A gallium oxide-based boron-doped diamond semiconductor composite coating material, a preparation method therefor, and applications thereof

Abstract

The application discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material and a preparation method and application thereof. The gallium oxide-based boron-doped diamond semiconductor composite coating material comprises, from bottom to top, a gallium oxide base, a gradient boron-doped Ga2O3 semiconductor transition layer arranged on the surface of the gallium oxide base, a boron-doped SiO2 buffer layer arranged on the surface of the gradient boron-doped Ga2O3 semiconductor transition layer, and a gradient boron-doped diamond semiconductor layer arranged on the surface of the boron-doped SiO2 buffer layer. The boron content of the gradient boron-doped Ga2O3 semiconductor transition layer increases from bottom to top. The boron content of the gradient boron-doped diamond semiconductor layer decreases from bottom to top. The semiconductor composite coating material prepared by the application has good electrical properties, film-substrate bonding properties and high stability.

Description

Technical Field

[0001] This invention relates to a gallium oxide-based boron-doped diamond semiconductor composite coating material, its preparation method, and its application, belonging to the field of materials preparation. Background Technology

[0002] Diamond possesses excellent physicochemical properties. Its hardness, molar density, thermal conductivity, sound velocity, and elastic modulus are the highest among known materials. It also exhibits good corrosion resistance, light transmittance, heat resistance, and radiation resistance. Pure diamond has a very high resistivity, making it an excellent electrical insulator. Doping diamond with boron atoms transforms it from an insulator with a bandgap of 5.47 eV into a semiconductor or even a conductor, greatly expanding its application range. At low doping levels, diamond exhibits semiconductor properties, with high electron / hole mobility, making it an ideal material for fabricating high-temperature semiconductors and radiation-resistant semiconductors. At high doping levels, diamond exhibits semi-metallic conductivity, making it an ideal anolyte material for electrochemical synthesis, electrochemical oxidation, and electrochemical analysis. Using chemical vapor deposition (CVD) technology, boron-doped diamond (BDD) coatings can be deposited on various substrates within a reasonable timescale and controllable doping range.

[0003] Gallium oxide (Ga2O3) is a transparent, direct bandgap semiconductor material with a bandgap of 4.9 eV. It boasts a high breakdown field strength of 8 MW / cm, good thermal and chemical stability, making it suitable for various applications in high-frequency, high-power devices, ultraviolet detectors, gas sensors, and other semiconductor devices. It has the potential to surpass current power device technologies based on GaN and SiC. However, its extremely low thermal conductivity (0.14 W / cm·K) leads to severe self-heating during operation, affecting device performance and lifespan.

[0004] Directly growing CVD diamond coatings on Ga2O3 substrates can effectively improve the self-heating effect of large-area Ga2O3 semiconductor devices and enhance device stability. However, during CVD diamond deposition, direct exposure of the Ga2O3 substrate to H2 plasma can lead to surface damage or even disintegration; the significant difference in lattice constant and thermal expansion coefficient also makes it difficult for diamond to bond with Ga2O3. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the first objective of the present invention is to provide a gallium oxide-based boron-doped diamond semiconductor composite coating material with both high bonding strength and high stability.

[0006] The second objective of this invention is to provide a method for preparing a highly binding gallium oxide-based boron-doped diamond semiconductor composite coating material.

[0007] The third objective of this invention is to provide an application of a gallium oxide-based boron-doped diamond semiconductor composite coating material.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material. The gallium oxide-based boron-doped diamond semiconductor composite coating material comprises, from bottom to top, a gallium oxide substrate, a gradient boron-doped Ga2O3 semiconductor transition layer disposed on the surface of the gallium oxide substrate, a boron-doped SiO2 buffer layer disposed on the surface of the gradient boron-doped Ga2O3 semiconductor transition layer, and a gradient boron-doped diamond semiconductor layer disposed on the surface of the boron-doped SiO2 buffer layer. The boron content in the gradient boron-doped Ga2O3 semiconductor transition layer increases from bottom to top; the boron content in the gradient boron-doped diamond semiconductor layer decreases from bottom to top.

