High-thermal-conductivity gallium oxide composite substrate and preparation method and application thereof

Abstract

The invention provides a high-thermal-conductivity gallium oxide composite substrate and a preparation method and application thereof. The method comprises the following steps: (1) epitaxially growing a gallium oxide single crystal film on a sapphire substrate; (2) growing an MgO sacrificial layer on the gallium oxide single crystal thin film; (3) growing a gallium oxide single crystal on the MgO sacrificial layer to obtain a gallium oxide wafer; (4) transferring the gallium oxide wafer to a high-thermal-conductivity substrate in a wafer bonding mode; and (5) carrying out wet etching on the MgO sacrificial layer, and polishing and grinding one surface, in contact with the MgO sacrificial layer, of the gallium oxide wafer to obtain the high-thermal-conductivity gallium oxide composite substrate. According to the method, the MgO sacrificial layer is firstly formed, then wet etching is performed, the adopted process is simple, the equipment requirement is low, the production efficiency is high, and the production cost is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a high thermal conductivity gallium oxide composite substrate, a preparation method thereof, and applications thereof. Background Art

[0002] Gallium oxide, an ultra-wide bandgap semiconductor material that has rapidly developed in recent years, boasts a wider bandgap and higher breakdown field strength than previous generations of semiconductor materials, including silicon, germanium, gallium arsenide, and gallium nitride. This offers significant advantages in the fabrication of high-temperature, high-voltage, and radiation-resistant power electronic devices. However, gallium oxide's extremely low thermal conductivity has become a significant bottleneck restricting the use of its electronic devices in high-power applications. This low thermal conductivity of gallium oxide has resulted in heat being primarily concentrated near the gallium oxide material and electrodes in currently fabricated gallium oxide electronic devices. Under high voltage conditions, this heat accumulation severely impacts device stability and reliability.

[0003] Currently, some solutions have been proposed to address the heat dissipation problem of gallium oxide power devices. For example, for devices prepared by homoepitaxial growth, substrate thinning or external heat dissipation systems can be used to reduce thermal resistance, but the yield and reliability will be significantly reduced. In contrast, heterogeneous integration methods are more widely used. Transferring gallium oxide materials to some substrates with high thermal conductivity can effectively improve heat dissipation efficiency, but its process is relatively complex. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the prior art to at least a certain extent. To this end, one object of the present invention is to provide a high thermal conductivity gallium oxide composite substrate and its preparation method and application.

[0005] In a first aspect of the present invention, a method for preparing a high thermal conductivity gallium oxide composite substrate is provided, the method comprising: (1) Epitaxial growth of gallium oxide single crystal thin films on sapphire substrates; (2) growing a sacrificial MgO layer on the gallium oxide single crystal thin film; (3) growing a gallium oxide single crystal on the MgO sacrificial layer to obtain a gallium oxide wafer; (4) transferring the gallium oxide wafer to a high thermal conductivity substrate by wafer bonding; (5) After wet etching the MgO sacrificial layer, the side of the gallium oxide wafer that contacts the MgO sacrificial layer is polished to obtain a high thermal conductivity gallium oxide composite substrate.

[0006] According to the method for preparing a high thermal conductivity gallium oxide composite substrate provided by the present invention, a gallium oxide single crystal thin film is first epitaxially grown on a sapphire substrate. An MgO sacrificial layer can be further grown on the epitaxially grown gallium oxide single crystal thin film, and then a gallium oxide single crystal can be grown on the MgO sacrificial layer to obtain a gallium oxide wafer. The gallium oxide wafer is then transferred to a high thermal conductivity substrate by wafer bonding. Finally, the MgO sacrificial layer is wet-etched to remove the MgO sacrificial layer. The side of the gallium oxide wafer that contacts the MgO sacrificial layer is then polished to form a gallium oxide wafer on the high thermal conductivity substrate to obtain a high thermal conductivity gallium oxide composite substrate. The present invention provides an MgO sacrificial layer and then removes the MgO sacrificial layer by wet etching, thereby successfully transferring the gallium oxide material to a substrate with a high thermal conductivity coefficient, effectively improving heat dissipation efficiency. This method first forms the MgO sacrificial layer and then wet etches it. The process adopted is simple, has low equipment requirements, high production efficiency, and significantly reduces production costs. At the same time, high-quality gallium oxide single crystal thin films can be epitaxially obtained on the MgO sacrificial layer, and the half-peak width of its Omega rocking curve can reach less than 1000 arc seconds, thereby significantly improving the quality of the gallium oxide wafer.

