Nitrogen and metal co-doped p-type gallium oxide thin film and preparation method thereof

Abstract

The invention provides a preparation method of an N and metal co-doped p-type gallium oxide film, and belongs to the technical field of semiconductor materials. The N-doped gallium oxide thin film is obtained by annealing an unintentionally doped silicon-based GaN epitaxial wafer in an oxygen atmosphere. A layer of metal is uniformly distributed on the surface of the N-doped gallium oxide thin film, and then the N-doped gallium oxide thin film is placed in an anoxic environment to be annealed to obtain the N and metal co-doped p-type gallium oxide thin film. The method is simple to operate, and the hole concentration of the prepared N and metal co-doped p-type gallium oxide thin film reaches 1 * 10 < 11 > cm <-3 >-1 * 10 < 19 > cm <-3 >.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor materials, and in particular relates to a nitrogen and metal co-doped p-type gallium oxide film and a preparation method thereof. Background Art

[0002] Gallium oxide (Ga2O3) has been reported to have five crystal phases: α-Ga2O3, β-Ga2O3, γ-Ga2O3, ε-Ga2O3 and δ-Ga2O3, and these five crystal phase structures can be transformed into each other under certain conditions. Among them, β-Ga2O3 is the most stable crystal phase. Compared with the other four crystal phases, β-Ga2O3 exhibits excellent physical, optical and electrical properties. Therefore, it is widely used in high-power power electronic devices and solar-blind ultraviolet detection devices. The realization of n-type and p-type doping is crucial in the application of high-power power electronic devices. However, the technology for realizing n-type doping of β-Ga2O3 is relatively mature, but the realization of p-type doping is still highly challenging.

[0003] There are three main reasons why it is difficult to achieve p-type doping in β-Ga2O3: (1) The valence band top (VBM) of β-Ga2O3 is composed of O with small energy dispersion, large effective mass and high state density. 2p The hole mobility in the VBM is low due to the control of the orbit. The holes generated by the p-type metal dopant replacing Ga are easily captured by the O polaron, resulting in the inability of the holes in the VBM to move freely. (2) During the β-Ga2O3 crystal growth and thin film epitaxy process, unintentional doping impurities and intrinsic defects form n-type conductivity through ionization, forming a self-compensation effect on the p-type acceptor impurities, making the p-type dopant unable to play the role of an acceptor impurity. (3) The defect formation energy of the p-type dopant during the doping process is high, resulting in a low effective dopant concentration; and, due to the large band gap of β-Ga2O3 (4.9 eV), the ionization energy of the metal elements (Mg, Fe, Zn, etc.) and N elements that can be doped is large, and they are deep energy level acceptor impurity defects, which are difficult to ionize at room temperature.

[0004] N-doping and N-metal co-doping have been shown to be potential solutions for achieving p-type doping of β-Ga2O3. For example, the Chinese patent application publication CN110350028A discloses a method for preparing a nitrogen-doped P-type gallium oxide film, and the carrier concentration of the obtained P-type gallium oxide film is 1×10 9 ~1×10 17 cm -3. However, this process still has its shortcomings. The impurity energy level of nitrogen is deep, and it will introduce donor impurities, resulting in a decrease in hole mobility. CN111769035A discloses a method for preparing a Zn and N co-doped gallium oxide film, which is prepared by using a metal organic chemical vapor deposition process on a substrate that has been cleaned and pre-treated by corrosion; then, the doping concentration a of Zn is controlled to be 0.031 to 0.125 and the doping concentration b of N is controlled to be 0.021 to 0.083 on the prepared buffer layer, and Zn and N co-doped Ga 1- a Zn a O 1-b N b This method only simulates and calculates the peak value of the state density near the Fermi level of the film, and finds that the distribution of the state density at the top of the valence band expands along the low energy level direction. In theory, the gallium oxide film has a higher hole carrier concentration. The simulated hole carrier concentration of the gallium oxide film is 5×10 9 ~1×10 18 / cm 3 However, this method has no actual case effect, and only proves the feasibility of the process through simulation calculation. Summary of the invention

[0005] Based on the above problems, the present invention provides a p-type gallium oxide film co-doped with N and metal and a preparation method thereof. The method comprises annealing an unintentionally doped silicon-based GaN epitaxial wafer in an oxygen atmosphere, cooling it, laying a metal element, annealing it again and cooling it down, thereby obtaining a p-type gallium oxide film co-doped with N and metal.

[0006] Specifically, the present invention adopts the following technical solutions to achieve the above objectives: A method for preparing a nitrogen and metal co-doped p-type gallium oxide film comprises the following steps: S1. In an oxygen atmosphere, annealing the unintentionally doped silicon-based GaN epitaxial wafer at 900-1100° C. for 30-90 min, and cooling to room temperature after annealing to obtain an N-doped gallium oxide epitaxial layer; S2, a layer of metal is evenly distributed on the surface of the N-doped gallium oxide epitaxial layer obtained in step S1; S3, annealing the epitaxial wafer with metal distributed on the surface in step S2 at 500-1150° C. for 30-60 min in an oxygen-deficient environment, and cooling to room temperature after annealing to obtain a p-type gallium oxide thin film co-doped with N and metal.