[0010] In this invention, the small radius and high BO bond energy of boron ions make boron ion implantation into Ga2O3 semiconductors less likely to form B2O3 oxides, facilitating direct doping of boron ions into the Ga2O3 lattice. Simultaneously, it helps to further improve the chemical bonding between the Ga2O3 substrate and the BDD coating, reducing interfacial thermal resistance and enhancing the service stability of the BDD composite coating material. The low boron content in the bottom layer of the transition layer prevents damage to the gallium oxide crystal structure from high-energy impurity ion bombardment, helping to preserve the good electrical properties of the gallium oxide substrate. The maximum boron ion concentration is near the surface of the transition layer, which helps to enhance the chemical bonding between the transition layer and the BDD coating, improving the service life of the composite coating material. The SiO2 buffer layer significantly improves the surface stability of the Ga2O3 substrate, preventing the Ga2O3 from being etched by H2 plasma during CVD deposition. It also effectively reduces the mismatch in thermal expansion coefficients between diamond and the Ga2O3 substrate, reducing the residual stress of the boron-doped diamond coating and improving the film-substrate bonding performance. The interfacial thermal resistance of the composite material mainly originates from the SiO2 buffer layer, and the interfacial bonding strength is a key factor affecting the interfacial thermal resistance. Boron doping of the SiO2 buffer layer can further improve the chemical bonding between the SiO2 buffer layer and the gradient boron-doped diamond semiconductor layer and the gradient boron-doped Ga2O3 semiconductor transition layer, effectively reducing the interfacial thermal resistance and improving the service stability of the material.

[0011] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material. The thickness of the gradient boron-doped Ga₂O₃ semiconductor transition layer is 200–500 nm. The boron ions in the gradient boron-doped Ga₂O₃ semiconductor transition layer exhibit an approximately Gaussian distribution, with the peak position of the Gaussian-distributed boron ions at a depth of 25–150 nm and a peak boron ion concentration of 10⁻⁶. 18 ~1020 cm -3 .

[0012] In this invention, the transition layer thickness represents the maximum ion implantation depth. Because ion implantation is a non-equilibrium process, high-energy atoms undergo cascade collisions with the atomic nucleus and its extranuclear electrons, forming a concentration peak of the implanted element on the material surface within a depth range, with an approximate Gaussian distribution. In this invention, the peak concentration of B ions is controlled within 10... 18 ~10 20 cm -3 Within the specified range, the resulting gradient boron-doped Ga2O3 semiconductor transition layer exhibits the best performance. If the boron ion concentration is too high, the formation of boron compounds will compete with boron doping, leading to a decrease in material performance; if the boron ion concentration is too low, the doping effect is not significant.

[0013] In this invention, the B ions have a relatively small mass, resulting in a larger number of B ions being backscattered during ion implantation. Consequently, the number of ions distributed near the peak and on one side of the surface is greater than on the other side of the peak. The average implanted ion depth (the depth of the peak position of the Gaussian distribution) is 50–100 nm, and the maximum B ion concentration is near the surface, which helps to enhance the chemical bonding between the transition layer and the BDD coating, reduce the interfacial thermal resistance, and further improve the material's service performance.

[0014] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material, wherein the thickness of the boron-doped SiO2 buffer layer is 100–300 nm, and the boron doping concentration on the surface of the boron-doped SiO2 buffer layer is 10. 18 ~10 20 cm -3 .

[0015] In this invention, the thicker the boron-doped SiO2 buffer layer, the thicker the gradient boron-doped diamond coating grown on it, and the larger the grain size. However, SiO2 has lower thermal conductivity than diamond, and an excessively thick buffer layer will increase the interfacial thermal resistance between the gradient boron-doped diamond semiconductor layer / boron-doped SiO2 buffer layer and the boron-doped SiO2 buffer layer / gradient boron-doped Ga2O3 semiconductor transition layer, which will have an adverse effect on the overall thermal conductivity of the composite material.

[0016] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material. The gradient boron-doped diamond layer, from bottom to top, comprises a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer. The boron-doped diamond bottom layer has a uniform boron content, with a B / C ratio of 46,666-60,000 ppm (atomic ratio). The boron content in the boron-doped diamond intermediate layer decreases linearly from bottom to top, with the boron content at the bottom layer being the maximum and decreasing linearly to the top layer.

[0017] In this invention, the boron-doped diamond bottom layer uses a uniform boron content to maximize the conductivity of the coating, enhance the chemical bonding between the BDD coating and the gradient boron-doped Ga2O3 transition layer, and further improve the film-substrate bonding performance. The boron-doped diamond top layer also uses a uniform boron content to maximize the thermal conductivity of the top layer, effectively reduce the coating peeling rate, and improve the service life of the composite coating material. The boron-doped diamond intermediate layer adopts a linearly decreasing boron gradient, which allows for a natural transition between coatings, making it less prone to separation and breakage, and improving the bonding strength.