[0007] In some embodiments of the present invention, in step (1), the thickness of the gallium oxide single crystal thin film is 10 nm-10 μm.

[0008] In some embodiments of the present invention, the surface roughness of the gallium oxide single crystal thin film is less than 20 nm.

[0009] In some embodiments of the present invention, in step (1), the sapphire substrate is selected from a c-plane sapphire substrate.

[0010] In some embodiments of the present invention, the epitaxial growth method of the gallium oxide single crystal thin film includes hydride vapor phase epitaxy, metal organic compound vapor deposition or mist chemical vapor deposition.

[0011] In some embodiments of the present invention, in step (2), the thickness of the MgO sacrificial layer is 10 nm-10 μm.

[0012] In some embodiments of the present invention, the growth method of the MgO sacrificial layer includes hydride vapor phase epitaxy, metal organic compound vapor deposition, pulsed laser deposition or magnetron sputtering.

[0013] In some embodiments of the present invention, in step (3), the thickness of the gallium oxide wafer is 10 nm-10 mm.

[0014] In some embodiments of the present invention, the surface roughness of the gallium oxide wafer is less than 20 nm.

[0015] In some embodiments of the present invention, in step (4), the thickness of the high thermal conductivity substrate is 10 μm-1 cm.

[0016] In some embodiments of the present invention, the high thermal conductivity substrate is selected from silicon carbide, diamond, Cu:diamond alloy ceramic material, silicon or aluminum nitride ceramic.

[0017] In some embodiments of the present invention, the wafer bonding method is selected from metal bonding or dielectric layer bonding.

[0018] In some embodiments of the present invention, the doping type of the gallium oxide single crystal includes unintentional doping, p-type doping, n-type low doping, n-type high doping, or alternating n-type low doping and high doping.

[0019] In some embodiments of the present invention, in step (5), the wet etching is performed using an etchant selected from a phosphoric acid solution, hydrofluoric acid, or a mixed solution of hydrofluoric acid and nitric acid.

[0020] In a second aspect, the present invention provides a high-thermal-conductivity gallium oxide composite substrate prepared using the aforementioned method. The high-thermal-conductivity gallium oxide composite substrate provided by the present invention can be used as a substrate for gallium oxide-based power devices, potentially significantly improving the device's heat dissipation performance.

[0021] In a third aspect of the present invention, the present invention proposes the use of the above-mentioned high thermal conductivity gallium oxide composite substrate in electronic devices.

[0022] In a fourth aspect of the present invention, a vertical structure Schottky barrier diode is proposed, comprising an ohmic contact layer, the above-mentioned high thermal conductivity gallium oxide composite substrate, a SiO2 layer and a Schottky contact layer stacked in sequence, wherein the high thermal conductivity gallium oxide composite substrate is composed of a high thermal conductivity substrate, a bonding layer and a gallium oxide wafer stacked in sequence, the ohmic contact layer contacts the high thermal conductivity substrate, the gallium oxide wafer is convex, the SiO2 layer is located at both ends of the convexity of the gallium oxide wafer and is located in the same plane as the convex part of the gallium oxide wafer, and the Schottky contact layer contacts the gallium oxide wafer.

[0023] The present invention has at least the following beneficial effects: (1) The present invention successfully transfers gallium oxide material to a substrate with high thermal conductivity by setting an MgO sacrificial layer and then removing the MgO sacrificial layer by wet etching, thereby effectively improving heat dissipation efficiency. This method first forms an MgO sacrificial layer and then wet etches it. The process adopted is simple, the equipment requirements are low, the production efficiency is high, and the sapphire substrate can be reused, reducing costs. At the same time, high-quality gallium oxide single crystal thin films can be epitaxially obtained on the MgO sacrificial layer, and the half-peak width of its Omega rocking curve can reach within 1000 arc seconds, thereby significantly improving the quality of gallium oxide wafers.