[0007] In a preferred embodiment, the gas providing the oxygen atmosphere in step S1 is at least one of N2O, O2, and NO.

[0008] In a preferred embodiment, step S1 includes the step of pretreating the unintentionally doped silicon-based GaN epitaxial wafer: the unintentionally doped silicon-based GaN epitaxial wafer is immersed in acetone, anhydrous ethanol, and deionized water respectively for ultrasonic treatment, taken out and rinsed with running deionized water, and then blown dry with dry nitrogen.

[0009] In a preferred embodiment, the heating rate of heating to the annealing temperature in step S1 is 12-16° C. / min.

[0010] In a preferred embodiment, the cooling rate from step S1 to room temperature is 12 to 16°C / min.

[0011] In a preferred embodiment, the flow rate of the gas providing the oxygen atmosphere in step S1 is 2000-5000 sccm.

[0012] In a preferred solution, the method of uniformly distributing a layer of metal on the surface of the N-doped gallium oxide epitaxial layer in step S2 is direct placement or spin coating.

[0013] In a preferred embodiment, the gas providing the oxygen-deficient environment in step S3 is an inert gas.

[0014] In a preferred embodiment, the flow rate of the gas providing the oxygen-deficient environment in step S3 is 5000-10000 sccm.

[0015] In a preferred embodiment, the heating rate of heating to the annealing temperature in step S3 is 7-11° C. / min.

[0016] In a preferred embodiment, the cooling rate to room temperature in step S3 is 12-16°C / min.

[0017] The present invention also provides a N- and metal-co-doped p-type gallium oxide film prepared according to any one of the above schemes.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The method for preparing a nitrogen and metal co-doped p-type gallium oxide thin film of the present invention is simple and convenient, and the main reaction process only requires two annealing steps to obtain a p-type gallium oxide thin film.

[0019] (2) In the present invention, the valence band structure of the gallium oxide film is first regulated by N-doping, so that the top of the valence band is closer to the intrinsic Fermi level of gallium oxide; then, metal is laid (evenly distributed) on the surface of the N-doped gallium oxide film, so that the metal diffuses into the interior of the gallium oxide film under high-temperature annealing to achieve N+ metal co-doping, which can reduce the defect formation energy and ionization energy of a single P-type dopant and increase the effective doping concentration.

[0020] (3) By co-doping with N+ metal, the peak value of the state density near the Fermi level of the gallium oxide film is increased, making the acceptor energy level closer to the top of the valence band, overcoming the problem that the single P-type dopant is farther away from the top of the valence band, and increasing the hole concentration in the gallium oxide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The process flow chart of preparing N- and metal-co-doped p-type gallium oxide thin film in the present invention; Figure 2 The SEM and EDS-Mapping images of the N and Mg co-doped p-type gallium oxide thin film prepared in Example 1 of the present invention; Figure 3 The Hall curve of the N and Mg co-doped p-type gallium oxide film prepared in Example 1 of the present invention; Figure 4 This is a diagram showing the calculation results of the Hall test of the N and Mg co-doped p-type gallium oxide film prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] The following content is combined with the embodiments to clearly and completely describe the technical solution of the present application so that those skilled in the art can fully understand the present application. Obviously, the described embodiments are only some preferred embodiments of the present application, rather than all embodiments. Any equivalent transformation or substitution made to the following implementation modes by those of ordinary skill in the art without creative work belongs to the protection scope of the present application.

[0023] The methods not described in detail in the following embodiments are all conventional methods well known to those skilled in the art.