[0018] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material, wherein the gradient boron-doped diamond semiconductor layer is uniformly deposited on the surface of a boron-doped SiO2 buffer layer by chemical vapor deposition, and the thickness of the gradient boron-doped diamond semiconductor layer is 1μm-2mm.

[0019] The process involves first depositing a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and finally depositing a boron-doped diamond top layer on the substrate surface.

[0020] In this invention, the boron-doped diamond bottom layer, the boron-doped diamond middle layer, and the boron-doped diamond top layer all have the same thickness range.

[0021] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material, wherein the gallium oxide is selected from amorphous, polycrystalline, and single crystal; and the polycrystalline or single crystal crystal is selected from α-Ga2O3, β-Ga2O3, ε-Ga2O3, δ-Ga2O3, and γ-Ga2O3.

[0022] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material, wherein the gallium oxide substrate is Ga-rich gallium oxide.

[0023] Gallium-rich gallium oxide refers to gallium oxide with gallium as the main chemical component and low oxygen content. The inventors discovered that when the matrix is ​​in Ga-rich mode, B ions can bind to Ga sites better, which is more conducive to the incorporation of B.

[0024] This invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material, wherein the structure of the gallium oxide substrate is one of zero-dimensional, one-dimensional, two-dimensional, or three-dimensional.

[0025] The present invention discloses a gallium oxide-based boron-doped diamond semiconductor composite coating material, wherein the gallium oxide substrate has a micro-nano structure on its surface.

[0026] In this invention, the fabrication method of the micro-nano structure is not limited, such as at least one of high-temperature atmosphere etching, high-temperature metal etching, and plasma etching.

[0027] This invention discloses a method for preparing a gallium oxide-based boron-doped diamond semiconductor composite coating material. The method involves ion implantation of boron (B) onto a gallium oxide substrate, followed by a first annealing treatment to obtain a gradient boron-doped Ga2O3 semiconductor transition layer. A boron-doped SiO2 buffer layer is then prepared on the surface of the gradient boron-doped Ga2O3 semiconductor transition layer via plasma-enhanced chemical vapor deposition (PECVD). A second annealing treatment is then performed. Finally, the gallium oxide substrate with the boron-doped SiO2 buffer layer is subjected to chemical vapor deposition to obtain the gallium oxide-based boron-doped diamond semiconductor composite coating material.

[0028] In a preferred embodiment, when implanting boron (B) onto the surface of a gallium oxide substrate, the boron ion dose is controlled to be 2–20 × 10⁻⁶. 15 cm -2 The ion injection energy is 10–50 keV.

[0029] In a further preferred embodiment, when the ion implantation energy is 10–25 keV, the ion beam current density is 0.5–1.5 μA / cm². 2 When the implanted ion energy is 26–50 keV, the ion beam current density is 2–3 μA / cm. 2 .

[0030] In this invention, when the ion implantation energy is low, a lower ion beam current density is used, which can effectively control the ion implantation rate and prevent high-energy ion aggregation from causing lattice damage; when the ion implantation energy is high, a higher ion beam current density is used, which helps to improve the ion diffusion concentration and diffusion rate.

[0031] More preferably, the ion implantation energy is 10–25 keV, and the ion beam current density is 0.5–1.5 μA / cm². 2 The ion dose is 5–10 × 10⁻⁶. 15 cm -2 When the transition layer is at its optimal performance, the resulting layer exhibits the best performance.

[0032] In this invention, the transition layer exhibits optimal performance when using a lower ion implantation energy and a higher ion dose. If the ion implantation energy exceeds this range, the average ion implantation depth is greater, potentially leading to a lower peak boron ion concentration, which is detrimental to enhancing the chemical bonding between the transition layer and the BDD coating. Conversely, if the ion implantation energy is lower than this range, it may affect the stability of the ion beam. Using a higher ion dose helps increase the peak boron ion concentration, enhances the chemical bonding between the transition layer and the BDD coating, reduces interfacial thermal resistance, and further improves the service life of the composite material. However, excessively high implantation ion doses can cause severe lattice damage.

[0033] In this invention, the gradient boron-doped Ga2O3 semiconductor transition layer undergoes a first annealing treatment. This first annealing repairs lattice damage caused by boron ion implantation, activates impurities, and restores electron and hole mobility.

