Gallium oxide epitaxial growth method

Abstract

The invention provides a gallium oxide epitaxial growth method, and belongs to the field of crystal preparation. According to the method, beveling processing is carried out on the (001) surface of the beta-Ga2O3 substrate to obtain a beveled (001) substrate, the beveling processing direction is the [-100] direction, and the angle is 0.1-6 degrees. According to the invention, beveling processing is carried out on a beta-Ga2O3 (001) surface substrate towards a [-100] direction to expose a specific substrate surface step surface (a step structure taking a (-201) surface as a step side surface), so that the substrate surface structure which easily causes generation of twin crystal defects is avoided; a step structure with a (100) surface as a step side surface caused by beveling towards a [100] direction and other possible directions is avoided, spontaneous formation of twin crystal defects caused by the structure is prevented, the method can be applied to epitaxial growth, a high-quality epitaxial film is obtained, and the crystal quality in the beta-Ga2O3 epitaxial process is improved.

Description

Technical Field

[0001] This invention relates to the field of crystal preparation technology, and in particular to a method for epitaxial growth of gallium oxide. 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 solar-blind ultraviolet detectors, making it the material most likely to achieve commercial application first among ultrawide bandgap semiconductors. High-quality single-crystal growth and substrate development are crucial foundations for achieving high-performance GaO devices.

[0003] To produce high-performance β-Ga2O3 devices, an epitaxial thin film layer needs to be fabricated on a β-Ga2O3 substrate. Currently, β-Ga2O3 epitaxial methods include metal-organic chemical vapor deposition (MOCVD), halide vapor phase epitaxy (HVPE), and molecular beam epitaxy (MBE). Due to the lamellar atomic structure in β-Ga2O3 crystals, when a β-Ga2O3 single-crystal substrate with the (001) plane is obliquely cut along a specific direction, a distinctly different step structure is exposed. This step structure is beneficial for forming good step flow growth during epitaxy, improving the crystal quality of the epitaxial layer. However, due to the low symmetry of β-Ga2O3, when its (001) facet substrate is obliquely cut along a series of directions, such as obliquely cutting towards the

[100] direction, the exposed step surface will induce a certain type of twin defect to spontaneously form in the epitaxy, which is difficult to avoid by technical means. Therefore, it is necessary to control the oblique cutting direction of the β-Ga2O3 (001) facet substrate to avoid the aforementioned step structure that leads to defect generation, so as to improve the crystal quality in the epitaxial process.

[0004] Currently, the existing related solutions are as follows: A continuous bevel is formed on the upper surface of a (001) crystal plane gallium oxide substrate. An epitaxial film is grown on the (001) crystal plane gallium oxide substrate with the continuous bevel. By beveling the (001) plane substrate towards the

[100] crystal plane, the

[010] crystal plane, or both directions at ≥0.5°, step flow growth is achieved. The bevel setting results in low-roughness, high-quality homoepitaxial growth on the (001) crystal plane gallium oxide substrate. However, due to the low symmetry of β-Ga2O3 crystals, the atomic-level steps exposed on the substrate surface by beveling the (001) plane substrate towards the

[100] crystal plane or other specific crystal plane directions can easily become a cause of spontaneously formed twin defects, greatly reducing crystal quality. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for epitaxial growth of gallium oxide. The method of the present invention avoids the step structure with the (100) plane as the step side caused by oblique cutting in the

[100] direction and other possible directions, and prevents the spontaneous formation of twin defects caused by such structure. It can be applied to epitaxial growth to obtain high-quality epitaxial films.

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

[0007] This invention provides a method for gallium oxide epitaxial growth, comprising the following steps:

[0008] The (001) surface of the β-Ga2O3 substrate is beveled to obtain a beveled (001) substrate. The beveling direction is [-100] and the angle is 0.1° to 6°.

[0009] Gallium oxide epitaxial growth is performed on the obliquely cut (001) substrate surface.

[0010] Preferably, the angle of the beveling process is 1° to 5°.

[0011] Preferably, the angle of the beveling process is 2° to 4°.

[0012] Preferably, the process further includes heat treatment of the obliquely cut (001) substrate before the gallium oxide epitaxial growth.

