P-type gallium oxide thin film and preparation method and application thereof

Abstract

The invention belongs to the technical field of ultra-wide bandgap semiconductor materials and devices, and particularly discloses a P-type gallium oxide thin film and a preparation method and application thereof. In the Ar atmosphere, the gallium oxide thin film doped with Bi and Cu elements is formed on the surface of the substrate by using a radio frequency magnetron sputtering device, and a new valence band is formed in a forbidden band by using Bi6S and O2p orbital hybridization, so that the width of the forbidden band is reduced, the self-sinking energy of holes is reduced, the Hall hole doping concentration of the formed Ga2O3 thin film is improved, and the performance of the thin film is improved. And thus, the prepared Ga2O3 film forms P-type conduction.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-wide bandgap semiconductor materials and devices, and in particular to a P-type gallium oxide film and a preparation method and application thereof. Background Art

[0002] With the development of the fourth generation of ultra-wide bandgap semiconductors, it has broad application prospects in many fields such as 5G communications, artificial intelligence, automotive electronics, and cloud computing. β-Ga2O3, as a representative of them, has a high bandgap width (~4.9ev), a high breakdown field strength (8MV·cm -1 ), excellent thermal stability, chemical stability and high visible light and infrared transmittance. The above characteristics make β-Ga2O3 widely used in high-power electronic devices, solar-blind ultraviolet detectors, transparent electrodes, gas sensors and other fields.

[0003] At present, great progress has been made in the epitaxial growth and n-type doping of β-Ga2O3 thin films. Since it is inevitable to introduce defect states such as oxygen vacancies (VO), gallium vacancies (VGa) and gallium interstitials (Gai) during the preparation of actual β-Ga2O3 materials, the actually grown β-Ga2O3 usually exhibits n-type conductive properties. Due to factors such as the flat valence band, large effective mass, easy formation of self-trapped holes, and the self-compensation effect of unintentional doping donor defects of β-Ga2O3, it is very difficult to obtain p-type doped β-Ga2O3. In order to realize the large-scale application of gallium oxide thin films, p-type doping is a problem that must be solved. Summary of the invention

[0004] The purpose of the present invention is to provide a P-type gallium oxide film and a preparation method and application thereof, so as to solve the problem that p-type doped β-Ga2O3 is difficult to obtain at present.

[0005] In order to achieve the above object, the specific technical solution adopted by the present invention is as follows:

[0006] In the first aspect, the present invention provides a method for preparing a p-type gallium oxide film, which is to form a gallium oxide film doped with Bi and Cu elements on the surface of a substrate by radio frequency magnetron sputtering in an Ar atmosphere. The Bi element easily replaces the Ga(II) position of the β-Ga2O3 octahedron. Since the hybridization of Bi6S and O2p orbitals forms a new valence band in the forbidden band, the band gap width is reduced, and the incorporation of the Bi element reduces the self-trapping energy of holes; and the simultaneous incorporation of the Cu element decouples the valence band maximum of the Bi-doped gallium oxide, so the energy levels of the host VBM and the defect state can be adjusted independently and flexibly, so that the acceptor energy level is close enough to the VBM of the host material, so the co-doping of Bi and Cu is a potential way to achieve p-type doping.

[0007] More specifically, the method for preparing the P-type gallium oxide thin film comprises the following steps:

[0008] S1. Prepare a target and a substrate, wherein the target composition is Ga2O3+x%Bi2O3+y%CuO, wherein 0<x<5, 0<y<10;

[0009] S2. Using a radio frequency magnetron sputtering device, sputtering the target material onto the substrate to generate a Bi and Cu element doped gallium oxide layer;

[0010] S3. Annealing the sample obtained in step S2 to obtain a p-type gallium oxide thin film.

[0011] Furthermore, in step S1, the substrate is a single-polished sapphire substrate with a (0001) plane.

[0012] Furthermore, in step S2, before magnetron sputtering, the substrate is ultrasonically cleaned using acetone, ethanol, and deionized water in sequence to remove surface impurities.

[0013] Furthermore, in step S2, the magnetron sputtering method is as follows: first, the reaction furnace is evacuated, and then argon gas is introduced, and the sputtering power is adjusted to 415-425W, and the sputtering time is 55-65min. More preferably, the sputtering power is adjusted to 420W, and the sputtering time is 60min.

[0014] Furthermore, in step S3, annealing is performed in a tube furnace, the annealing environment is an O2 atmosphere, the annealing temperature is 845-855°C, and the annealing time is 0.9-1.1 hours. More preferably, the annealing temperature is 850°C, and the annealing time is 1 hour.

[0015] In a second aspect, the present invention provides a bismuth- and copper-doped P-type gallium oxide thin film prepared according to the above preparation method.