[0034] In a preferred embodiment, the first annealing treatment is performed under a vacuum or inert atmosphere, wherein the inert atmosphere is selected from nitrogen or argon; the temperature of the first annealing treatment is 600–1000℃, preferably 750–900℃, and the time of the first annealing treatment is 1–30 min.

[0035] In this invention, the transition layer with the first annealing temperature of 750–900°C exhibits the best performance. Below this temperature range, the diffusion process is faster than the annealing process, leading to the outward expansion of boron ions and a decrease in peak concentration. Above this temperature range, significant impurity redistribution occurs, negating the inherent advantages of ion implantation technology. Furthermore, high temperatures easily generate boron compounds, resulting in a decline in material properties.

[0036] In a preferred embodiment, during the process of preparing the boron-doped SiO2 buffer layer by plasma chemical vapor deposition, a mixed atmosphere containing SiH4, N2O, and B2H6 is introduced, with a volumetric flow rate ratio of SiH4:B2H6:N2O = 1:(0.02~0.10):90; the temperature of the plasma chemical vapor deposition is 200~300℃, preferably 220~250℃; the pressure of the plasma chemical vapor deposition is 50~70Pa, the radio frequency power is 6~10W, and the deposition time is 5~30min.

[0037] In a preferred embodiment, the second annealing treatment is carried out in a mixed atmosphere of N2 and O2, the temperature of the second annealing treatment is 400-900℃, and the time of the second annealing treatment is 100-150 min; the volume ratio of N2 to O2 is (1-3):1.

[0038] In this invention, annealing is performed in an O2-containing environment. Due to further oxidation during the annealing process, the pressure stability of the boron-doped SiO2 buffer layer can be improved. However, excessively high O2 concentration will lead to large compressive stress, so it is necessary to dope with an inert gas.

[0039] In a further preferred embodiment, the temperature of the second annealing is not higher than the temperature of the first annealing.

[0040] In a further preferred embodiment, the second annealing time is 135–150 min.

[0041] In this invention, the second annealing time must exceed 135 minutes to achieve the profile of a conventional thermally diffused B sample. If the time is less than this range, insufficient B ion diffusion will result in B ions accumulating at the top of the buffer layer, adversely affecting the overall bonding performance of the composite material. If the annealing time is greater than this range, the diffusion depth of B ions will increase, affecting the distribution of B in the Ga2O3 matrix.

[0042] In this invention, the second annealing treatment can remove residual stress during the growth of the boron-doped SiO2 buffer layer, thereby improving the crystallinity and stability of the material; at the same time, it can activate impurities and repair damage.

[0043] A preferred embodiment of the process for growing a gradient boron-doped diamond semiconductor layer on a gallium oxide substrate with a boron-doped SiO2 buffer layer via chemical vapor deposition is as follows: First, the gallium oxide substrate with the boron-doped SiO2 buffer layer is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a gallium oxide substrate with surface-adsorbed nanocrystalline and / or microcrystalline diamond is obtained. Then, the gallium oxide substrate with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced to perform chemical vapor deposition to grow a gradient boron-doped diamond semiconductor layer. The temperature of the chemical vapor deposition is 600-1000℃, and the gas pressure is 10. 3 -10 4 Pa, time is 3-20h.

[0044] In a further preferred embodiment, the suspension containing nanocrystalline and / or microcrystalline diamond mixed particles has a diamond mixed particle mass fraction of 0.01%-0.05%; the diamond mixed particles have a particle size of 5-30 nm and a purity of ≥97%; and the ultrasonic treatment time is 5-30 min.

[0045] In a further preferred embodiment, during the chemical vapor deposition, the percentage of carbon-containing gas in the total gas mass flow rate in the furnace is 0.5-10.0%, preferably 2-5%.

[0046] In a further preferred embodiment, during the chemical vapor deposition, the percentage of boron-containing gas in the total mass flow rate of the furnace is first controlled to be 0.069%-0.0884% to obtain a boron-doped diamond underlayer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total mass flow rate of the furnace is 0.03968%-0.0593% to obtain a boron-doped diamond transition layer. Then, the percentage of boron-containing gas in the total mass flow rate of the furnace is controlled to be 0.03968%-0.0593% again to obtain a boron-doped diamond outer layer; thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0047] The present invention also provides an application of gallium oxide-based boron doped diamond semiconductor composite material, wherein the gallium oxide-based boron doped diamond semiconductor composite coating material is applied to at least one of semiconductor devices, power electronics, high-temperature sensors, solar energy devices, and electrochemistry.