[0013] Preferably, the atmosphere for the heat treatment is an oxygen-nitrogen mixture, wherein the volume percentage of oxygen in the oxygen-nitrogen mixture is 0% to 100% and is neither 0% nor 100%, and the temperature for the heat treatment is 800 to 1500°C and the time is 0.5 to 48 hours.

[0014] Preferably, the heat treatment temperature is 1000–1200°C and the time is 5–24 hours.

[0015] Preferably, the gallium oxide epitaxial growth is performed using metal-organic chemical vapor deposition (MOCVD), wherein the MOCVD temperature is 400–1200°C, the pressure is 5–100 mbar, the trimethylgallium flow rate is 10–150 sccm, the oxygen flow rate is 1000–10000 sccm, and the time is 0.5–48 h.

[0016] Preferably, the gallium oxide epitaxial growth is performed using halide vapor phase epitaxy, wherein the temperature of halide vapor phase epitaxy is 400–1200°C, the growth pressure is 10–500 Torr, the HCl flow rate is 10–150 sccm, the oxygen flow rate is 100–5000 sccm, the carrier gas flow rate is 100–5000 sccm, and the time is 0.5–48 h.

[0017] Preferably, the gallium oxide epitaxial growth is performed using metal-organic vapor phase epitaxy, wherein the temperature of the metal-organic vapor phase epitaxy is 400–1200°C, the pressure is 5–100 mbar, the trimethylgallium flow rate is 5–150 sccm, the oxygen flow rate is 100–10000 sccm, and the time is 0.5–48 h.

[0018] Preferably, the gallium oxide epitaxial growth is performed using molecular beam epitaxy, wherein the temperature of the molecular beam epitaxy is 400–1200 °C and the Ga beam current equivalent pressure is 1 × 10⁻⁶. -7 ~1×10 -6 mbar, oxygen plasma flow rate 0.5–4 sccm, oxygen plasma power 300 W, duration 0.5–48 h

[0019] The present invention provides a method for gallium oxide epitaxial growth, comprising the following steps: performing a bevel cutting process on the (001) surface of a β-Ga2O3 substrate to obtain a beveled (001) substrate, wherein the bevel cutting process is performed in the [-100] direction and the angle is 0.1° to 6°; and performing gallium oxide epitaxial growth on the surface of the beveled (001) substrate.

[0020] Compared with the prior art, the technical principles of the present invention are as follows:

[0021] 1. In a β-Ga2O3 crystal, the standard surface of the (001) substrate projected along the

[010] crystallographic direction is as follows: Figure 1 As shown. Due to the layered atomic stacking structure of gallium oxide, there are several possible (001) plane atomic structures. Among them, density functional theory calculations show that, for example... Figure 1 The (001) surface structure shown has the lowest surface energy density, at 1.26 J / m². 2 .

[0022] 2. In a β-Ga2O3 crystal, the standard surface of the (001) substrate projected along the

[010] crystallographic direction is as follows: Figure 1 As shown, due to the monoclinic crystal structure of gallium oxide, the (001) plane is not perpendicular to the crystallographic direction of

[001] .

[0023] 3. When the (001) surface of a β-Ga2O3 crystal is obliquely cut in different directions, specific atomic-level step structures are formed at high temperatures (800–1200 °C). For example, oblique cutting along a specific

[100] crystallographic direction exposes an atomic-level step structure with the (100) plane as the step surface, while oblique cutting along a specific [-100] crystallographic direction exposes an atomic-level step structure with the (-201) plane as the step surface. Figure 2As shown. Both (100) and (-201) structures are surface structures with the lowest energy density calculated using density functional theory. The surface energy density of the (100) surface is 0.60 J / m². 2 The surface energy density of the (-201) plane is 0.93 J / m². 2 .

[0024] 4. Because β-Ga2O3 crystal belongs to the monoclinic crystal system, its low symmetry causes the (001) substrate to be obliquely cut along the

[100] direction, resulting in... Figure 2 A twinning defect structure is generated within the dashed rectangular frame, such as... Figure 3 As shown in the dashed box. This structure is located at the junction of the (100) step surface and the (001) surface, originally Figure 2 The (100) step surface and (001) surface within the dashed box are replaced by (100) surface twin boundaries and (001) / (10-1) twin boundaries, respectively, exposing the (-201) surface. First-principles calculations show that the interfacial energy density of the (100) twin boundary is 0.008 J / m². 2 The energy density of the (001) / (10-1) twin boundary is 0.35 J / m. 2 .