[0024] A specific embodiment of the present invention provides a method for preparing a p-type gallium oxide thin film co-doped with N and metal, comprising the following steps: S1. In an oxygen atmosphere, the unintentionally doped silicon-based GaN epitaxial wafer is subjected to high temperature annealing to prepare N-doped gallium oxide thin films (β-Ga2N x O 3-x , 0.01<x<0.5), regulating the valence band top of the gallium oxide film; The specific steps are as follows: S1-1, take an unintentionally doped silicon-based GaN epitaxial wafer, soak it in acetone, anhydrous ethanol, and deionized water for 15 minutes respectively, take it out, rinse it with running deionized water, and blow it dry with dry nitrogen; S1-2, fix the unintentionally doped silicon-based GaN epitaxial wafer pretreated in step S1-1 in an annealing furnace with the GaN surface facing downward, start a mechanical pump to evacuate the vacuum annealing furnace to a vacuum degree of ≤10Pa; introduce 2000-5000sccm of oxidizing gas to raise the pressure in the annealing furnace to normal pressure, and then evacuate again to ≤10Pa, repeat the above steps of increasing the pressure with oxidizing gas and evacuating again 3 times, and finally make the vacuum degree inside the annealing furnace ≤10Pa; S1-3, set the annealing furnace temperature to 900℃~1100℃, the heating rate to 12~16℃ / min, and the flow rate of the oxidizing gas to 2000~5000sccm; when the temperature in the annealing furnace reaches 900℃~1100℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 30~90min to transform the GaN film into an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5); S1-4, after the annealing is completed, the temperature of the annealing furnace is set to 20°C~30°C, the cooling rate is set to 12~16°C / min, the flow rate of the oxidizing gas is set to 2000~5000sccm, and the cooling program is started to obtain an N-doped gallium oxide thin film layer; S2, evenly laying a layer of metal on the surface of the N-doped gallium oxide thin film layer obtained in step S1; S3, performing high temperature annealing treatment on the epitaxial wafer with metal on the surface in step S2 in an oxygen-deficient environment to obtain a N- and metal-co-doped gallium oxide film (β-M y Ga 2-y N x O 3-x , 0.01<x<0.5, 0.01<y<0.5, M represents metal); The specific operations are as follows: S3-1, fix the epitaxial wafer with metal on the surface in step S2 in an annealing furnace, start the mechanical pump to evacuate the annealing furnace to make the vacuum degree ≤10Pa; introduce 5000-10000sccm of inert gas to raise the pressure in the annealing furnace to normal pressure, then evacuate again to ≤10Pa, repeat the above steps of increasing the pressure with inert gas and evacuating again 3 times, and finally make the vacuum degree inside the annealing furnace ≤10Pa; S3-2, setting the annealing furnace temperature to 500°C~1150°C, the heating rate to 7~11°C / min, and the flow rate of the inert gas to 5000~10000sccm; when the temperature reaches 500°C~1150°C, ensuring that the inside of the annealing furnace is at normal pressure, and continuing annealing for 30~60min to allow the metal to fully diffuse into the inside of the N-doped gallium oxide film, so that the N-doped gallium oxide film is transformed into a gallium oxide film co-doped with N and metal; S3-3. After the annealing is completed, the annealing furnace temperature is set to 20°C~30°C, the cooling rate is set to 12~16°C / min, the flow rate of the inert gas is set to 5000~10000sccm, and the cooling program is started to obtain a N and metal co-doped gallium oxide thin film layer with a thickness of 1~10nm.

[0025] As an example, the oxygen atmosphere in step S1 is provided by at least one of the oxidizing gases N2O, O2, and NO.

[0026] As an example, the size of the unintentionally doped silicon-based GaN epitaxial wafer in step S1-1 is 10mm×10mm, 15mm×15mm, 20mm×20mm, 25mm×25mm (1 inch), 51mm×51mm (2 inches), 3 inches, 4 inches, 5 inches or 6 inches.

[0027] As an example, the flow rate of the oxidizing gas in step S1-2 is 2000 sccm, 2100 sccm, 2500 sccm, 2800 sccm, 3000 sccm, 3500 sccm, 3800 sccm, 4000 sccm, 4500 sccm, and 5000 sccm.

[0028] As an example, the annealing temperature in step S1-3 is 900°C, 920°C, 950°C, 980°C, 1000°C, 1050°C, 1080°C, and 1100°C.

[0029] As an example, the heating rates in step S1-3 are 12°C / min, 13°C / min, 14°C / min, 15°C / min, and 16°C / min.

[0030] As an example, the flow rate of the oxidizing gas in step S1-3 is 2000 sccm, 2050 sccm, 2200 sccm, 2600 sccm, 3000 sccm, 3300 sccm, 3700 sccm, 4000 sccm, 4500 sccm, and 5000 sccm.

[0031] As an example, the annealing time in step S1-3 is 30 min, 32 min, 35 min, 38 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, and 90 min.

[0032] As an example, the temperature of the annealing furnace in step S1-4 is set to 20°C, 22°C, 25°C, 28°C, and 30°C.

[0033] As an example, the cooling rates in step S1-4 are 12°C / min, 13°C / min, 14°C / min, 15°C / min, and 16°C / min.

[0034] As an example, the flow rate of the oxidizing gas in step S1-4 is 2000 sccm, 2100 sccm, 2200 sccm, 2400 sccm, 3000 sccm, 3200 sccm, 3300 sccm, 4000 sccm, 4200 sccm, 4800 sccm, and 5000 sccm.

[0035] As an example, the method of laying the metal in step S2 is to evenly lay the metal directly on the surface of the N-doped gallium oxide thin film layer or to heat the solid metal to a molten state and then spin-coat it on the surface of the N-doped gallium oxide thin film layer.

[0036] As an example, the metal in step S2 is any one of Mg, Zn, and Cu.

[0037] As an example, the flow rate of the inert gas in step S3-1 is 5000sccm, 5100sccm, 5200sccm, 5400sccm, 5500sccm, 6000sccm, 6500sccm, 7000sccm, 7500sccm, 8000sccm, 8500sccm, 9000sccm, and 10000sccm.

