A method for van der waals epitaxy of beta phase gallium oxide thin film on hexagonal boron nitride substrate

Abstract

The application relates to a method for van der Waals epitaxy of a beta-phase gallium oxide film on a hexagonal boron nitride substrate, and relates to the field of semiconductor material preparation. The method comprises the following steps: preparing an h-BN film substrate; placing the h-BN film substrate into a downstream area of a double-temperature-zone tubular furnace, placing metallic gallium into an upstream area of the double-temperature-zone tubular furnace, and vacuumizing the tubular furnace to below 2 Pa; introducing argon into a reaction chamber, heating the substrate to a growth temperature; adjusting the argon flow rate, and flushing the tubular furnace for 1 min; heating the metallic gallium to a volatilization temperature, then adjusting the argon flow rate and introducing oxygen, and growing a beta-Ga2O3 film; and cooling down, so as to finally obtain a beta-Ga2O3 film on the h-BN substrate. The application grows beta-Ga2O3 by using the van der Waals epitaxy technology based on the h-BN substrate, so that a high-quality and low-defect-density epitaxial film is obtained, and meanwhile, the two-dimensional h-BN has easy peelability, so that the lossless transfer of the beta-Ga2O3 film can be realized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material preparation, and more particularly to a method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate. Background Technology

[0002] As semiconductor devices demand increasingly higher performance in terms of high voltage resistance, high temperature resistance, and high power, the development and application potential of traditional semiconductor materials are being limited. Third-generation semiconductor materials and ultra-wide bandgap semiconductors, such as diamond and gallium oxide (Ga2O3), have become research hotspots in the field of semiconductor materials and devices. Ga2O3 has five isomers, among which the monoclinic β-phase Ga2O3 (β-Ga2O3) has the most stable phase structure, with a bandgap of approximately 4.6–4.9 eV and an electron mobility of 300 cm⁻¹. 2 With a theoretical breakdown field strength of 8 MV / cm, β-Ga₂O₃ exhibits a high Baliga figure of merit of 3444, which is 10 times that of SiC and 4 times that of GaN, particularly as a power device loss indicator. Furthermore, β-Ga₂O₃ has a cutoff absorption edge at 250 nm and a transmittance exceeding 80% in the visible light range, making it an ideal material for developing solar-blind ultraviolet detectors. Moreover, compared to other wide-bandgap semiconductor materials, β-Ga₂O₃ single-crystal substrates can be achieved using low-cost, high-efficiency high-temperature melt growth techniques. Therefore, β-Ga₂O₃ demonstrates enormous development potential and application value in ultra-high voltage power electronic devices, deep ultraviolet optoelectronic devices, and extreme environment applications.

[0003] High-quality epitaxial thin film materials are the foundation and prerequisite for developing high-performance devices. Currently, while homoepitaxial β-Ga₂O₃ films can achieve good crystal quality, Ga₂O₃ single-crystal substrates are very expensive. Furthermore, due to the low thermal conductivity of Ga₂O₃, power devices based on Ga₂O₃ substrates have poor heat dissipation capabilities, severely impacting device performance and lifespan. Heteroepitaxial Ga₂O₃ films are one method to address these issues; however, due to significant lattice and thermal mismatches between the heteroepitaxial substrate and the epitaxial film, the grown β-Ga₂O₃ films have numerous lattice defects, resulting in quality far inferior to homoepitaxial materials. Therefore, there is an urgent need to find a method for heteroepitaxial high-quality β-Ga₂O₃ films.

[0004] In recent years, van der Waals epitaxy based on two-dimensional layered substrates has been widely used for heteroepitaxial production of high-quality III-V and oxide semiconductor thin films. Graphene and hexagonal boron nitride (h-BN) are commonly used as van der Waals epitaxial substrates. h-BN and β-Ga2O3 both belong to ultra-wide bandgap semiconductor materials, possessing many excellent properties such as atomically flat surfaces and high thermal conductivity. Van der Waals epitaxy of β-Ga2O3 on high thermal conductivity layered h-BN substrates holds promise for obtaining high-quality heteroepitaxial thin films with low defect density, while overcoming the heat dissipation difficulties caused by the low thermal conductivity of β-Ga2O3. However, related research has not yet been reported. Summary of the Invention

[0005] The purpose of this invention is to provide a method for van der Waals epitaxy of β-phase gallium oxide thin films on hexagonal boron nitride substrates. On one hand, epitaxy of β-Ga₂O₃ on a two-dimensional layered h-BN surface is expected to yield high-quality β-Ga₂O₃ epitaxial thin films with low defect density. On the other hand, the easy peeling properties of two-dimensional h-BN enable non-destructive transfer of β-Ga₂O₃ thin films and heterogeneous integration with other high thermal conductivity substrates, providing a solution to the heat dissipation problem of β-Ga₂O₃ devices.