[0024] (2) The present invention uses wafer bonding technology to heterogeneously integrate gallium oxide single crystals onto a high thermal conductivity substrate, thereby improving the heat dissipation capacity of the device, reducing the impact of temperature on electron drift, and allowing the heat generated by the gallium oxide device to be promptly discharged, thereby reducing the temperature of the device itself and improving the pressure resistance, reliability and working stability of the gallium oxide device.

[0025] (3) The high thermal conductivity gallium oxide composite substrate provided by the present invention can be used to prepare high-performance gallium oxide-based power electronic devices, such as vertical structure SBD devices, effectively improving the heat dissipation problem of gallium oxide power devices and making the device performance more reliable and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are 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.

[0027] Figure 1 This is a structural demonstration diagram of the preparation process of the high thermal conductivity gallium oxide composite substrate of the present invention; Figure 2 This is a schematic structural diagram of a high thermal conductivity gallium oxide composite substrate according to an embodiment of the present invention; Figure 3 1 is a schematic structural diagram of a vertical Schottky barrier diode according to an embodiment of the present invention; Figure 4 It is a schematic diagram of the structural changes during the preparation process of a vertical structure Schottky barrier diode according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0029] In a first aspect of the present invention, a method for preparing a high thermal conductivity gallium oxide composite substrate is provided, the method comprising: (1) Epitaxial growth of gallium oxide single crystal thin films on sapphire substrates; (2) growing a sacrificial MgO layer on the gallium oxide single crystal thin film; (3) growing a gallium oxide single crystal on the MgO sacrificial layer to obtain a gallium oxide wafer; (4) transferring the gallium oxide wafer to a high thermal conductivity substrate by wafer bonding; (5) After wet etching the MgO sacrificial layer, the side of the gallium oxide wafer that contacts the MgO sacrificial layer is polished to obtain a high thermal conductivity gallium oxide composite substrate.

[0030] According to the method for preparing a high thermal conductivity gallium oxide composite substrate provided by the present invention, a gallium oxide single crystal thin film is first epitaxially grown on a sapphire substrate. An MgO sacrificial layer can be further grown on the epitaxially grown gallium oxide single crystal thin film, and then a gallium oxide single crystal can be grown on the MgO sacrificial layer to obtain a gallium oxide wafer. The gallium oxide wafer is then transferred to a high thermal conductivity substrate by wafer bonding. Finally, the MgO sacrificial layer is wet-etched to remove the MgO sacrificial layer. The side of the gallium oxide wafer that contacts the MgO sacrificial layer is then polished to form a gallium oxide wafer on the high thermal conductivity substrate to obtain a high thermal conductivity gallium oxide composite substrate. The present invention provides an MgO sacrificial layer and then removes the MgO sacrificial layer by wet etching, thereby successfully transferring the gallium oxide material to a substrate with a high thermal conductivity coefficient, effectively improving heat dissipation efficiency. This method first forms the MgO sacrificial layer and then wet etches it. The process adopted is simple, has low equipment requirements, high production efficiency, and significantly reduces production costs. At the same time, high-quality gallium oxide single crystal thin films can be epitaxially obtained on the MgO sacrificial layer, and the half-peak width of the Omega rocking curve can reach less than 1000 arc seconds, thereby significantly improving the quality of the gallium oxide wafer.

[0031] Specifically, please refer to Figure 1 A gallium oxide single crystal thin film 2 is epitaxially grown on a sapphire substrate 1, an MgO sacrificial layer 3 is grown on the gallium oxide single crystal thin film 2, and a gallium oxide single crystal is grown on the MgO sacrificial layer 3, thereby obtaining a gallium oxide wafer 6. Furthermore, the gallium oxide wafer 6 includes a stacked low-doped gallium oxide epitaxial layer 4 and a highly-doped gallium oxide epitaxial layer 5, with the low-doped gallium oxide epitaxial layer 4 contacting the MgO sacrificial layer 3.

[0032] According to an embodiment of the present invention, in step (1), the thickness of the gallium oxide single crystal thin film is 10 nm-10 μm.