[0048] Beneficial effects

[0049] This invention addresses the problems of Ga2O3 substrates being easily etched by H2 plasma under CVD deposition conditions, resulting in poor film-substrate adhesion and high interfacial thermal resistance between the CVD diamond coating and the Ga2O3 substrate. It proposes a method where a gradient boron-doped Ga2O3 semiconductor transition layer is formed on the surface of the gallium oxide substrate, followed by a gradient boron-doped diamond semiconductor layer on the surface of the transition layer. This creates a Ga2O3-gradient boron-doped Ga2O3 semiconductor transition layer-gradient boron-doped diamond semiconductor composite coating material configuration, effectively reducing interfacial thermal resistance and improving the film-substrate adhesion and service performance of the gallium oxide / BDD semiconductor composite coating material. Detailed Implementation

[0050] Example 1

[0051] Boron ion was implanted onto the surface of a gallium oxide substrate, with the boron ion dose controlled at 1.9 × 10⁻⁶. 16 cm -2 The injection energy was 40 keV, and the ion beam current density was 2.5 μA / cm². 2 Then, it was subjected to a first annealing treatment in nitrogen atmosphere at a temperature of 900℃ for 20 minutes. This yielded a gradient boron-doped Ga₂O₃ semiconductor transition layer with a thickness of 200 nm, an average implanted ion depth of 75 nm, and a peak boron ion concentration of 6 × 10⁻⁶. 20 cm -3 At this depth, the ions are approximately Gaussian distributed.

[0052] A boron-doped SiO2 buffer layer was then prepared on the surface of a gradient boron-doped Ga2O3 semiconductor transition layer via plasma-enhanced chemical vapor deposition (PECVD). A mixed atmosphere containing SiH4, N2O, and B2H6 was introduced, with a volumetric flow rate ratio of SiH4:B2H6:N2O = 1:0.06:90. The PECVD temperature was 220℃, the pressure was 50 Pa, the RF power was 8 W, and the deposition time was 20 min. A second annealing treatment was then performed in a mixed atmosphere of N2 and O2, with a volume ratio of N2 to O2 of 2:1. The second annealing temperature was 900℃, and the annealing time was 135 min. The resulting boron-doped SiO2 buffer layer had a thickness of 213 nm and a boron doping concentration of 3 × 10⁻⁶ on its surface. 19 cm -3 .

[0053] Then, a gallium oxide substrate with a boron-doped SiO2 buffer layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with nanocrystalline and / or microcrystalline diamond adsorbed on its surface is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.05%; the particle size of the diamond mixture particles is 10 nm, and the purity is ≥97%; the ultrasonic treatment time is 30 min.

[0054] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced in a linear decreasing manner until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0593% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to obtain a boron-doped diamond top layer. Thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0055] The carbon-containing gas accounts for 3% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 650℃, and the gas pressure is 10. 3 The deposition time was 8 hours. The thickness of the prepared gradient boron-doped diamond semiconductor layer was 5.31 μm, and the average diamond grain size was approximately 600 nm.

[0056] Measurements showed that the average thermal conductivity of the diamond coating on the composite coating material prepared by this invention was 180 W / mK, which is much higher than that of the initial Ga2O3 matrix (14 W / mK), and the interfacial thermal resistance of the composite material was 30 m. 2K / GW.

[0057] Example 2

[0058] Boron ion was implanted onto the surface of a gallium oxide substrate, with the boron ion dose controlled at 4 × 10⁻⁶. 15 cm -2 The injection energy was 15 keV, and the ion beam current density was 1 μA / cm. 2 Then, it was subjected to a first annealing treatment in nitrogen at a temperature of 700℃ for 20 minutes. This yielded a gradient boron-doped Ga₂O₃ semiconductor transition layer with a thickness of 100 nm, an average implanted ion depth of 35 nm, and a peak boron ion concentration of 5 × 10⁻⁶. 19 cm -3 At this depth, the ions are approximately Gaussian distributed.

