the interface quality between the diamond substrate 1 and the epitaxial layer, optimize the heat management performance, reduce the stress concentration, and improve the crystal quality of the epitaxial layer and the electrical and optical performance of the device. The micro column 11 structure with small thickness not only helps to improve the production precision, but also can reduce material waste, reduce cost, and improve the long-term stability and reliability of the device.
[0030] Further, a nitrogen-terminated diamond layer 6 is further included between the diamond substrate 1 and the first transition layer 2 and is coated on the diamond substrate 1, and the thickness of the nitrogen-terminated diamond layer 6 is 2-10 nm. By optimizing the size and arrangement of the diamond micro column 11, the present application can effectively release the stress generated during the growth of the epitaxial layer, thereby reducing the formation of defects.
[0031] In some embodiments, the thickness of the first transition layer 2 is 200 nm; in some embodiments, the thickness of the second transition layer 3 is 100 nm; in some embodiments, the thickness of the third transition layer 4 is 20 nm; and in some embodiments, the thickness of the gallium nitride epitaxial layer 5 is 400 nm. The thickness design (200 nm, 100 nm, 20 nm, and 400 nm) of each layer of transition layer and gallium nitride epitaxial layer 5 has important advantages in optimizing stress relief, improving epitaxial layer quality, improving heat management, improving electrical performance, and enhancing device stability. In particular, the design of layer-by-layer transition helps to reduce lattice mismatch and thermal expansion difference, improve device reliability, performance, and production efficiency.
[0032] The present application also provides a preparation method of the heterostructure. The diamond-based ScAlN / gallium nitride heterostructure 100 includes a nitrogen-terminated diamond layer 6, and the preparation method of the diamond-based ScAlN / gallium nitride heterostructure 100 includes the following steps: S1, etching a plurality of micro columns 11 on one side of the diamond substrate 1; In some embodiments, a high-quality single-crystal diamond is selected as a heat dissipation substrate, and the size is 10*10*0.5mm. First, the diamond surface is cleaned using solvents such as acetone and alcohol to remove oil stains and impurities. Second, the diamond surface is preliminarily polished using coarse-grained diamond sandpaper or abrasive, and larger surface defects are removed. Then, the surface is further refined using fine-grained diamond sandpaper or abrasive, and the process is repeated multiple times to gradually reduce the surface roughness.
[0033] The chemical mechanical polishing slurry containing diamond particles, oxidizing agent and stabilizer is prepared by chemical mechanical polishing method. The oxidizing agent (such as nitric acid) helps to remove the small protrusions on the surface, and the stabilizer controls the polishing rate and the stability of the slurry. The diamond sample is placed in the CMP device (chemical polishing device), and by rotating and applying a certain pressure, the chemical reaction and mechanical action are used together to further reduce the surface roughness, and finally the roughness of the diamond reaches 0.2 nm. First, the photoresist is coated on the diamond substrate 1, then the photoetching and development are carried out to mask the diamond micropillar 11 area to be etched, the Ni metal is magnetron sputtered, and the definition of the etched diamond micropillar 11 pattern is stripped, and the length and width of the micropillar 11 are about 200x200um. Optionally, the etching mask layer at this time can also be Si3N4, SiO2 and other media or W, Cr and other metals. Then, the diamond is patterned and etched using an ICP device (inductively coupled plasma device), the oxygen flow is 200sccm, the direct current power is 1000W, the alternating current power is 150W, the etching time is 5min, and the diamond etching depth is about 10-50nm. Finally, the surface Ni mask is removed by inorganic solution cleaning, and the diamond micropillar 11 pattern is completed.
[0034] S2, a nitrogen terminal diamond layer 6 is epitaxially grown on one side of the diamond substrate 1 provided with a plurality of micropillars 11; In some embodiments, the diamond is loaded onto a special customized molybdenum holder of the MBE device, the heater is started, and the diamond is heated to a predetermined 850°C. During the nitrogen terminal processing, the temperature control is very important, and needs to be accurately controlled within a specific range of 850°C-1000°C. Secondly, the nitrogen supply system is opened, and high-purity nitrogen (usually 99.999% or higher purity) is injected into the MBE device. The flow and pressure of the nitrogen are adjusted to form a uniform nitrogen atmosphere on the surface of the diamond substrate 1, and the processing time is 20-25min. In some embodiments, the processing time is 20min.
[0035] S3, a first transition layer 2, a second transition layer 3, a third transition layer 4 and a gallium nitride epitaxial layer 5 are sequentially epitaxially grown on the side of the nitrogen terminal diamond layer 6 away from the diamond substrate 1, to obtain a diamond-based ScAlN / gallium nitride heterostructure 100.
[0036] In some embodiments, the nitrogen-terminated diamond substrate 1 is slowly warmed to the ScAlN growth temperature (usually at 700℃), the precursors of Sc, Al and N (Sc(Cp)2, Al(CH3)3, NH3) are precisely controlled by mass flow controllers (MFC) and introduced into the vacuum chamber through injection tubes, while monitoring the reaction pressure and temperature to ensure the stability of the growth environment. The growth temperature of ScAlN is usually high, and the temperature needs to be precisely controlled to avoid phase separation and defects. By adjusting the flow ratio of Sc, Al and N, the Sc component is precisely controlled at about 30%, the growth rate is controlled within a suitable range (usually 0.1 to 1.0 μm / h), and the growth time is adjusted to control the Sc 0.3 Al 0.7 N epitaxial thickness is 200 nm. By adjusting the flow ratio of Sc, Al and N, the Sc component is precisely controlled at about 20%, the growth rate is controlled within a suitable range, and the growth time is adjusted to control the Sc 0.2 Al 0.8 N epitaxial thickness is 100 nm. By adjusting the flow ratio of Sc, Al and N, the Sc component is precisely controlled at about 10%, the growth rate is controlled within a suitable range, and the growth time is adjusted to control the Sc 0.2 Al 0.8 N epitaxial thickness is 20 nm. Using molecular beam epitaxy, the temperature is set to 670-720℃, the nitrogen flow is 2.3sccm, the gallium beam current is balanced at a vapor pressure of 6.0x10 -7 -8.0x10 -7 Torr, and the nitrogen radio frequency source power is 375W. A 400nm --GaN epitaxial layer is grown on the transition layer to complete the material preparation.
