A p-type beta-ga2o3 single crystal thin film, a preparation method and application thereof

Abstract

The application provides a P-type beta-Ga2O3 single crystal thin film and a preparation method and application thereof, and belongs to the technical field of gallium oxide materials. The P-type beta-Ga2O3 single crystal thin film is obtained by carrying out vapor phase epitaxy thin film growth on the surface of a beta-Ga2O3 single crystal substrate, and nitrogen is used as a carrier gas and a nitride oxide is used as an oxidant in the process of the vapor phase epitaxy thin film growth. In the process of the vapor phase epitaxy thin film growth, N elements are in a thermodynamic unstable state in the gallium oxide crystal and are easy to volatilize from the gallium oxide crystal, therefore, after the carrier gas is replaced by nitrogen, the concentration of N elements in the environment is increased, the volatilization of N elements in the gallium oxide thin film is inhibited, and the efficiency of N doping is improved. In the application, the nitride oxide is used as the oxidant, and the nitrogen is used as the carrier gas, and the two work together, so that the N doping concentration of the P-type beta-Ga2O3 single crystal thin film is improved.

Description

Technical Field

[0001] This invention relates to the field of gallium oxide materials technology, and in particular to a p-type β-Ga2O3 single crystal thin film, its preparation method, and its application. Background Technology

[0002] Gallium oxide (GaO) is an oxide semiconductor with an ultrawide bandgap of 4.7–4.9 eV. Due to its significant advantages such as high breakdown field strength (approximately 8 MeV / cm) and stable physicochemical properties, it has broad application prospects in power devices and everyday ultraviolet detectors, making it the most likely material among ultrawide bandgap semiconductors to achieve commercial application first. High-quality single-crystal growth and substrate development are crucial foundations for the fabrication of high-performance GaO devices. Currently, a major problem restricting the large-scale application of β-Ga2O3 devices is the lack of p-type β-Ga2O3. This is because the valence band top of β-Ga2O3 is too flat, resulting in a large effective hole mass that is difficult to migrate. Furthermore, as an oxide semiconductor, oxygen vacancies easily form and act as donor impurities. Currently, β-Ga2O3 is often used in combination with other materials, such as p-type NiO, to form heterojunctions for device design. However, the p-type conductivity of p-type NiO originates from Ni vacancies and is unstable under actual operating conditions, making it difficult to apply to large-scale commercial production. Therefore, it is necessary to design a preparation route for p-type β-Ga2O3 in order to broaden the application scenarios of β-Ga2O3.

[0003] Nitrogen (N) is an excellent donor element for achieving p-type β-Ga₂O₃, mainly due to the following three aspects: 1. N primarily replaces O atoms in β-Ga₂O₃. The radii of N and O atoms are similar, thus enabling effective substitution; 2. N has a valence state of -3, which, compared to O's -2, allows it to act as a p-type dopant that traps electrons; 3. N is a shallow-energy p-type dopant, which can be effectively excited in β-Ga₂O₃ to achieve the p-type β-Ga₂O₃ effect.

[0004] However, introducing nitrogen (N) into β-Ga₂O₃ is extremely difficult, mainly due to the following reasons: 1. At the high temperatures during single-crystal growth, Ga-O compounds are more stable than Ga-N compounds. Therefore, when growing β-Ga₂O₃ crystals using the melt method, it is impossible to introduce N into β-Ga₂O₃ by introducing nitrogen or nitrogen oxide gases; 2. At the epitaxial growth temperature of β-Ga₂O₃, N₂ is very stable. When nitrogen is introduced during the β-Ga₂O₃ epitaxial growth process, the nitrogen gas always exists in the form of N₂ molecules, making it difficult to enter the film in atomic form, thus failing to achieve the effect of N-doped p-type thin films. Related technologies disclose the introduction of an organic gallium source and N₂O, using argon as the carrier gas, and homogeneous epitaxial growth of p-type gallium oxide material on the β-Ga₂O₃ single-crystal substrate by organometallic chemical vapor deposition. However, the problem of low nitrogen doping concentration in the p-type β-Ga₂O₃ single-crystal thin film still exists. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a p-type β-Ga₂O₃ single crystal thin film, its preparation method, and its applications. The p-type β-Ga₂O₃ single crystal thin film prepared by the method of this invention has a high nitrogen doping concentration.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing p-type β-Ga2O3 single crystal thin films, comprising the following steps:

[0008] A vapor phase epitaxial film is grown on the surface of a β-Ga2O3 single crystal substrate to obtain the P-type β-Ga2O3 single crystal film. Nitrogen gas is used as the carrier gas and nitrogen oxides are used as the oxidant during the vapor phase epitaxial film growth process.

[0009] Preferably, the flow rate of the nitrogen gas is 100~5000 sccm.

[0010] Preferably, the flow rate of the nitrogen gas is 500~4000 sccm.

[0011] Preferably, the nitrogen oxides include one or more of NO, N2O, NO2, N2O3, N2O4, and N2O5.

[0012] Preferably, the growth time of the vapor phase epitaxial film is 0.5~48h.

[0013] Preferably, the vapor phase epitaxial film is grown by metal-organic vapor phase epitaxy (MOVPE) or halide vapor phase epitaxy (HVPE).

[0014] Preferably, the conditions for the metal-organic vapor phase epitaxy method include: a growth temperature of 550~1200℃, a pressure of 10~100mbar, trimethylgallium as the gallium source, a flow rate of trimethylgallium of 10~150sccm, and a flow rate of oxynitride of 1000~10000sccm.

[0015] Preferably, the conditions for the halide vapor phase epitaxy method include: a growth temperature of 600~1200℃, a growth pressure of 10~500 Torr, an HCl flow rate of 10~150 sccm, and a nitrogen oxide flow rate of 100~5000 sccm.

[0016] The present invention also provides a P-type β-Ga2O3 single crystal thin film prepared by the preparation method described above.

[0017] This invention also provides the application of the p-type β-Ga2O3 single crystal thin film described above in the field of gallium oxide devices.

[0018] This invention provides a method for preparing a P-type β-Ga2O3 single crystal thin film, comprising the following steps: performing vapor phase epitaxial film growth on the surface of a β-Ga2O3 single crystal substrate to obtain the P-type β-Ga2O3 single crystal thin film, wherein nitrogen is used as the carrier gas and nitrogen oxides are used as the oxidant during the vapor phase epitaxial film growth process.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] During the growth of vapor phase epitaxial films, nitrogen (N) is in a thermodynamically unstable state in gallium oxide crystals and is easily volatilized from the gallium oxide crystals. Therefore, replacing the carrier gas with nitrogen increases the concentration of N in the environment, inhibits the volatilization of N in the gallium oxide film, and thus improves the efficiency of N doping. This invention uses nitrogen oxides as oxidant and nitrogen as carrier gas to improve the nitrogen doping concentration of P-type β-Ga2O3 single crystal films.

[0021] Furthermore, the growth temperature of the vapor phase epitaxial thin film of the present invention is low.

[0022] The present invention also provides a P-type β-Ga2O3 single crystal thin film prepared by the preparation method described above, which has a high nitrogen doping concentration and high hole concentration, mobility and low resistivity. Attached Figure Description

[0023] Figure 1 The image shown is the AFM image of the p-type β-Ga2O3 single crystal thin film in Example 1.

[0024] Figure 2 The image shown is the AFM image of the P-type β-Ga2O3 single crystal thin film in Example 6. Detailed Implementation

[0025] This invention provides a method for preparing p-type β-Ga2O3 single crystal thin films, comprising the following steps:

[0026] A vapor phase epitaxial film is grown on the surface of a β-Ga2O3 single crystal substrate to obtain the P-type β-Ga2O3 single crystal film. Nitrogen gas is used as the carrier gas and nitrogen oxides are used as the oxidant during the vapor phase epitaxial film growth process.