[0025] 5. Based on the geometric relationships in the β-Ga₂O₃ crystal structure, Figure 2 Within the dashed box, the total interfacial structure energy density σ of the exposed (001) and (100) surfaces is represented. A for:

[0026] σ A =0.60J / m 2 *x+1.26J / m 2 *2.12*x=3.27J / m 2 x,

[0027] Among them, 0.60 J / m 2 The surface energy density of the β-Ga2O3(100) surface structure is 1.26 J / m. 2 Let x be the surface energy density of the β-Ga2O3(001) surface structure. Figure 2 The result is calculated based on geometric relationships and will be Figure 3 The area of ​​the (100) surface covered by the intermediate twin structure (i.e. Figure 3 The length of the pentagon within the dashed box represents the area. Figure 3 The area of ​​the line connecting the pentagons within the dashed box in the direction perpendicular to the plane. Because Figure 3 The image shows the crystal structure projected onto the paper along the

[010] direction (perpendicular to the paper plane). Therefore, this structure extends infinitely in the direction perpendicular to the plane. Because... Figure 3 The dotted line, the triangle line, and the pentagon line all extend equally in the direction perpendicular to the paper. Therefore, in calculations, the distances extended along the paper can cancel each other out. The lengths of the dotted line, the triangle line, and the pentagon line can represent the three-dimensional area formed by the structure after extending along the paper. 2.12*x is... Figure 2 The result is calculated based on geometric relationships and will be Figure 3 The area of ​​the (001) surface covered by the intermediate twin structure (i.e. Figure 3 (Length of the triangle within the dashed box).

[0028] 6. Based on the geometric relationships in the β-Ga₂O₃ crystal structure, Figure 3 Within the dashed box, the total interfacial energy density σ represents the exposed (-201) surface and the three interfaces of the (100) twin boundary and the (001) / (10-1) twin boundary. A for:

[0029] σ A =0.008J / m 2 *x+0.35J / m 2 *2.12*x+0.93J / m 2 *2.55*x=3.12J / m 2 x,

[0030] Among them, 0.008J / m 2 The interfacial energy density of the β-Ga2O3(100) twin boundary is 0.35 J / m. 2 The interfacial energy density of the β-Ga2O3(001) / (10-1) twin boundary is 0.93 J / m. 2 is the surface energy density of the β-Ga2O3(-201) surface structure. x is... Figure 3 The area of ​​the (100) surface covered by the intermediate twin structure (i.e. Figure 3 The length of the pentagonal dotted line within the dashed box), 2.12*x is Figure 3 The area of ​​the (001) surface covered by the intermediate twin structure (i.e. Figure 3 The length of the triangular dotted line within the dashed box), 2.55*x is Figure 3 The area of ​​the (-201) surface exposed by the intermediate twin structure (i.e. Figure 3 (Length of the dotted line within the dashed box).

[0031] 7. Based on the analysis in points 5 and 6, we can conclude that... Figure 3 The total interfacial energy density of the twinned structure is 3.12 J / m³. 2 Below Figure 2 The total interfacial structural energy density of the freely exposed structure is 3.27 J / m³. 2Therefore, it will spontaneously form during the epitaxial process, leading to the destruction of crystal quality.

[0032] 8. Therefore, the present invention proposes to bevel the (001)β-Ga2O3 substrate in the [-100] direction to expose the Figure 3 and Figure 2 The (-201) step exposed surface structure on the right side of the middle section is used to suppress the formation of twin defects mentioned above and improve the quality of crystal growth.