[0033] According to an embodiment of the present invention, in step (1), the surface roughness of the gallium oxide single crystal thin film is less than 20 nm. It should be noted that the surface roughness mentioned in the present invention refers to the unevenness of the machined surface with small spacing and tiny peaks and valleys, which is usually evaluated by the average arithmetic deviation Ra of the surface profile, which represents the arithmetic mean of the distances from each point on the profile to the reference line.

[0034] According to an embodiment of the present invention, in step (1), the sapphire substrate is selected from a c-plane sapphire substrate.

[0035] According to an embodiment of the present invention, in step (1), the method of epitaxially growing the gallium oxide single crystal thin film on the sapphire substrate includes hydride vapor phase epitaxy, metal organic compound vapor deposition or mist chemical vapor deposition.

[0036] According to an embodiment of the present invention, in step (2), the thickness of the MgO sacrificial layer is 10 nm-10 μm.

[0037] According to an embodiment of the present invention, in step (2), the growth method of the MgO sacrificial layer includes hydride vapor phase epitaxy, metal organic compound vapor phase deposition, pulsed laser deposition or magnetron sputtering.

[0038] According to an embodiment of the present invention, in step (3), the thickness of the gallium oxide wafer is 10 nm-10 mm.

[0039] According to an embodiment of the present invention, in step (3), the growth method of growing the gallium oxide single crystal on the MgO sacrificial layer includes hydride vapor phase epitaxy, metal organic compound vapor phase deposition, and pulsed laser deposition.

[0040] According to an embodiment of the present invention, in step (3), the surface roughness of the gallium oxide wafer is less than 20 nm.

[0041] In some embodiments of the present invention, the gallium oxide wafer is composed of a stack of a low-doped gallium oxide epitaxial layer and a high-doped gallium oxide epitaxial layer, and the low-doped gallium oxide epitaxial layer contacts a MgO sacrificial layer.

[0042] According to an embodiment of the present invention, in step (4), the thickness of the high thermal conductivity substrate is 10 μm-1 cm.

[0043] According to an embodiment of the present invention, the highly thermally conductive substrate is selected from silicon carbide, diamond, Cu:diamond alloy ceramic material, silicon, or aluminum nitride ceramic. A Cu / diamond composite material is preferred. Using a Cu:diamond alloy ceramic material as a transfer substrate acts as a heat sink for external circuits, improving the device's heat dissipation capabilities, reducing the impact of temperature on electron drift, and enabling the timely removal of heat generated by the gallium oxide device, thereby reducing the device's temperature and improving the device's voltage resistance, reliability, and operational stability.

[0044] According to an embodiment of the present invention, the wafer bonding method is selected from metal bonding or dielectric layer bonding.

[0045] Furthermore, the metal bonding material system includes Au-Au, Au-Sn, Au-In, Au-W, Au-Mo and combinations thereof, and also includes Ti-Au, Ti-Sn, Ti-In, Ti-W, Ti-Mo, Ti-Al, Ti-Ag and combinations thereof. The dielectric layer bonding material system includes SiO2, SiNx , TiO x , SOG, Al2O3, SU-8, UV glue, PMMA, resin and other materials.

[0046] According to an embodiment of the present invention, the doping type of the gallium oxide single crystal includes unintentional doping, p-type doping, n-type low doping, n-type high doping, or alternating n-type low doping and high doping.

[0047] According to an embodiment of the present invention, in step (5), the etchant used in the wet etching is selected from phosphoric acid solution, hydrofluoric acid or a mixed solution of hydrofluoric acid and nitric acid.

[0048] Specifically, the sapphire substrate on which the MgO sacrificial layer and the gallium oxide wafer were grown obtained in step (4) is immersed in an etchant. The etching rate can be controlled by controlling the etching temperature and the concentration of the etchant until the sacrificial layer is completely etched away, completing the stripping of the gallium oxide single crystal film.

[0049] According to an embodiment of the present invention, in step (5), after wet etching, the side of the gallium oxide wafer that contacts the MgO sacrificial layer is polished. The specific polishing process is to use CMP chemical mechanical polishing to make the surface roughness Ra of the gallium oxide wafer reach below 0.3 nm, which is convenient for subsequent device preparation.