[0038] As an example, the annealing temperature in step S3-2 is 500°C, 600°C, 650°C, 700°C, 750°C, 800°C, 1080°C, 1100°C, or 1150°C.

[0039] As an example, the heating rates in step S3-2 are 7°C / min, 8°C / min, 9°C / min, 10°C / min, and 11°C / min.

[0040] As an example, the flow rate of the inert gas in step S3-2 is 5000sccm, 5100sccm, 5200sccm, 5400sccm, 5500sccm, 6000sccm, 6500sccm, 6800sccm, 7000sccm, 7500sccm, 8000sccm, 8500sccm, 9000sccm, 9500sccm, and 10000sccm.

[0041] As an example, the annealing time in step S3-2 is 30 min, 35 min, 37 min, 40 min, 45 min, 50 min, 55 min, and 60 min.

[0042] As an example, the temperature of the annealing furnace in step S3-3 is set to 20°C, 22°C, 25°C, 28°C, and 30°C.

[0043] As an example, the cooling rates in step S1-4 are 12°C / min, 13°C / min, 14°C / min, 15°C / min, and 16°C / min.

[0044] As an example, the flow rate of the inert gas in step S3-3 is 5000sccm, 5100sccm, 5200sccm, 5400sccm, 5500sccm, 6000sccm, 6500sccm, 6800sccm, 7000sccm, 7500sccm, 8000sccm, 8500sccm, 9000sccm, 9500sccm, and 10000sccm.

[0045] As an example, the oxygen-deficient environment in step S3 is provided by at least one of the inert gases N2, He, Ne, Ar, Kr, and Xe.

[0046] Example 1 Reference Figure 1 , a method for preparing a N and Mg co-doped p-type gallium oxide film, comprising the following steps: S1. In an oxygen atmosphere, a 10 mm × 10 mm unintentionally doped silicon-based GaN epitaxial wafer was subjected to high temperature annealing to prepare an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5), regulating the valence band top of the gallium oxide film.

[0047] The specific steps are as follows: S1-1. Take a 10 mm×10 mm non-intentionally doped silicon-based GaN epitaxial wafer, and ultrasonically immerse it in acetone, anhydrous ethanol, and deionized water for 15 minutes respectively. After taking it out, rinse it with running deionized water and blow it dry with dry nitrogen.

[0048] S1-2, fix the unintentionally doped silicon-based GaN epitaxial wafer pretreated in step S1-1 in an annealing furnace, with the GaN side facing downward, and start the mechanical pump to evacuate the vacuum annealing furnace to a vacuum degree of less than 5 Pa. Pass 5000 sccm of N2O to increase the pressure in the annealing furnace from 5 Pa to normal pressure, and then evacuate it again to 5 Pa, repeat the above steps of increasing the pressure with N2O and evacuating again for 3 times, and finally make the vacuum degree inside the annealing furnace less than 5 Pa.

[0049] S1-3, set the annealing furnace temperature to (1000±5)℃, the heating rate to 14℃ / min, and the N2O flow rate to 5000sccm. When the temperature in the annealing furnace reaches (1000±5)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 60 minutes to transform the GaN film into an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5).

[0050] S1-4. After the annealing is completed, the temperature of the annealing furnace is set to 25°C, the cooling rate is set to 14°C / min, the N2O flow rate is set to 5000sccm, and the cooling program is started to obtain an N-doped gallium oxide thin film layer with a thickness of 5 μm.

[0051] S2. 3 mg of metal magnesium is evenly placed on the surface of the N-doped gallium oxide thin film layer obtained in step S1.

[0052] S3, performing high temperature annealing treatment on the epitaxial wafer with metal magnesium placed on the surface in step S2 in an oxygen-deficient environment to obtain a N and Mg co-doped gallium oxide film (β-Mg y Ga 2-y N x O 3-x , 0.01<x<0.5, 0.01<y<0.5).

[0053] The specific operations are as follows: S3-1, fix the epitaxial wafer with magnesium metal placed on the surface in step S2 in an annealing furnace, start the mechanical pump to evacuate the annealing furnace to a vacuum degree of less than 5 Pa. Pass 5000 sccm of N2 to increase the pressure in the annealing furnace from 5 Pa to normal pressure, then evacuate to 5 Pa again, repeat the above steps of increasing the pressure with N2 and evacuating again 3 times, and finally make the vacuum degree inside the annealing furnace less than 5 Pa.

[0054] S3-2, set the annealing furnace temperature to (700±3)℃, the heating rate to 9℃ / min, and the N2 flow rate to 5000sccm. When the temperature reaches (700±3)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 60min to allow the metal Mg to fully diffuse into the inside of the N-doped gallium oxide film, so that the N-doped gallium oxide film is transformed into a gallium oxide film co-doped with N and Mg.