[0033] This invention proposes to beveling a β-Ga2O3 (001) substrate toward the [-100] direction to expose a specific substrate surface step (a step structure with the (-201) plane as the step side), thereby avoiding the substrate surface structure that easily leads to twin defects. This avoids the step structure with the (100) plane as the step side caused by beveling toward the

[100] direction and other possible directions, and prevents the spontaneous formation of twin defects caused by this structure. It can be applied to epitaxial growth to obtain high-quality epitaxial films and improve the crystal quality in the β-Ga2O3 epitaxial process. Attached Figure Description

[0034] Figure 1 This is a schematic diagram showing the relative relationship between the β-Ga2O3(001) plane substrate and the crystallographic orientation.

[0035] Figure 2 A schematic diagram of atomic-level steps exposed by oblique cutting of a β-Ga2O3(001) substrate toward the

[100] and [-100] directions;

[0036] Figure 3 After the β-Ga2O3(001) substrate is obliquely cut towards the

[100] direction, the original step structure in the dashed box will be replaced by twin defects;

[0037] Figure 4 The image is an atomic force microscope (AFM) image of a stepped structure obtained by beveling in the [-100] direction on a β-Ga2O3(001) substrate in Example 1 and then heat-treated.

[0038] Figure 5 An atomic force microscope (AFM) image showing the merging of steps on the surface of a gallium oxide (001) substrate after excessively high temperatures and prolonged exposure;

[0039] Figure 6 An atomic force microscope (AFM) image of the epitaxial thin film obtained in Example 1;

[0040] Figure 7 An atomic force microscope (AFM) image of the epitaxial thin film obtained in Example 2;

[0041] Figure 8 An atomic force microscope (AFM) image of the epitaxial thin film obtained in Example 3;

[0042] Figure 9 An atomic force microscope (AFM) image of the epitaxial thin film obtained in Example 4;

[0043] Figure 10 An atomic force microscope (AFM) image of the epitaxial thin film obtained in Example 5. Detailed Implementation

[0044] This invention provides a method for gallium oxide epitaxial growth, comprising the following steps:

[0045] The (001) surface of the β-Ga2O3 substrate is beveled to obtain a beveled (001) substrate. The beveling direction is [-100] and the angle is 0.1° to 6°.

[0046] Gallium oxide epitaxial growth is performed on the obliquely cut (001) substrate surface.

[0047] The present invention performs a bevel cutting process on the (001) surface of a β-Ga2O3 substrate to obtain a beveled (001) substrate. The bevel cutting process is performed in the [-100] direction with an angle of 0.1° to 6°.

[0048] In this invention, the size of the β-Ga2O3 substrate is preferably 2 inches or more. This invention does not have any special limitation on the source of the β-Ga2O3 substrate, and any method known to those skilled in the art can be used, such as the Czochralski method, the mold method, the casting method, the floating zone method, the vertical Bridgman method, etc., to prepare the β-Ga2O3 substrate.

[0049] In this invention, the angle of the beveling process is preferably 1° to 5°, more preferably 2° to 4°, and specifically can be 0.1°, 0.5°, 1°, 2°, 3°, 4°, 5° or 6°.

[0050] The present invention does not impose any particular limitation on the specific method of the beveling process, and any method used for gallium oxide crystal processing can be used.

[0051] After obtaining the obliquely cut (001) substrate, the present invention performs gallium oxide epitaxial growth on the surface of the obliquely cut (001) substrate.

[0052] In this invention, the process of growing gallium oxide epitaxially preferably includes heat treatment of the obliquely cut (001) substrate.

[0053] In this invention, the heat treatment serves to pre-expose atomic-level steps, as illustrated in the schematic diagram of the resulting surface step structure. Figure 4 As shown.