[0059] A boron-doped SiO2 buffer layer was then prepared on the surface of a gradient boron-doped Ga2O3 semiconductor transition layer via plasma-enhanced chemical vapor deposition (PECVD). A mixed atmosphere containing SiH4, N2O, and B2H6 was introduced, with a volumetric flow rate ratio of SiH4:B2H6:N2O = 1:0.03:90. The PECVD temperature was 220℃, the pressure was 50 Pa, the RF power was 8 W, and the deposition time was 5 min. A second annealing treatment was then performed in a mixed atmosphere of N2 and O2, with a volume ratio of N2 to O2 of 2:1. The second annealing temperature was 600℃, and the annealing time was 90 min. The resulting boron-doped SiO2 buffer layer had a thickness of 96 nm and a boron doping concentration of 5 × 10⁻⁶ on its surface. 18 cm -3 .

[0060] Then, a gallium oxide substrate with a boron-doped SiO2 buffer layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with nanocrystalline and / or microcrystalline diamond adsorbed on its surface is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.05%; the particle size of the diamond mixture particles is 10 nm, and the purity is ≥97%; the ultrasonic treatment time is 30 min.

[0061] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced in a linear decreasing manner until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0593% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to obtain a boron-doped diamond top layer. Thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0062] The carbon-containing gas accounts for 3% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 650℃, and the gas pressure is 10. 3 The deposition time was 8 hours. The thickness of the resulting gradient boron-doped diamond semiconductor layer was 1.76 μm, and the average diamond grain size was approximately 300 nm.

[0063] Measurements showed that the average thermal conductivity of the diamond coating on the composite coating material prepared by this invention was 165 W / mK, which is much higher than that of the initial Ga2O3 matrix (14 W / mK). The interfacial thermal resistance of the composite material was 14 m. 2 K / GW.

[0064] Example 3

[0065] Boron ion was implanted onto the surface of a gallium oxide substrate, with the boron ion dose controlled at 1.3 × 10⁻⁶. 16 cm -2 The injection energy was 15 keV, and the ion beam current density was 1 μA / cm. 2 Then, it was subjected to a first annealing treatment in nitrogen atmosphere at a temperature of 900℃ for 20 minutes. This yielded a gradient boron-doped Ga₂O₃ semiconductor transition layer with a thickness of 120 nm, an average implanted ion depth of 40 nm, and a peak boron ion concentration of 3 × 10⁻⁶. 20 cm -3 At this depth, the ions are approximately Gaussian distributed.

[0066] A boron-doped SiO2 buffer layer was then prepared on the surface of a gradient boron-doped Ga2O3 semiconductor transition layer via plasma-enhanced chemical vapor deposition (PECVD). A mixed atmosphere containing SiH4, N2O, and B2H6 was introduced, with a volumetric flow rate ratio of SiH4:B2H6:N2O = 1:0.06:90. The PECVD temperature was 220℃, the pressure was 50 Pa, the RF power was 8 W, and the deposition time was 20 min. A second annealing treatment was then performed in a mixed atmosphere of N2 and O2, with a volume ratio of N2 to O2 of 2:1. The second annealing temperature was 600℃, and the annealing time was 135 min. The resulting boron-doped SiO2 buffer layer had a thickness of 213 nm and a boron doping concentration of 3 × 10⁻⁶ on its surface. 19 cm -3 .

[0067] Then, a gallium oxide substrate with a boron-doped SiO2 buffer layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with nanocrystalline and / or microcrystalline diamond adsorbed on its surface is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.05%; the particle size of the diamond mixture particles is 10 nm, and the purity is ≥97%; the ultrasonic treatment time is 30 min.

[0068] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced in a linear decreasing manner until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0593% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to obtain a boron-doped diamond top layer. Thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0069] The carbon-containing gas accounts for 3% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 650℃, and the gas pressure is 10. 3 The deposition time was 8 hours. The thickness of the resulting gradient boron-doped diamond semiconductor layer was 7.03 μm, and the average diamond grain size was approximately 650 nm.

[0070] Measurements showed that the average thermal conductivity of the diamond coating on the composite coating material prepared by this invention was 203 W / mK, which is much higher than that of the initial Ga2O3 matrix (14 W / mK), and the interfacial thermal resistance of the composite material was 25 m. 2K / GW.

[0071] Comparative Example 1

[0072] All other conditions were the same as in Example 1, except that no boron-doped SiO2 buffer layer was prepared before the deposition of the gradient boron-doped diamond semiconductor layer. As a result, no diamond coating grew on the surface of the composite material, the surface of the Ga2O3 substrate was etched by H atoms, and there were obvious Ga spheres on the substrate surface.