[0055] S3-3. After the annealing is completed, the annealing furnace temperature is set to 25°C, the cooling rate is set to 13°C / min, the N2 flow rate is set to 5000sccm, and the cooling program is started to obtain a N and Mg co-doped gallium oxide thin film layer with a thickness of 6nm.

[0056] Example 2 Reference Figure 1 , a method for preparing a N and Mg co-doped p-type gallium oxide film, comprising the following steps: S1. In an oxygen atmosphere, a 20 mm × 20 mm unintentionally doped silicon-based GaN epitaxial wafer was subjected to high temperature annealing to prepare an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5), regulating the valence band top of the gallium oxide film.

[0057] The specific steps are as follows: S1-1. Take a 20 mm×20 mm non-intentionally doped silicon-based GaN epitaxial wafer, and ultrasonically immerse it in acetone, anhydrous ethanol, and deionized water for 15 minutes respectively. After taking it out, rinse it with running deionized water and blow it dry with dry nitrogen.

[0058] S1-2, fix the unintentionally doped silicon-based GaN epitaxial wafer pretreated in step S1-1 in an annealing furnace, with the GaN side facing downward, and start the mechanical pump to evacuate the vacuum annealing furnace to a vacuum degree of less than 10 Pa. Pass 2000 sccm of O2 to increase the pressure in the annealing furnace from 10 Pa to normal pressure, and then evacuate it again to 10 Pa, repeat the above steps of increasing the pressure with O2 and evacuating again for 3 times, and finally make the vacuum degree inside the annealing furnace less than 10 Pa.

[0059] S1-3, set the annealing furnace temperature to (900±5)℃, the heating rate to 12℃ / min, and the O2 flow rate to 2000sccm. When the temperature in the annealing furnace reaches (900±5)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 30 minutes to transform the GaN film into an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5).

[0060] S1-4. After the annealing is completed, the temperature of the annealing furnace is set to 25°C, the cooling rate is set to 12°C / min, the O2 flow rate is set to 2000sccm, and the cooling program is started to obtain an N-doped gallium oxide thin film layer with a thickness of 5 μm.

[0061] S2. Place 2 mg of magnesium metal in a sapphire crucible, and then place it in an annealing furnace, and heat it in a nitrogen atmosphere at normal pressure to transform the solid magnesium metal into a molten state (the temperature range is generally 550°C-750°C). Spin-coat 1 mg of molten magnesium metal evenly on the surface of the N-doped gallium oxide thin film layer obtained in step S1.

[0062] S3, performing high temperature annealing treatment on the epitaxial wafer with metal magnesium placed on the surface in step S2 in an oxygen-deficient environment to obtain a N and Mg co-doped gallium oxide film (β-Mg y Ga 2-y N x O 3-x , 0.01<x<0.5, 0.01<y<0.5).

[0063] The specific operations are as follows: S3-1, fix the epitaxial wafer with magnesium metal placed on the surface in step S2 in an annealing furnace, start the mechanical pump to evacuate the annealing furnace to a vacuum degree of less than 5 Pa. Pass 5000 sccm of Ar to increase the pressure in the annealing furnace from 5 Pa to normal pressure, then evacuate to 5 Pa again, repeat the above steps of increasing the pressure with Ar and evacuating again 3 times, and finally make the vacuum degree inside the annealing furnace less than 5 Pa.

[0064] S3-2, set the annealing furnace temperature to (500±3)℃, the heating rate to 7℃ / min, and the Ar flow rate to 5000sccm. When the temperature reaches (500±3)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 60min to allow the metal Mg to fully diffuse into the inside of the N-doped gallium oxide film, so that the N-doped gallium oxide film is transformed into a gallium oxide film co-doped with N and Mg.

[0065] S3-3. After the annealing is completed, the annealing furnace temperature is set to 25°C, the cooling rate is set to 12°C / min, the Ar flow rate is set to 5000sccm, and the cooling program is started to obtain a N and Mg co-doped gallium oxide thin film layer with a thickness of 1 nm.

[0066] Example 3 Reference Figure 1 , a method for preparing a N and Mg co-doped p-type gallium oxide film, comprising the following steps: S1. In an oxygen atmosphere, a 2-inch unintentionally doped silicon-based GaN epitaxial wafer was subjected to high temperature annealing to prepare an N-doped gallium oxide film (β-Ga2N x O3-x , 0.01<x<0.5), regulating the valence band top of the gallium oxide film.

[0067] The specific steps are as follows: S1-1. Take a 2-inch unintentionally doped silicon-based GaN epitaxial wafer, and ultrasonically immerse it in acetone, anhydrous ethanol, and deionized water for 15 minutes respectively. After taking it out, rinse it with running deionized water and blow it dry with dry nitrogen.