[0054] In this invention, the atmosphere for heat treatment is preferably an oxygen-nitrogen mixture, wherein the volume percentage of oxygen in the oxygen-nitrogen mixture is preferably 0% to 100% and not 0% or 100%, specifically 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%. The temperature for heat treatment is preferably 800 to 1500°C, more preferably 1000 to 1200°C, specifically 800, 900, 1000, 1100, 1200, 1300, 1400, or 1500°C. The time is preferably 0.5 to 48 hours, more preferably 5 to 24 hours, specifically 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 48 hours. Different heat treatment times and temperatures affect… Figure 4 The morphology of the substrate surface steps is important; excessively high temperatures and excessively long times can cause deformation and quality degradation of the substrate surface steps, while excessively low temperatures and excessively short times make it difficult to form them. Figure 4 The diagram shows regular surface steps. Therefore, suitable temperature and time configurations are required, such as heat treatment at 800°C for 24 hours or at 1200°C for 4 hours. A combination of low temperature + long time or high temperature + short time can produce good surface steps. Furthermore, oxygen concentration also affects the formation of gallium oxide (001) surface steps. In a high oxygen concentration environment, the temperature for forming appropriate steps decreases and the time is shortened; in a low oxygen concentration environment, the temperature for forming appropriate steps increases and the time is prolonged. For example, as shown... Figure 5 As shown, when the temperature and time are too high, the gallium oxide (001) substrate surface exhibits a step merging phenomenon, which is not conducive to subsequent epitaxy.

[0055] In this invention, without the aforementioned heat treatment, it is impossible to pre-form high-quality steps. However, stable step flow growth can still be achieved in epitaxy, and the generation of twin defects can be suppressed. This is because the substrate is usually heated to 800–1200°C and held at that temperature for a certain period of time before subsequent gallium oxide epitaxial growth. This operation is equivalent to heat treatment, meaning that the aforementioned heat treatment can also be omitted.

[0056] In this invention, the gallium oxide epitaxial growth is preferably performed using metal-organic chemical vapor deposition (MOCVD). The MOCVD temperature is preferably 400–1200°C, the pressure is preferably 10–100 mbar, the trimethylgallium flow rate is preferably 10–150 sccm, the oxygen flow rate is preferably 1000–10000 sccm, and the time is preferably 0.5–48 h.

[0057] In this invention, the gallium oxide epitaxial growth is preferably performed using halide vapor phase epitaxy. The preferred temperature for halide vapor phase epitaxy is 400–1200°C, the preferred growth pressure is 10–500 Torr, the preferred HCl flow rate is 10–150 sccm, the preferred oxygen flow rate is 100–5000 sccm, the preferred carrier gas flow rate is 100–5000 sccm, and the preferred time is 0.5–48 h.

[0058] In this invention, the gallium oxide epitaxial growth is preferably performed using metal-organic vapor phase epitaxy (MOV). The preferred temperature for MOV is 400–1200°C, the preferred pressure is 5–100 mbar, the preferred trimethylgallium flow rate is 5–150 sccm, the preferred oxygen flow rate is 100–10000 sccm, and the preferred time is 0.5–48 h.

[0059] In this invention, the gallium oxide epitaxial growth is preferably performed using molecular beam epitaxy, the temperature of which is preferably 400–1200°C, and the Ga beam current equivalent pressure is preferably 1 × 10⁻⁶. -7 ~1×10 -6 The preferred oxygen plasma flow rate is 0.5–4 sccm, the preferred oxygen plasma power is 300 W, and the preferred plasma duration is 0.5–48 h.

[0060] In this invention, a dopant is preferably added during the gallium oxide epitaxial growth process, and the dopant preferably includes one or more of silicon, tin, iron and magnesium.

[0061] In this invention, the amount of dopant used in the epitaxial growth of gallium oxide varies depending on the method used. Preferably, the concentration of the dopant in the thin film sample obtained after epitaxy is 1×10⁻⁶. 17 ~1×10 20 cm -3 The concentration here is calculated from the concentration of doped atoms in the thin film obtained through epitaxy.

[0062] 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.

[0063] Example 1

[0064] 1. Growing high-quality bulk β-Ga2O3 crystals (2 inches in size) using the Czochralski method.

[0065] 2. The (001) plane of the β-Ga2O3 crystal is beveled in the [-100] direction at an angle of 0.1°.

[0066] 3. The beveled (001) substrate was subjected to heat treatment in a mixed atmosphere of oxygen and nitrogen, with oxygen comprising 10% by volume. The heat treatment temperature was 1200℃, and the heat treatment time was 4 hours. After treatment, the following was obtained: Figure 4 An atomic force microscope (AFM) image of the surface step structure shown.