[0027] In this invention, it is preferable to first grow a high-quality bulk β-Ga2O3 crystal, and then process the bulk β-Ga2O3 crystal to obtain the β-Ga2O3 single crystal substrate.

[0028] In this invention, the growth method is preferably the straight-pull method, the mold method, the casting method, the floating zone method, or the vertical Bridgman method. This invention does not impose any special limitations on the growth parameters, and any method known to those skilled in the art can be used.

[0029] In this invention, the flow rate of nitrogen is preferably 100~5000 sccm, more preferably 500~4000 sccm, and specifically can be 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500 or 5000 sccm.

[0030] In this invention, the nitrogen oxide preferably includes one or more of NO, N2O, NO2, N2O3, N2O4 and N2O5. The higher the valence state of N in the nitrogen oxide, the easier it is for N to gain electrons in the reaction, resulting in stronger oxidizing properties and making it more conducive to the growth of epitaxial gallium oxide.

[0031] In this invention, the growth time of the vapor phase epitaxial film is preferably 0.5 to 48 hours, specifically 0.5, 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45 or 48 hours.

[0032] In this invention, the vapor phase epitaxial film growth is preferably performed using metal-organic vapor phase epitaxy or halide vapor phase epitaxy.

[0033] In this invention, the preferred conditions for the metal-organic vapor phase epitaxy method include: a growth temperature of 550~1200℃, specifically 550, 600, 700, 800, 900, 1000, 1100 or 1200℃; a pressure of 10~100 mbar, specifically 10, 25, 30, 40, 50, 60, 70, 80, 90 or 100 mbar; trimethylgallium as the gallium source; a trimethylgallium flow rate of 10~150 sccm, specifically 10, 50, 100 or 150 sccm; and a nitrogen oxide flow rate of 1000~10000 sccm, specifically 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000 or 10000 sccm.

[0034] In this invention, the preferred conditions for the halide vapor phase epitaxy method include: a growth temperature of 600~1200℃, specifically 600, 650, 700, 800, 1000 or 1200℃; a growth pressure of 10~500 Torr, specifically 10, 50, 100, 150, 200, 250, 300, 350, 400, 450 or 500 Torr; an HCl flow rate of 10~150 sccm, specifically 10, 50, 100 or 150 sccm; and a nitrogen oxide flow rate of 100~5000 sccm, specifically 100, 500, 1000, 2000, 3000, 4000 or 5000 sccm.

[0035] In this invention, because nitrogen (N) is thermodynamically unstable in gallium oxide crystals at high epitaxial temperatures and easily volatilizes from the crystal, replacing the carrier gas with nitrogen increases the concentration of N in the environment, suppressing the volatilization of N in the gallium oxide film and thus improving the efficiency of N doping. Furthermore, the vapor phase epitaxial film growth temperature described in this invention is low, and nitrogen oxides are generally easy to decompose at high temperatures. Taking N2O as an example, it begins to decompose above 300°C, decomposes significantly at 500°C, and completely decomposes into nitrogen and oxygen above 900°C. Therefore, lowering the temperature helps to avoid the decomposition of nitrogen oxides during the epitaxial film process, thereby improving the utilization rate of nitrogen oxides and the nitrogen doping concentration.

[0036] The present invention also provides a P-type β-Ga2O3 single crystal thin film prepared by the preparation method described above. The present invention uses nitrogen oxides as oxidant and nitrogen as carrier gas to improve the nitrogen doping concentration of the P-type β-Ga2O3 single crystal thin film. The P-type β-Ga2O3 single crystal thin film has a high nitrogen doping concentration and high hole concentration, mobility and low resistivity.

[0037] This invention also provides the application of the p-type β-Ga2O3 single crystal thin film described above in the field of gallium oxide devices.