[0068] S1-2, fix the unintentionally doped silicon-based GaN epitaxial wafer pretreated in step S1-1 in an annealing furnace, with the GaN side facing downward, and start the mechanical pump to evacuate the vacuum annealing furnace to a vacuum degree of less than 5 Pa. Introduce 5000 sccm of NO to raise the pressure in the annealing furnace from 5 Pa to normal pressure, and then evacuate it again to 5 Pa, repeat the above steps of increasing the pressure with NO and evacuating again for 3 times, and finally make the vacuum degree inside the annealing furnace less than 5 Pa.

[0069] S1-3, set the annealing furnace temperature to (1100±5)℃, the heating rate to 16℃ / min, and the NO flow rate to 5000sccm. When the temperature in the annealing furnace reaches (1100±5)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 90 minutes to transform the GaN film into an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5).

[0070] S1-4. After the annealing is completed, the temperature of the annealing furnace is set to 25°C, the cooling rate is set to 16°C / min, the NO flow rate is set to 5000 sccm, and the cooling program is started to obtain an N-doped gallium oxide thin film layer with a thickness of 5 μm.

[0071] S2, 8 mg of magnesium metal is placed in a sapphire crucible, and then placed in an annealing furnace, and heated under nitrogen atmosphere to convert solid magnesium metal into a molten state. 5 mg of molten magnesium metal is evenly spin-coated on the surface of the N-doped gallium oxide thin film layer obtained in step S1.

[0072] S3, performing high temperature annealing treatment on the epitaxial wafer with metal magnesium placed on the surface in step S2 in an oxygen-deficient environment to obtain a N and Mg co-doped gallium oxide film (β-Mg y Ga 2-y N x O 3-x , 0.01<x<0.5, 0.01<y<0.5).

[0073] The specific operations are as follows: S3-1, fix the epitaxial wafer with magnesium metal placed on the surface in step S2 in an annealing furnace, start the mechanical pump to evacuate the annealing furnace to a vacuum degree of less than 5 Pa. Pass 6500sccm of N2 to increase the pressure in the annealing furnace from 5Pa to normal pressure, then evacuate to 5Pa again, repeat the above steps of increasing the pressure with N2 and evacuating again 3 times, and finally make the vacuum degree inside the annealing furnace less than 5Pa.

[0074] S3-2, set the annealing furnace temperature to (800±5)℃, the heating rate to 11℃ / min, and the N2 flow rate to 6500sccm. When the temperature reaches (800±5)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 30 minutes to allow the metal Mg to fully diffuse into the inside of the N-doped gallium oxide film, so that the N-doped gallium oxide film is transformed into a gallium oxide film co-doped with N and Mg.

[0075] S3-3. After the annealing is completed, the annealing furnace temperature is set to 25°C, the cooling rate is set to 16°C / min, the N2 flow rate is set to 6500sccm, and the cooling program is started to obtain a N and Mg co-doped gallium oxide thin film layer with a thickness of 10nm.

[0076] Example 4 Reference Figure 1 , a method for preparing a N and Zn co-doped p-type gallium oxide thin film, comprising the following steps: S1. In an oxygen atmosphere, a 4-inch unintentionally doped silicon-based GaN epitaxial wafer was subjected to high temperature annealing to prepare an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5), regulating the valence band top of the gallium oxide film.

[0077] The specific steps are as follows: S1-1. Take a 4-inch unintentionally doped silicon-based GaN epitaxial wafer, and soak it in acetone, anhydrous ethanol, and deionized water for 15 minutes respectively by ultrasonic. After taking it out, rinse it with running deionized water and blow it dry with dry nitrogen.

[0078] S1-2, fix the unintentionally doped silicon-based GaN epitaxial wafer pretreated in step S1-1 in an annealing furnace, with the GaN side facing downward, and start the mechanical pump to evacuate the vacuum annealing furnace to a vacuum degree of less than 8 Pa. Pass 3000 sccm of O2 to increase the pressure in the annealing furnace from 8 Pa to normal pressure, and then evacuate it again to 8 Pa, repeat the above steps of increasing the pressure with O2 and evacuating again for 3 times, and finally make the vacuum degree inside the annealing furnace less than 8 Pa.

[0079] S1-3, set the annealing furnace temperature to (950±5)℃, the heating rate to 13℃ / min, and the O2 flow rate to 3000sccm. When the temperature in the annealing furnace reaches (950±5)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 45 minutes to transform the GaN film into an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5).

[0080] S1-4. After the annealing is completed, the temperature of the annealing furnace is set to 25°C, the cooling rate is set to 15°C / min, the O2 flow rate is set to 3000sccm, and the cooling program is started to obtain an N-doped gallium oxide thin film layer with a thickness of 5 μm.

[0081] S2. 2 mg of metal zinc is evenly placed on the surface of the N-doped gallium oxide thin film layer obtained in step S1.

[0082] S3, performing high temperature annealing treatment on the epitaxial wafer with metal zinc placed on the surface in step S2 in an oxygen-deficient environment to obtain a N and Zn co-doped gallium oxide film (β-Mg y Ga 2-y N x O 3-x , 0.01<x<0.5, 0.01<y<0.5).