[0067] 4. Gallium oxide epitaxial growth is performed on the surface of the substrate obtained in step 3. The epitaxial method is metal-organic chemical vapor deposition, the growth temperature is 1200℃, the pressure is 100mbar, the trimethylgallium flow rate is 150sccm, the oxygen flow rate is 10000sccm, the dopant silicon used for growth (the flow rate of the dopant silicon raw material SiH4 is 10sccm), and the growth time is 48h.

[0068] Figure 6 The image shown is an atomic force microscope (AFM) image of the epitaxial film obtained in Example 1. It can be seen that by using the gallium oxide (001) substrate processed in Example 1, good atomic-level steps on the substrate surface can be obtained. Using this substrate for epitaxy can yield high-quality epitaxial films.

[0069] Example 2

[0070] 1. Growing high-quality bulk β-Ga2O3 crystals (3 inches in size) using the Czochralski method.

[0071] 2. The (001) plane of the β-Ga2O3 crystal is beveled in the [-100] direction at an angle of 0.1°.

[0072] 3. Gallium oxide epitaxial growth is performed on the surface of the substrate obtained in step 2. The epitaxial method is metal-organic chemical vapor deposition, the growth temperature is 1200℃, the pressure is 100mbar, the trimethylgallium flow rate is 150sccm, the oxygen flow rate is 10000sccm, the dopant silicon used for growth (the flow rate of the dopant silicon raw material SiH4 is 10sccm), and the growth time is 48h.

[0073] Figure 7 The image shown is an atomic force microscope (AFM) image of the epitaxial film obtained in Example 2. It can be seen that by using the gallium oxide (001) substrate processed in Example 2, good atomic-level steps on the substrate surface can be obtained. Using this substrate for epitaxy can yield high-quality epitaxial films.

[0074] Example 3

[0075] 1. Growing high-quality bulk β-Ga2O3 crystals (2 inches in size) using the Czochralski method.

[0076] 2. The (001) plane of the β-Ga2O3 crystal is beveled in the [-100] direction at an angle of 6°.

[0077] 3. The obliquely cut (001) substrate is subjected to heat treatment. The heat treatment atmosphere is a mixture of oxygen and nitrogen, wherein the volume percentage of oxygen is 10%, the heat treatment temperature is 800℃, and the heat treatment time is 24h.

[0078] 4. Gallium oxide epitaxial growth is performed on the surface of the substrate obtained in step 3. The epitaxial method is metal-organic chemical vapor deposition, the growth temperature is 1200℃, the pressure is 100mbar, the trimethylgallium flow rate is 150sccm, the oxygen flow rate is 10000sccm, the dopant silicon used for growth (the flow rate of the dopant silicon raw material SiH4 is 10sccm), and the growth time is 48h.

[0079] Figure 8 The image shown is an atomic force microscope (AFM) image of the epitaxial film obtained in Example 3. It can be seen that by using the gallium oxide (001) substrate processed in Example 3, good atomic-level steps on the substrate surface can be obtained. Using this substrate for epitaxy can yield high-quality epitaxial films.

[0080] Example 4

[0081] 1. Growing high-quality bulk β-Ga2O3 crystals (2 inches in size) using the Czochralski method.

[0082] 2. The (001) plane of the β-Ga2O3 crystal is beveled in the [-100] direction at an angle of 0.1°.

[0083] 3. The obliquely cut (001) substrate is subjected to heat treatment. The heat treatment atmosphere is a mixture of oxygen and nitrogen, wherein the volume percentage of oxygen is 10%, the heat treatment temperature is 1500℃, and the heat treatment time is 1h.

[0084] 4. Gallium oxide epitaxial growth is performed on the surface of the substrate obtained in step 3. The epitaxial method is metal-organic chemical vapor deposition, the growth temperature is 1200℃, the pressure is 100mbar, the trimethylgallium flow rate is 150sccm, the oxygen flow rate is 10000sccm, the dopant silicon used for growth (the flow rate of the dopant silicon raw material SiH4 is 10sccm), and the growth time is 48h.

[0085] Figure 9The image shown is an atomic force microscope (AFM) image of the epitaxial film obtained in Example 4. It can be seen that by using the gallium oxide (001) substrate processed in Example 4, good atomic-level steps on the substrate surface can be obtained. Using this substrate for epitaxy can yield high-quality epitaxial films.