[0038] The present invention does not impose any special limitation on the specific method of application, and any method known to those skilled in the art can be used.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1

[0041] The preparation of p-type β-Ga2O3 single crystal thin films includes the following steps:

[0042] 1. First, high-quality bulk β-Ga2O3 crystals are grown using the Czochralski method, and then the crystals are processed into β-Ga2O3 single crystal substrates.

[0043] 2. P-type β-Ga2O3 single crystal thin films were grown using metal-organic vapor phase epitaxy at a growth temperature of 600℃, a pressure of 25mbar, a trimethylgallium flow rate of 50sccm, an N2O flow rate of 1000sccm, and N2 as the carrier gas at a flow rate of 500sccm. The growth time was 0.5h.

[0044] Example 2

[0045] The preparation of p-type β-Ga2O3 single crystal thin films includes the following steps:

[0046] 1. First, high-quality bulk β-Ga2O3 crystals are grown using the Czochralski method, and then the crystals are processed into β-Ga2O3 single crystal substrates.

[0047] 2. P-type β-Ga2O3 single crystal thin films were grown using metal-organic vapor phase epitaxy at a growth temperature of 600℃, a pressure of 25mbar, a trimethylgallium flow rate of 50sccm, an N2O flow rate of 5000sccm, and N2 as the carrier gas at a flow rate of 500sccm. The growth time was 0.5h.

[0048] Example 3

[0049] The preparation of p-type β-Ga2O3 single crystal thin films includes the following steps:

[0050] 1. First, high-quality bulk β-Ga2O3 crystals are grown using the Czochralski method, and then the crystals are processed into β-Ga2O3 single crystal substrates.

[0051] 2. P-type β-Ga2O3 single crystal thin films were grown using metal-organic vapor phase epitaxy at a growth temperature of 600℃, a pressure of 25mbar, a trimethylgallium flow rate of 50sccm, an N2O flow rate of 10000sccm, and N2 as the carrier gas at a flow rate of 500sccm. The growth time was 0.5h.

[0052] Comparative Example 1

[0053] Same as Example 1, except that N2 is replaced with argon.

[0054] Example 4

[0055] Same as Example 1, except that N2O is replaced with N2O3.

[0056] Example 5

[0057] Same as Example 1, except that N2O is replaced with N2O5.

[0058] Example 6

[0059] Same as Example 1, except that the growth temperature is 550°C.

[0060] Example 7

[0061] Same as Example 1, except that the growth temperature is 650°C.

[0062] Example 8

[0063] The preparation of p-type β-Ga2O3 single crystal thin films includes the following steps:

[0064] 1. First, high-quality bulk β-Ga2O3 crystals are grown using the Czochralski method, and then the crystals are processed into β-Ga2O3 single crystal substrates.

[0065] 2. A halide vapor phase epitaxy method was adopted, with a growth temperature of 700℃, a growth pressure of 200 Torr, an HCl flow rate of 10 sccm, an N2O flow rate of 100 sccm, and N2 as the carrier gas with a flow rate of 2000 sccm. The growth time was 3 h, and then P-type β-Ga2O3 single crystal thin film was obtained by chemical mechanical polishing.

[0066] Example 9

[0067] The preparation of p-type β-Ga2O3 single crystal thin films includes the following steps:

[0068] 1. First, high-quality bulk β-Ga2O3 crystals are grown using the Czochralski method, and then the crystals are processed into β-Ga2O3 single crystal substrates.

[0069] 2. P-type β-Ga2O3 single crystal thin films were prepared by halide vapor phase epitaxy at a growth temperature of 700℃, a growth pressure of 200 Torr, an HCl flow rate of 10 sccm, an N2O flow rate of 1000 sccm, and N2 as the carrier gas at a flow rate of 2000 sccm for a growth time of 3 h.