[0006] This invention provides a method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate, the method comprising the following steps:

[0007] Step 1: Prepare an h-BN thin film substrate;

[0008] Step 2: Place the h-BN thin film substrate in the downstream zone of the dual-temperature zone tube furnace, and place the 99.999% pure gallium metal in the upstream zone of the dual-temperature zone tube furnace. The h-BN thin film substrate and the gallium metal are 30-38 cm apart. Evacuate the tube furnace to below 2 Pa.

[0009] Step 3: Introduce argon gas at 50-300 sccm into the reaction chamber and heat the h-BN thin film substrate to the growth temperature;

[0010] Step 4: Adjust the argon flow rate to 1000 sccm and flush the tube furnace for 1 min;

[0011] Step 5: Heat the metallic gallium to a volatilization temperature, then adjust the argon gas to 40-300 sccm and introduce oxygen at 5-20 sccm to grow a β-Ga2O3 thin film for 20-200 min;

[0012] Step 6: Cool down to obtain the β-Ga2O3 thin film on the h-BN substrate.

[0013] Further, in step 1, the h-BN thin film substrate is a 5-10 layer h-BN thin film directly grown or transferred on a dielectric substrate.

[0014] Furthermore, the growth method of the h-BN thin film substrate is a commonly used method in the art, such as chemical vapor deposition or ion beam sputtering deposition, and the transfer method is a commonly used method in the art, such as mechanical peeling, dry transfer, or wet transfer, and the dielectric substrate is a sapphire, SiO2 / Si, or quartz substrate.

[0015] Furthermore, the temperature of the h-BN thin film substrate in step 3 is 650°C to 800°C;

[0016] Furthermore, in step 5, the gallium volatilization temperature is 800°C to 850°C, and the pressure in the tube furnace during the growth of the β-Ga2O3 thin film is 30Pa to 120Pa.

[0017] Beneficial effects:

[0018] As can be seen from the above technical solution, the method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate provided by the present invention has the following beneficial effects:

[0019] (1) The present invention can reduce the dislocations and defects caused by mismatch in the epitaxial film by van der Waals epitaxy of β-Ga2O3 film on the surface of two-dimensional layered h-BN substrate, and obtain high-quality epitaxial film with low defect density.

[0020] (2) Two-dimensional h-BN has easy peelability, which can realize the non-destructive transfer of β-Ga2O3 film and heterogeneous integration with other high thermal conductivity substrates, providing a solution to the heat dissipation problem of β-Ga2O3 devices. Attached Figure Description

[0021] Figure 1 This is a flowchart of the present invention;

[0022] Figure 2 The Raman spectrum of the h-BN thin film substrate;

[0023] Figure 3 The image shows the Raman spectrum of an epitaxial β-Ga2O3 thin film on an h-BN substrate.

[0024] Figure 4 X-ray diffraction patterns of the examples and comparative samples; Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that the implementation methods not illustrated or described herein are forms known to those skilled in the art. In addition, this document may provide examples of parameters containing specific values, but it should be understood that the parameters need not be exactly equal to the corresponding values, but are approximate to the corresponding values ​​within acceptable error tolerances or design constraints.

[0026] In view of this, the present invention provides a method for van der Waals epitaxy of β-phase gallium oxide thin films on hexagonal boron nitride substrates. Figure 1 A flowchart illustrating the method for van der Waals epitaxy of β-phase gallium oxide thin films on hexagonal boron nitride substrates provided by the present invention is shown. Specific embodiments are as follows:

[0027] Step 1: Prepare an h-BN thin film substrate:

[0028] Ten layers of h-BN thin film were directly grown on a dielectric substrate sapphire (006) using ion beam sputtering deposition.

[0029] Figure 2 The image shows the Raman spectrum of an h-BN thin film substrate grown on Sapphire (006) according to an embodiment of the present invention. Figure 2 It can be seen that it is 1363.8cm -1 The presence of sharp h-BN characteristic peaks indicates that the prepared h-BN thin film substrate has good crystal quality.

[0030] Step 2: Place the h-BN thin film substrate in the downstream zone of the dual-temperature zone tube furnace, and place the 99.999% pure gallium metal in the upstream zone of the dual-temperature zone tube furnace. When placing the h-BN thin film substrate and the gallium metal, the distance between them should be 34 cm. Then, evacuate the tube furnace to below 2 Pa.

[0031] Step 3: Introduce 300 sccm of argon gas into the reaction chamber of the tube furnace, while simultaneously heating the substrate to a growth temperature of 800°C.

[0032] Step 4: Adjust the argon flow rate to 1000 sccm and flush the tubular furnace chamber with argon for 1 minute;

[0033] Step 5: Heat the metallic gallium to its volatilization temperature of 840℃, then adjust the argon gas to 50 sccm and introduce oxygen at 10 sccm, maintaining the pressure in the tube furnace at 40 Pa, and grow the β-Ga2O3 thin film for 30 min.

[0034] Step 6: Cool down to obtain the β-Ga2O3 thin film on the h-BN substrate.