[0083] The specific operations are as follows: S3-1, fix the epitaxial wafer with metal zinc placed on the surface in step S2 in an annealing furnace, start the mechanical pump to evacuate the annealing furnace to a vacuum degree of less than 8 Pa. Pass 10000 sccm of N2 to increase the pressure in the annealing furnace from 8 Pa to normal pressure, then evacuate to 8 Pa again, repeat the above steps of increasing the pressure with N2 and evacuating again 3 times, and finally make the vacuum degree inside the annealing furnace less than 8 Pa.

[0084] S3-2, set the annealing furnace temperature to (500±3)℃, the heating rate to 8℃ / min, and the N2 flow rate to 10000sccm. When the temperature reaches (500±3)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 60min to allow the metal Zn to fully diffuse into the inside of the N-doped gallium oxide film, so that the N-doped gallium oxide film is transformed into a gallium oxide film co-doped with N and Zn.

[0085] S3-3. After the annealing is completed, the annealing furnace temperature is set to 25°C, the cooling rate is set to 14°C / min, the N2 flow rate is set to 10000sccm, and the cooling program is started to obtain a N and Zn co-doped gallium oxide thin film layer with a thickness of 4nm.

[0086] Example 5 Reference Figure 1 , a method for preparing a N and Cu co-doped p-type gallium oxide film, comprising the following steps: S1. In an oxygen atmosphere, a 6-inch unintentionally doped silicon-based GaN epitaxial wafer was subjected to high temperature annealing to prepare an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5), regulating the valence band top of the gallium oxide film.

[0087] The specific steps are as follows: S1-1. Take a 6-inch unintentionally doped silicon-based GaN epitaxial wafer, and soak it in acetone, anhydrous ethanol, and deionized water for 15 minutes respectively by ultrasonic. After taking it out, rinse it with running deionized water and blow it dry with dry nitrogen.

[0088] S1-2, fix the unintentionally doped silicon-based GaN epitaxial wafer pretreated in step S1-1 in an annealing furnace, with the GaN side facing downward, and start the mechanical pump to evacuate the vacuum annealing furnace to a vacuum degree of less than 5 Pa. Pass 5000 sccm of N2O to increase the pressure in the annealing furnace from 5 Pa to normal pressure, and then evacuate it again to 5 Pa, repeat the above steps of increasing the pressure with N2O and evacuating again for 3 times, and finally make the vacuum degree inside the annealing furnace less than 5 Pa.

[0089] S1-3, set the annealing furnace temperature to (1050±5)℃, the heating rate to 15℃ / min, and the N2O flow rate to 5000sccm. When the temperature in the annealing furnace reaches (1050±5)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 55 minutes to transform the GaN film into an N-doped gallium oxide film (β-Ga2N x O 3-x , 0.01<x<0.5).

[0090] S1-4. After the annealing is completed, the temperature of the annealing furnace is set to 25°C, the cooling rate is set to 13°C / min, the N2O flow rate is set to 5000sccm, and the cooling program is started to obtain an N-doped gallium oxide thin film layer with a thickness of 5 μm.

[0091] S2. 4 mg of copper foil is laid on the surface of the N-doped gallium oxide thin film layer obtained in step S1.

[0092] S3, the epitaxial wafer with the copper metal placed on the surface in step S2 is subjected to high temperature annealing treatment in an oxygen-deficient environment to obtain a N and Cu co-doped gallium oxide film (β-Mg y Ga 2-y N x O 3-x , 0.01<x<0.5, 0.01<y<0.5).

[0093] The specific operations are as follows: S3-1, fix the epitaxial wafer with metal copper placed on the surface in step S2 in an annealing furnace, start the mechanical pump to evacuate the annealing furnace to a vacuum degree of less than 5 Pa. Pass 5000 sccm of N2 to increase the pressure in the annealing furnace from 5 Pa to normal pressure, then evacuate to 5 Pa again, repeat the above steps of increasing the pressure with N2 and evacuating again 3 times, and finally make the vacuum degree inside the annealing furnace less than 5 Pa.

[0094] S3-2, set the annealing furnace temperature to (1150±5)℃, the heating rate to 10℃ / min, and the N2 flow rate to 5000sccm. When the temperature reaches (1150±5)℃, ensure that the inside of the annealing furnace is at normal pressure, and continue annealing for 60min to allow the metal Cu to fully diffuse into the inside of the N-doped gallium oxide film, so that the N-doped gallium oxide film is transformed into a gallium oxide film co-doped with N and Cu.

[0095] S3-3. After the annealing is completed, the annealing furnace temperature is set to 25°C, the cooling rate is set to 15°C / min, the N2 flow rate is set to 5000sccm, and the cooling program is started to obtain a N and Cu co-doped gallium oxide thin film layer with a thickness of 8nm.