[0050] In a second aspect, the present invention provides a high-thermal-conductivity gallium oxide composite substrate prepared using the aforementioned method. The high-thermal-conductivity gallium oxide composite substrate provided by the present invention can be used as a substrate for gallium oxide-based power devices, potentially significantly improving the device's heat dissipation performance.

[0051] In some embodiments of the present invention, reference Figure 2 The high thermal conductivity gallium oxide composite substrate includes a high thermal conductivity substrate 8, a bonding layer 7, and a gallium oxide wafer 6 stacked in sequence. Furthermore, the gallium oxide wafer 6 includes a stacked low-doped gallium oxide epitaxial layer 4 and a highly-doped gallium oxide epitaxial layer 5, and the highly-doped gallium oxide epitaxial layer 5 contacts the bonding layer 7.

[0052] In a third aspect of the present invention, the present invention proposes the use of the above-mentioned high thermal conductivity gallium oxide composite substrate in electronic devices.

[0053] In a fourth aspect of the present invention, a vertical Schottky barrier diode is provided. Figure 3It includes an ohmic contact layer 10, the above-mentioned high thermal conductivity gallium oxide composite substrate 20, a SiO2 layer 30 and a Schottky contact layer 40 stacked in sequence. The high thermal conductivity gallium oxide composite substrate 20 is composed of a high thermal conductivity substrate 8, a bonding layer 7 and a gallium oxide wafer 6 stacked in sequence. The ohmic contact layer 10 contacts the high thermal conductivity substrate 8. The gallium oxide wafer 6 is convex. The SiO2 layer 30 is located at both ends of the convex portion of the gallium oxide wafer 6 and is located in the same plane as the convex portion of the gallium oxide wafer 6. The Schottky contact layer 40 contacts the gallium oxide wafer 6.

[0054] In some embodiments of the present invention, the Schottky contact layer 40 is composed of a stack of a Ni layer and an Au layer, and the Ni layer contacts the gallium oxide wafer 6 .

[0055] In some embodiments of the present invention, the ohmic contact layer 10 is composed of a stack of a Ti layer and an Au layer. The Ti layer contacts the high thermal conductivity gallium oxide composite substrate 20 and forms an ohmic contact with the high thermal conductivity gallium oxide composite substrate 20 .

[0056] In some embodiments of the present invention, reference may be made to Figure 4 The preparation method of the vertical structure Schottky barrier diode includes: (1) cleaning the high thermal conductivity gallium oxide composite substrate 20; (2) performing photolithography on the gallium oxide wafer 6 of the high thermal conductivity gallium oxide composite substrate 20 to make the gallium oxide wafer 6 convex, and depositing SiO2 layers 30 on both ends of the convex gallium oxide wafer 6; (3) depositing a Ni metal layer and an Au metal layer on the gallium oxide wafer 6 in sequence, and performing rapid thermal annealing to form a Schottky contact between the metal and the low-doped gallium oxide epitaxial layer; (4) depositing a Ti metal layer and an Au metal layer on the back side of the high thermal conductivity substrate 8 in sequence, and performing rapid thermal annealing to form an ohmic contact layer 10 to form a good ohmic contact.

[0057] In some embodiments of the present invention, the Schottky contact and ohmic contact layers are fabricated using one or more processes such as metal thermal evaporation, magnetron sputtering, and electron beam evaporation. Furthermore, rapid thermal annealing is used to establish ohmic contact between the ohmic contact layer 10 and the high thermal conductivity substrate 8, with the annealing temperature being 400°C to 500°C. Rapid thermal annealing is used to establish Schottky contact between the Schottky contact layer 40 and the gallium oxide single crystal epitaxial layer 2, with the annealing temperature being 400°C to 500°C.