[0086] Example 5

[0087] 1. Growing high-quality bulk β-Ga2O3 crystals (2 inches in size) using the Czochralski method.

[0088] 2. The (001) plane of the β-Ga2O3 crystal is beveled in the [-100] direction at an angle of 0.1°.

[0089] 3. The obliquely cut (001) substrate is subjected to heat treatment. The heat treatment atmosphere is a mixture of oxygen and nitrogen, wherein the volume percentage of oxygen is 10%, the heat treatment temperature is 1500℃, and the heat treatment time is 1h.

[0090] 4. Gallium oxide epitaxial growth is performed on the surface of the substrate obtained in step 3. The epitaxial method is halide vapor phase epitaxy, the growth temperature is 1200℃, the growth pressure is 500 Torr, the HCl flow rate is 150 sccm, the oxygen flow rate is 5000 sccm, the carrier gas flow rate is 5000 sccm, the dopant silicon used for growth (the flow rate of the dopant silicon raw material SiH4 is 10 sccm), and the growth time is 48h.

[0091] Figure 10 The image shown is an atomic force microscope (AFM) image of the epitaxial film obtained in Example 5. It can be seen that by using the gallium oxide (001) substrate processed in Example 5, good atomic-level steps can be obtained on the substrate surface. Using this substrate for epitaxy can yield high-quality epitaxial films.

[0092] Depend on Figures 6-10 It can be seen that by obliquely cutting the (001) substrate, step flow growth results can be obtained under different epitaxial conditions.

[0093] 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 epitaxial growth of gallium oxide, characterized in that, Includes the following steps: The (001) surface of the β-Ga2O3 substrate is beveled to obtain a beveled (001) substrate. The beveling direction is [-100] and the angle is 0.1° to 6°. Gallium oxide epitaxial growth is performed on the obliquely cut (001) substrate surface.

2. The method according to claim 1, characterized in that, The angle of the beveling process is 1° to 5°.

3. The method according to claim 2, characterized in that, The angle of the beveling process is 2° to 4°.

4. The method according to claim 1, characterized in that, The process of growing gallium oxide epitaxially also includes heat treatment of the obliquely cut (001) substrate.

5. The method according to claim 4, characterized in that, The atmosphere for the heat treatment is an oxygen-nitrogen mixture, wherein the volume percentage of oxygen in the oxygen-nitrogen mixture is 0% to 100% and is neither 0% nor 100%, and the temperature for the heat treatment is 800 to 1500°C and the time is 0.5 to 48 hours.

6. The method according to claim 5, characterized in that, The heat treatment is performed at a temperature of 1000–1200℃ for 5–24 hours.

7. The method according to claim 1, characterized in that, The gallium oxide epitaxial growth is performed using metal-organic chemical vapor deposition (MOCVD), wherein the temperature of MOCVD is 400–1200 °C, the pressure is 5–100 mbar, the trimethylgallium flow rate is 10–150 sccm, the oxygen flow rate is 1000–10000 sccm, and the time is 0.5–48 h.

8. The method according to claim 1, characterized in that, The gallium oxide epitaxial growth is performed using halide vapor phase epitaxy, with a temperature of 400–1200°C, a growth pressure of 10–500 Torr, an HCl flow rate of 10–150 sccm, an oxygen flow rate of 100–5000 sccm, a carrier gas flow rate of 100–5000 sccm, and a growth time of 0.5–48 h.

9. The method according to claim 1, characterized in that, The gallium oxide epitaxial growth is performed using metal-organic vapor phase epitaxy (MOV), with a temperature of 400–1200 °C, a pressure of 5–100 mbar, a trimethylgallium flow rate of 5–150 sccm, an oxygen flow rate of 100–10000 sccm, and a time of 0.5–48 h.

10. The method according to claim 1, characterized in that, The gallium oxide epitaxial growth is performed using molecular beam epitaxy, with a temperature of 400–1200 °C and a Ga beam equivalent pressure of 1 × 10⁻⁶. -7 ~1×10 -6 mbar, oxygen plasma flow rate of 0.5–4 sccm, oxygen plasma power of 300 W, and duration of 0.5–48 h.

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