[0035] Figure 3The Raman spectrum of a β-Ga2O3 thin film grown on an h-BN substrate according to an embodiment of the present invention is shown. Figure 3 We can see that, apart from Sapphire(006), there are obvious characteristic peaks of β-Ga2O3.

[0036] Comparative Example

[0037] This comparative example follows the steps in the embodiment to perform van der Waals epitaxy of β-Ga2O3 thin films on an h-BN substrate. The only difference from the embodiment is the gallium temperature, which is 780°C. The specific steps are as follows:

[0038] Step 1: Prepare an h-BN thin film substrate:

[0039] Ten layers of h-BN thin film were directly grown on a dielectric substrate Sapphire (006) using ion beam sputtering deposition.

[0040] Step 2: Place the h-BN thin film substrate in the downstream zone of the dual-temperature zone tube furnace, and place the 99.999% pure gallium metal in the upstream zone of the dual-temperature zone tube furnace. When placing the h-BN thin film substrate and the gallium metal, the distance between them should be 34 cm. Then, evacuate the tube furnace to below 2 Pa.

[0041] Step 3: Introduce 300 sccm of argon gas into the reaction chamber of the tube furnace, while simultaneously heating the substrate to a growth temperature of 800°C.

[0042] Step 4: Adjust the argon flow rate to 1000 sccm and flush the tubular furnace chamber with argon for 1 minute;

[0043] Step 5: Heat the metallic gallium to its volatilization temperature of 780℃, then adjust the argon gas to 50 sccm and introduce oxygen at 10 sccm, maintaining the pressure in the tube furnace at 40 Pa, and grow the β-Ga2O3 thin film for 30 min.

[0044] Step 6: Cool down to obtain the sample.

[0045] Figure 4 The X-ray diffraction patterns of the example sample and the comparative sample are shown in the figure. It can be seen from the figure that there is a clear β-Ga2O3 diffraction peak in the example sample, while the comparative sample only has a Sapphire (006) diffraction peak. This indicates that the β-Ga2O3 film epitaxially grown on the h-BN thin film substrate has a (-201) preferred orientation. On the other hand, the β-Ga2O3 film cannot be successfully grown when the temperature of metallic gallium does not reach its volatilization temperature.

[0046] This concludes the description of the method for van der Waals epitaxial β-Ga2O3 thin film on h-BN substrate in this embodiment.

[0047] In summary, the method for van der Waals epitaxial β-Ga2O3 thin films on h-BN substrates of this invention can reduce dislocations and defects caused by mismatch in the epitaxial film, thereby obtaining high-quality β-Ga2O3 epitaxial films with low defect density. Two-dimensional h-BN also possesses easy peeling properties, enabling non-destructive transfer of β-Ga2O3 films and heterogeneous integration with other high thermal conductivity substrates, providing a solution to the heat dissipation problem of β-Ga2O3 devices.

[0048] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate, comprising the following steps: Step 1: Prepare a hexagonal boron nitride (h-BN) thin film substrate; Step 2: Place the h-BN thin film substrate in the downstream zone of the dual-temperature zone tube furnace, and place the 99.999% pure gallium metal in the upstream zone of the dual-temperature zone tube furnace. The h-BN thin film substrate and the gallium metal are 30-38 cm apart. Evacuate the tube furnace to below 2 Pa. Step 3: Introduce argon gas at a flow rate of 50-300 sccm into the reaction chamber and heat the substrate to the growth temperature; Step 4: Adjust the argon flow rate to 1000 sccm and flush the tube furnace for 1 min; Step 5: Heat the metallic gallium to a volatilization temperature, then adjust the argon gas to 40~300 sccm, and introduce oxygen at 5~20 sccm to grow a β-Ga2O3 film for 20~200 min; Step 6: Cool down to obtain the β-Ga2O3 thin film on the h-BN substrate.

2. The method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate according to claim 1, characterized in that, In step 1, the h-BN thin film substrate is a 5-10 layer h-BN thin film grown or transferred directly on a dielectric substrate.

3. The method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate according to claim 2, characterized in that, The h-BN thin film substrate is grown by chemical vapor deposition or ion beam sputtering deposition, and the transfer method is mechanical peeling, dry transfer, or wet transfer. The dielectric substrate is sapphire, SiO2 / Si, or quartz substrate.

4. The method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate according to claim 1, characterized in that, The temperature of the h-BN thin film substrate in step 3 is 650°C to 800°C.

5. The method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate according to claim 1, characterized in that, In step 5, the gallium volatilization temperature is 800°C to 850°C.

6. The method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate according to claim 1, characterized in that, In step 5, the pressure in the tubular furnace during the growth of the β-Ga2O3 thin film is 30 Pa to 120 Pa.

7. The method for van der Waals epitaxial β-phase gallium oxide thin film on a hexagonal boron nitride substrate according to claim 1, characterized in that, The β-Ga2O3 film has a (-201) preferred orientation.

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