[0058] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0059] Example 1 This embodiment provides a high thermal conductivity gallium oxide composite substrate, the specific preparation process of which is as follows: (1) A gallium oxide single crystal film was epitaxially grown on a c-plane sapphire substrate. The thickness of the gallium oxide single crystal film was 1 μm, and the surface roughness of the gallium oxide single crystal film was 5 nm. (2) growing a MgO sacrificial layer on the gallium oxide single crystal thin film grown in step (1) by metal organic compound vapor deposition, wherein the thickness of the MgO sacrificial layer is 2 μm; (3) growing a gallium oxide single crystal on the above-mentioned MgO sacrificial layer by a pulsed laser deposition method to obtain a gallium oxide wafer, the thickness of the gallium oxide wafer being 5 μm and the surface roughness of the gallium oxide wafer being 5 nm; (4) Transferring the gallium oxide wafer obtained in step (3) together with the sapphire substrate to a Cu: diamond alloy ceramic substrate using a metal wafer bonding method, wherein the thickness of the substrate is 500 μm; (5) The MgO sacrificial layer is wet-etched with a 75% phosphoric acid solution at a temperature of 100°C. After the MgO sacrificial layer is completely etched, the side of the gallium oxide wafer in contact with the MgO sacrificial layer is polished by CMP chemical mechanical polishing. The surface roughness Ra of the gallium oxide wafer reaches below 0.3 nm, thereby obtaining a high thermal conductivity gallium oxide composite substrate.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. 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 high thermal conductivity gallium oxide composite substrate, characterized in that: include: (1) Epitaxial growth of gallium oxide single crystal thin films on sapphire substrates; (2) growing a sacrificial MgO layer on the gallium oxide single crystal thin film; (3) growing a gallium oxide single crystal on the MgO sacrificial layer to obtain a gallium oxide wafer; (4) transferring the gallium oxide wafer to a high thermal conductivity substrate by wafer bonding; (5) After wet etching the MgO sacrificial layer, the side of the gallium oxide wafer that contacts the MgO sacrificial layer is polished to obtain a high thermal conductivity gallium oxide composite substrate.

2. The method according to claim 1, characterized in that In step (1), the thickness of the gallium oxide single crystal film is 10 nm-10 μm; And / or, the surface roughness of the gallium oxide single crystal thin film is less than 20 nm.

3. The method according to claim 1 or 2, characterized in that In step (1), the sapphire substrate is selected from a c-plane sapphire substrate; And / or, the epitaxial growth method of the gallium oxide single crystal thin film includes hydride vapor phase epitaxy, metal organic compound vapor deposition or mist chemical vapor deposition.

4. The method according to claim 1 or 2, characterized in that In step (2), the thickness of the MgO sacrificial layer is 10 nm-10 μm; And / or, the growth method of the MgO sacrificial layer includes hydride vapor phase epitaxy, metal organic compound vapor deposition, pulsed laser deposition or magnetron sputtering.

5. The method according to claim 1 or 2, characterized in that: In step (3), the thickness of the gallium oxide wafer is 10 nm-10 mm; And / or, the surface roughness of the gallium oxide wafer is less than 20 nm.

6. The method according to claim 1 or 2, characterized in that: In step (4), the thickness of the high thermal conductivity substrate is 10 μm-1 cm; and / or, the high thermal conductivity substrate is selected from silicon carbide, diamond, Cu:diamond alloy ceramic material, silicon or aluminum nitride ceramic; And / or, the wafer bonding method is selected from metal bonding or dielectric layer bonding; And / or, the doping type of the gallium oxide single crystal includes unintentional doping, p-type doping, n-type low doping, n-type high doping, or alternating n-type low doping and high doping.

7. The method according to claim 1 or 2, characterized in that: In step (5), the wet etching adopts an etchant selected from phosphoric acid solution, hydrofluoric acid or a mixed solution of hydrofluoric acid and nitric acid.

8. A high thermal conductivity gallium oxide composite substrate, characterized in that: The method according to any one of claims 1 to 7 is used to prepare the present invention.

9. Use of the high thermal conductivity gallium oxide composite substrate according to claim 8 in electronic devices.

10. A vertical Schottky barrier diode, characterized in that: It comprises an ohmic contact layer, the high thermal conductivity gallium oxide composite substrate according to claim 8, a SiO2 layer and a Schottky contact layer stacked in sequence, wherein the high thermal conductivity gallium oxide composite substrate is composed of a high thermal conductivity substrate, a bonding layer and a gallium oxide wafer stacked in sequence, the ohmic contact layer contacts the high thermal conductivity substrate, the gallium oxide wafer is convex, the SiO2 layer is located at both ends of the convexity of the gallium oxide wafer and is located in the same plane as the convex part of the gallium oxide wafer, and the Schottky contact layer contacts the gallium oxide wafer.

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