[0037] The diamond-based ScAlN / gallium nitride heterostructure 100 prepared by the method effectively reduces the lattice mismatch between diamond and ScAlN, ScAlN epitaxial growth, and ScAlN and GaN materials, reduces material growth stress, and can obtain high-quality diamond-based gallium nitride materials.
[0038] The specific raw materials in the present application are all existing substances and can be directly purchased from the market.
[0039] The above merely preferred embodiments of the present application and are not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A diamond-based ScAIN / gallium nitride heterostructure, characterized in that, The diamond substrate has a plurality of micro-pillars formed on one side thereof; The gallium nitride epitaxial layer is disposed on the third transition layer away from the second transition layer. a first transition layer disposed on a side of the diamond substrate having the plurality of micro-pillars, the first transition layer being Sc x1 AL 1-x1 N transition layer, wherein x1 is greater than 0.2 and not greater than 0.3; a second transition layer disposed on a side of the first transition layer distal from the diamond substrate, the second transition layer being Sc x2 AL 1-x2 N transition layer, wherein x2 is greater than 0.1 and not greater than 0.2; a third transition layer disposed on a side of the second transition layer distal from the first transition layer, the third transition layer being Sc x3 AL 1-x3 N transition layer, wherein x3 is equal to 0.1; The thickness of the diamond substrate is 375-1000 μm, the length of the diamond is 10-50 mm, and the width of the diamond is 10-50 mm.
2. The heterostructure of claim 1, wherein, The cross section of each micro-pillar is circular or polygonal; and / or, 3. The heterostructure of claim 1, wherein, The thickness of each micro-pillar is 2-10 nm. A nitrogen-terminated diamond layer is further included between the diamond substrate and the first transition layer and is disposed on the diamond substrate, and the thickness of the nitrogen-terminated diamond layer is 2-10 nm.
4. The heterostructure of claim 1, wherein, The thickness of the first transition layer is 200 nm; and / or, 5. The heterostructure of claim 1, wherein, The thickness of the second transition layer is 100 nm; and / or, The thickness of the third transition layer is 20 nm; and / or, The thickness of the gallium nitride epitaxial layer is 400 nm. The diamond-based ScAlN / gallium nitride heterostructure includes a nitrogen-terminated diamond layer, and a preparation method of the diamond-based ScAlN / gallium nitride heterostructure includes the following steps:
6. The method for preparing a heterostructure according to any one of claims 1 to 5, characterized in that: S1. A plurality of micro-pillars are etched on one side of the diamond substrate; S2. A nitrogen-terminated diamond layer is epitaxially formed on the side of the diamond substrate provided with the plurality of micro-pillars; S3. A first transition layer, a second transition layer, a third transition layer and a gallium nitride epitaxial layer are epitaxially formed in sequence on the side of the nitrogen-terminated diamond layer away from the diamond substrate, to obtain a diamond-based ScAlN / gallium nitride heterostructure. In step S2, the specific method for epitaxially forming the nitrogen-terminated diamond layer is that the side of the diamond substrate provided with the micro-pillars is placed in a nitrogen atmosphere at a temperature of 850-1000 °C for 20-25 min.
7. The production method according to claim 6, characterized by, In step S3, the formation methods of the first transition layer, the second transition layer and the third transition layer are all that, under vacuum conditions, the gases Sc(Cp)2, Al(CH3)3 and NH3 are introduced in proportion, so that Sc(Cp)2, Al(CH3)3 and NH3 grow on the side of the nitrogen-terminated diamond layer away from the diamond substrate.
8. The preparation method according to claim 6, characterized in that The gases Sc(Cp)2, Al(CH3)3 and NH3 are introduced by using a mass flow controller, so as to control the amount and flow rate of the introduced Sc(Cp)2, Al(CH3)3 and NH3.
9. The production method according to claim 8, characterized by, 10. The method of claim 6, wherein, In step S3, the gallium nitride epitaxial layer is prepared by using a molecular beam epitaxy device to grow the gallium nitride epitaxial layer on the third transition layer, wherein the molecular beam epitaxy device is set to have a temperature of 670-720℃, a nitrogen flow rate of 2.3sccm, a gallium beam current equilibrium vapor pressure of 6.0×10 -7 -8.0×10 -7 Torr, and a nitrogen radio frequency source power of 375W. In step S4, the gallium nitride epitaxial layer is prepared by using a metal organic chemical vapor deposition device to grow the gallium nitride epitaxial layer on the third transition layer, wherein the metal organic chemical vapor deposition device is set to have a temperature of 650-750℃, a trimethylgallium flow rate of 2.0sccm, a ammonia flow rate of 2.0sccm, a hydrogen flow rate of 2.0sccm, a trimethylgallium flow rate of 2.0sccm, a nitrogen radio frequency source power of 375W, and a pressure of 2.0×10