[0073] Comparative Example 2

[0074] All other conditions were the same as in Example 1, except that no boron source was incorporated during the preparation of the SiO2 buffer layer. The average thermal conductivity of the diamond coating on the resulting composite material was 159 W / mK, and the interfacial thermal resistance of the composite material was 65 mΩ. 2 K / GW, the performance is far inferior to that of Example 1.

[0075] Comparative Example 3

[0076] All other conditions were the same as in Example 1, except that the deposition time of the boron-doped SiO2 buffer layer was 60 min, and the thickness of the resulting boron-doped SiO2 buffer layer was 500 nm. The average thermal conductivity of the diamond coating on the resulting composite coating material was 140 W / mK, and the interfacial thermal resistance of the composite material was 79 mΩ. 2 K / GW, the performance is far inferior to that of Example 1.

[0077] Comparative Example 4

[0078] All other conditions were the same as in Example 1, except that the ion dose was 1.9 × 10⁻⁶ when preparing the gradient boron-doped Ga₂O₃ transition layer. 17 cm -2 The resulting transition layer thickness was 290 nm, the average depth of implanted ions was 112 nm, and the peak concentration of boron ions was 5 × 10⁻⁶. 18 cm -3 The formation of BO compounds competes with BO doping, leading to a decrease in doping concentration. The average thermal conductivity of the diamond coating on the resulting composite material is 154 W / mK, and the interfacial thermal resistance of the composite material is 50 mΩ. 2 K / GW, the performance is far inferior to that of Example 1.

[0079] Comparative Example 5

[0080] All other conditions were the same as in Example 1, except that the first annealing temperature was 580°C, the thickness of the resulting transition layer was 420 nm, the average depth of implanted ions was 170 nm, and the peak concentration of boron ions was 3 × 10⁻⁶. 17 cm -3Boolean ion diffusion leads to a decrease in doping concentration. The average thermal conductivity of the diamond coating on the resulting composite material is 127 W / mK, and the interfacial thermal resistance of the composite material is 80 mΩ. 2 K / GW, the performance is far inferior to that of Example 1.

Claims

1. A gallium oxide-based boron-doped diamond semiconductor composite coating material, characterized in that: The gallium oxide-based boron-doped diamond semiconductor composite coating material consists of, from bottom to top, a gallium oxide substrate, a gradient boron-doped Ga2O3 semiconductor transition layer disposed on the surface of the gallium oxide substrate, a boron-doped SiO2 buffer layer disposed on the surface of the gradient boron-doped Ga2O3 semiconductor transition layer, and a gradient boron-doped diamond semiconductor layer disposed on the surface of the boron-doped SiO2 buffer layer. The boron content in the gradient boron-doped Ga2O3 semiconductor transition layer increases from bottom to top, while the boron content in the gradient boron-doped diamond semiconductor layer decreases from bottom to top.

2. The gallium oxide-based boron-doped diamond semiconductor composite coating material according to claim 1, characterized in that: The thickness of the gradient boron-doped Ga2O3 semiconductor transition layer is 200-500 nm, and the peak concentration of boron ions is 10. 18 ~10 20 cm -3 .

3. The gallium oxide-based boron-doped diamond semiconductor composite coating material according to claim 1 or 2, characterized in that: The thickness of the boron-doped SiO2 buffer layer is 100~300 nm, and the boron doping concentration on the surface of the boron-doped SiO2 buffer layer is 10%. 18 ~10 20 cm -3 .

4. A gallium oxide-based boron-doped diamond semiconductor composite coating material according to claim 1 or 2, characterized in that: The gradient boron-doped diamond semiconductor layer comprises, from bottom to top, a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer. The boron-doped diamond bottom layer has a uniform boron content, with a B / C ratio of 46,666-60,000 ppm (atomic ratio). The boron-doped diamond top layer also has a uniform boron content, with a B / C ratio of 26,666-40,000 ppm (atomic ratio). The boron content in the boron-doped diamond intermediate layer decreases linearly from bottom to top, with the boron content at the bottom layer being the maximum and decreasing linearly to the boron content at the top layer.