[0070] Example 10

[0071] The preparation of p-type β-Ga2O3 single crystal thin films includes the following steps:

[0072] 1. First, high-quality bulk β-Ga2O3 crystals are grown using the Czochralski method, and then the crystals are processed into β-Ga2O3 single crystal substrates.

[0073] 2. P-type β-Ga2O3 single crystal thin films were prepared by halide vapor phase epitaxy at a growth temperature of 700℃, a growth pressure of 200 Torr, an HCl flow rate of 10 sccm, an N2O flow rate of 5000 sccm, and N2 as the carrier gas at a flow rate of 2000 sccm for a growth time of 3 h.

[0074] Example 11

[0075] Same as Example 9, except that the growth temperature is 650°C.

[0076] Example 12

[0077] Same as Example 9, except that the growth temperature is 600°C.

[0078] Example 13

[0079] Same as in Example 1, except that the carrier gas flow rate is 100 sccm.

[0080] Example 14

[0081] Same as Example 1, except that the carrier gas flow rate is 4000 sccm.

[0082] Example 15

[0083] Same as Example 1, except that the carrier gas flow rate is 5000 sccm.

[0084] Comparative Example 2

[0085] Same as Example 9, except that N2 is replaced with argon.

[0086] Figure 1The image shown is the AFM pattern of the p-type β-Ga2O3 single crystal thin film in Example 1, with a roughness of 1.5 nm. Figure 2 The image shown is the AFM image of the P-type β-Ga2O3 single crystal thin film in Example 6, with a roughness of 0.6 nm. It can be seen that the surface roughness of the P-type β-Ga2O3 single crystal thin film prepared by the present invention is good.

[0087] Table 1 shows the test results of the P-type β-Ga2O3 single crystal thin films prepared in the examples and comparative examples. It can be seen that the present invention uses oxynitride as an oxidant and nitrogen as a carrier gas to improve the nitrogen doping concentration of the P-type β-Ga2O3 single crystal thin film. The P-type β-Ga2O3 single crystal thin film has a high nitrogen doping concentration, a small half-width at half-maximum of the rocking curve, and an ordered crystal structure. It has good quality and performance, and has high hole concentration, mobility and low resistivity. In addition, the higher the valence state of N in oxynitride, the easier it is for N to gain electrons in the reaction, which has stronger oxidizing power and is more conducive to the growth of epitaxial gallium oxide. Moreover, the growth temperature of the present invention is as low as 550℃.

[0088] Table 1. Test results of p-type β-Ga2O3 single crystal thin films prepared in the examples and comparative examples.

[0089]

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a p-type β-Ga₂O₃ single crystal thin film, characterized in that, Includes the following steps: A vapor phase epitaxial film was grown on the surface of a β-Ga2O3 single crystal substrate to obtain the P-type β-Ga2O3 single crystal film. Nitrogen was used as the carrier gas and nitrogen oxides were used as the oxidant during the vapor phase epitaxial film growth process. The flow rate of nitrogen was 100~5000 sccm. The vapor phase epitaxial film is grown by metal-organic vapor phase epitaxy or halide vapor phase epitaxy. The conditions for the metal-organic vapor phase epitaxy method include: a growth temperature of 550~1200℃, a pressure of 10~100mbar, trimethylgallium as the gallium source, a flow rate of trimethylgallium of 10~150sccm, and a flow rate of oxynitride of 1000~10000sccm. The conditions for the halide vapor phase epitaxy method include: growth temperature of 600~1200℃, growth pressure of 10~500 Torr, HCl flow rate of 10~150 sccm, and nitrogen oxide flow rate of 100~5000 sccm.

2. The preparation method according to claim 1, characterized in that, The flow rate of the nitrogen gas is 500~4000 sccm.

3. The preparation method according to claim 1, characterized in that, The nitrogen oxides include one or more of NO, N2O, NO2, N2O3, N2O4, and N2O5.

4. The preparation method according to claim 1, characterized in that, The growth time of the vapor phase epitaxial film is 0.5~48h.

Images