[0096] p-type gallium oxide thin film structure analysis and performance testing The N and Mg co-doped p-type gallium oxide film (size 10 mm×10 mm) prepared in Example 1 was subjected to SEM morphology and EDS-Mapping surface element composition analysis. The results are as follows: Figure 2 shown. Figure 2 The above (a) figure is a SEM image, (b) figure is a Mg element mapping image, and (c) figure is a N element mapping image. The composition analysis results show that the N content is 1.59wt% and the Mg content is 11.28wt%, indicating that the N and Mg co-doped p-type gallium oxide film was successfully prepared in Example 1.

[0097] Since the hole concentration of N and Mg co-doped p-type gallium oxide film is low at room temperature, the deposition of Ni / Au composite layer on the film surface cannot achieve ohmic contact, resulting in inaccurate Van der Pauw Hall test. Therefore, a magnetron sputtering device was used to deposit 1×10 500nm thick layers on the four corners of the film. 17 ~1×10 19 cm -3 The NiO layer is then subjected to the Van der Pauw Hall test to obtain the hole concentration at room temperature. The Hall test results are shown in Figure 3 shown. Figure 31-2 on the diagram indicates that the first electrode contacts the second electrode, 2-3 indicates that the second electrode contacts the third electrode, 3-4 indicates that the third electrode contacts the fourth electrode, and 4-1 indicates that the fourth electrode contacts the first electrode. Figure 3 It can be seen that the current and voltage between the four electrodes show a linear trend, R 2 Represents the good ohmic contact and the reliability of the test results, R 2 =1 indicates that the gold plate contact surface of the sample has good ohmic contact. After applying the magnetic field, the Hall signal test analysis is performed, and the results are shown in Figure 4 and Table 1.

[0098] Table 1 Hall test results of N and Mg co-doped gallium oxide film prepared in Example 1 at 800K

[0099] It can be seen from Table 1 that the N and Mg co-doped p-type gallium oxide film prepared in Example 1 has good conductivity, and the hole concentration is (4.4~4.7)×10 13 cm -3 The inventor team also found in the experimental process that the hole concentration of the N- and metal-co-doped p-type gallium oxide film prepared by the technical solution of the present application is 1×10 11 cm -3 ~1×10 19 cm -3 Fluctuates within the range.

[0100] The above-described embodiments are only preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. For any person skilled in the art, the present application may have various changes and modifications. Any simple equivalent changes and modifications made based on the scope of protection of the present application and the contents of the specification should be included in the scope of protection of the present application.

Claims

1. A method for preparing a nitrogen and metal co-doped p-type gallium oxide thin film, characterized in that: The following steps are involved: S1. In an oxygen atmosphere, annealing the unintentionally doped silicon-based GaN epitaxial wafer at 900-1100°C for 30-90 minutes, and cooling to room temperature after annealing to obtain an N-doped gallium oxide epitaxial layer; S2, a layer of metal is evenly distributed on the surface of the N-doped gallium oxide epitaxial layer obtained in step S1; S3, annealing the epitaxial wafer with metal distributed on the surface in step S2 at 500-1150° C. for 30-60 min in an oxygen-deficient environment, and cooling to room temperature after annealing to obtain a p-type gallium oxide thin film co-doped with N and metal.

2. The preparation method according to claim 1, characterized in that: The gas providing the oxygen atmosphere in step S1 is at least one of N2O, O2, and NO; or / and the gas providing the oxygen-deficient environment in step S3 is an inert gas.

3. The preparation method according to claim 1, characterized in that: Step S1 includes the step of pretreating the unintentionally doped silicon-based GaN epitaxial wafer: soaking the unintentionally doped silicon-based GaN epitaxial wafer in acetone, anhydrous ethanol, and deionized water respectively for ultrasonic treatment, taking it out and rinsing it with running deionized water, and then blowing it dry with dry nitrogen.

4. The preparation method according to claim 1, characterized in that: The heating rate of heating to the annealing temperature in step S1 is 12-16°C / min.

5. The preparation method according to claim 1, characterized in that: The cooling rate from cooling to room temperature in step S1 is 12 to 16°C / min.

6. The preparation method according to claim 1, characterized in that: The flow rate of the gas providing the oxygen atmosphere in step S1 is 2000-5000 sccm; or / and the flow rate of the gas providing the oxygen-deficient environment in step S3 is 5000-10000 sccm.

7. The preparation method according to claim 1, characterized in that: In step S2, a method of evenly distributing a layer of metal on the surface of the N-doped gallium oxide epitaxial layer is direct placement or spin coating.

8. The preparation method according to claim 1, characterized in that: The heating rate of heating to the annealing temperature in step S3 is 7-11°C / min.

9. The preparation method according to claim 1, characterized in that: The cooling rate from cooling to room temperature in step S3 is 12 to 16°C / min.

10. A N- and metal-co-doped p-type gallium oxide thin film prepared according to the preparation method according to any one of claims 1 to 9.

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