5. A gallium oxide-based boron-doped diamond semiconductor composite coating material according to claim 1 or 2, characterized in that: The gallium oxide matrix is ​​selected from amorphous, polycrystalline, and single crystal; the polycrystalline or single crystal crystal form is one of α-Ga2O3, β-Ga2O3, ε-Ga2O3, δ-Ga2O3, and γ-Ga2O3. The gallium oxide substrate is Ga-rich gallium oxide; The structure of the gallium oxide substrate is one-dimensional, two-dimensional, or three-dimensional. The gallium oxide substrate has a micro / nano structure on its surface.

6. A method for preparing a gallium oxide-based boron-doped diamond semiconductor composite coating material according to any one of claims 1-5, characterized in that: A gradient boron-doped Ga2O3 semiconductor transition layer is obtained by ion implantation of boron onto the surface of a gallium oxide substrate, followed by a first annealing treatment. A boron-doped SiO2 buffer layer is then prepared on the surface of the gradient boron-doped Ga2O3 semiconductor transition layer by plasma chemical vapor deposition, followed by a second annealing treatment. Finally, a gradient boron-doped diamond semiconductor layer is grown on the gallium oxide substrate with the boron-doped SiO2 buffer layer by chemical vapor deposition, thus obtaining a gallium oxide-based boron-doped diamond semiconductor composite coating material.

7. The method for preparing a gallium oxide-based boron-doped diamond semiconductor composite coating material according to claim 6, characterized in that: When boron is implanted onto a gallium oxide substrate, the boron ion dose is controlled to be 2–20 × 10⁻⁶. 15 cm -2 The ion injection energy is 10~50keV; The first annealing treatment is carried out under a vacuum or inert atmosphere, wherein the inert atmosphere is selected from nitrogen or argon; the temperature of the first annealing treatment is 600~1000℃, and the time of the first annealing treatment is 1~30min.

8. The method for preparing a gallium oxide-based boron-doped diamond semiconductor composite coating material according to claim 6, characterized in that: During the process of preparing the boron-doped SiO2 buffer layer by plasma chemical vapor deposition, a mixed atmosphere containing SiH4, N2O and B2H6 is introduced, with a volumetric flow rate ratio of SiH4:B2H6:N2O = 1:0.02~0.10:90; the plasma chemical vapor deposition temperature is 200~300℃, the plasma chemical vapor deposition pressure is 50~70Pa, the radio frequency power is 6~10W, and the deposition time is 5~30min. The second annealing treatment is carried out in a mixed atmosphere of N2 and O2, the temperature of the second annealing treatment is 400~900℃, and the time of the second annealing treatment is 100~150min; the volume ratio of N2 to O2 is 1~3:

1.

9. The method for preparing a gallium oxide-based boron-doped diamond semiconductor composite coating material according to claim 6, characterized in that: The process of growing a gradient boron-doped diamond semiconductor layer on a gallium oxide substrate with a boron-doped SiO2 buffer layer via chemical vapor deposition is as follows: First, the gallium oxide substrate with the boron-doped SiO2 buffer layer is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a gallium oxide substrate with surface-adsorbed nanocrystalline and / or microcrystalline diamond is obtained. Then, the gallium oxide substrate with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced to perform chemical vapor deposition to grow a gradient boron-doped diamond semiconductor layer. The temperature of the chemical vapor deposition is 600-1000℃, and the gas pressure is 10. 3 -10 4 Pa, time is 3-20h; In the suspension containing nanocrystalline and / or microcrystalline diamond mixed particles, the mass fraction of diamond mixed particles is 0.01%-0.05%; the particle size of the diamond mixed particles is 5-30 nm, and the purity is ≥97%; the ultrasonic treatment time is 5-30 min. During the chemical vapor deposition process, the percentage of carbon-containing gas in the total gas mass flow rate within the furnace is 0.5-10.0%. During the chemical vapor deposition process, the percentage of boron-containing gas in the total mass flow rate of the furnace is first controlled to be 0.069%-0.0884% to obtain a boron-doped diamond underlayer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total mass flow rate of the furnace is 0.03968%-0.0593% to obtain a boron-doped diamond transition layer. Then, the percentage of boron-containing gas in the total mass flow rate of the furnace is controlled to be 0.03968%-0.0593% again to obtain a boron-doped diamond outer layer; thus, a gradient boron-doped diamond semiconductor layer is obtained.

10. The application of the gallium oxide-based boron-doped diamond semiconductor composite coating material according to any one of claims 1-5, characterized in that: The gallium oxide-based boron-doped diamond semiconductor composite coating material is applied to at least one of semiconductor devices, power electronics, high-temperature sensors, solar energy devices, and electrochemistry.