[0016] In a third aspect, the present invention provides the application of the bismuth and copper element doped P-type gallium oxide thin film prepared by the above preparation method in the field of ultra-wide bandgap semiconductor devices.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The method for preparing a p-type gallium oxide film of the present invention sputters Ga2O3+x%2O3+y%CuO target material in a vacuum chamber by radio frequency magnetron sputtering, and obtains a p-type conductive Bi and Cu doped Ga2O3 film by adjusting the radio frequency magnetron sputtering power. The technical solution replaces the Ga(II) position of the β-Ga2O3 octahedron by Bi and Cu elements, thereby realizing a p-type conductive gallium oxide film; the Bi and Cu doped p-type gallium oxide film prepared by the method of the present invention is a high-quality epitaxial film with high hole carrier concentration, low resistivity, good p-type conductive stability, and simple equipment and preparation process required, and low production cost, which will promote the application of gallium oxide in the field of ultra-wide bandgap semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the X-ray diffraction (XRD) spectrum of the P-type gallium oxide thin film obtained in Example 1 of the present invention.

[0020] Figure 2 This is a transmission spectrum diagram of the P-type gallium oxide thin film obtained in Example 1 of the present invention.

[0021] Figure 3 This is a graph of the bandgap width of the P-type gallium oxide film obtained in Example 1 of the present invention.

[0022] Figure 4 This is a Raman spectrum of the P-type gallium oxide thin film obtained in Example 1 of the present invention.

[0023] Figure 5 Schematic diagram of vacuum temperature-variable Hall test results of P-type gallium oxide thin film according to Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] A P-type gallium oxide thin film is prepared according to the following method:

[0027] S1. Prepare a target and a substrate, wherein the target is a gallium oxide ceramic block target doped with 5% Bi and 1% Cu, and the substrate is a single-polished sapphire substrate with a (0001) surface;

[0028] S2. The substrate is ultrasonically cleaned with acetone, ethanol, and deionized water in sequence to remove surface impurities; after nitrogen drying, the target material is sputtered onto the substrate using a radio frequency magnetron sputtering device: the reactor is first evacuated, and then argon gas with a purity of 99.9% is introduced, the Ar flow rate is maintained at 10sccm, the substrate temperature is fixed at room temperature, the sputtering power is adjusted to 420W, the sputtering time is 60min, and a Bi and Cu element-doped gallium oxide layer is generated;

[0029] S3. Anneal the sample obtained in step S2 in a tube furnace in an O2 atmosphere at a temperature of 850° C. for 1 h to obtain a p-type gallium oxide thin film.

[0030] The p-type gallium oxide film prepared in Example 1 was tested for performance, and the test results are as follows:

[0031] Figure 1 The XRD pattern of Bi- and Cu-doped β-Ga2O3 films. After annealing, polycrystalline β-Ga2O3 films were obtained, showing the characteristics of high-quality monoclinic structure. The three main peaks at 19.0, 38.6 and 59.2° are consistent with (-201), (-402) and (-603) of β-Ga2O3, respectively. This is because the monoclinic (-201) crystal plane family is compatible with the lattice of the c-sapphire surface, and the film will grow along the (-201) plane.

[0032] Figure 2 This is the transmission spectrum of P-type gallium oxide. The transmittance of the film in the visible light range is greater than 70%, which indicates that the sample has good transmittance.

[0033] Figure 3 is the bandgap diagram of P-type gallium oxide film. The optical bandgap of the film can be approximated by the absorption spectrum. The specific relationship is:

[0034] (αhν) n =B(hν-Eg)

[0035] Where B is a constant related to the material, hν is the incident photon energy, α is the absorption rate, direct bandgap semiconductor n = 2, indirect bandgap semiconductor n = 1 / 2, Ga2O3 is a direct bandgap semiconductor. 2 When the vertical axis is 0.0400 W and the horizontal axis is 0.0200 W, the band gap is reduced to 3.80 eV.

[0036] Figure 4 This is the Raman spectrum of P-type gallium oxide film. The Raman characteristic peak signal of the sample is very strong, indicating that the crystal quality is very high. 750cm -1 A g (7) The peak is a typical Raman spectral feature of Ga2O3 and is generally attributed to the high-frequency stretching and bending of GaO4 tetrahedron.

[0037] Figure 5It is a schematic diagram of the vacuum variable temperature Hall test results of P-type gallium oxide film. When the field strength is 1000G, the Hall conductivity type of the sample sputtered at 420W is P-type, indicating that the present invention successfully prepares P-type gallium oxide samples.

[0038] This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention will be protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing a P-type gallium oxide thin film, characterized in that: In an Ar atmosphere, a gallium oxide film doped with Bi and Cu elements is formed on the surface of a substrate by using a radio frequency magnetron sputtering method.

2. The method for preparing a P-type gallium oxide thin film according to claim 1, characterized in that: The following steps are involved: S1. Prepare a target and a substrate, wherein the target composition is Ga2O3+x%Bi2O3+y%CuO, wherein 0<x<5, 0<y<10; S2. Using a radio frequency magnetron sputtering device, sputtering the target material onto the substrate to generate a Bi and Cu element doped gallium oxide layer; S3. Annealing the sample obtained in step S2 to obtain a p-type gallium oxide thin film.

3. The method for preparing a P-type gallium oxide thin film according to claim 2, characterized in that: In step S1, the substrate is a single-polished sapphire substrate with a (0001) plane.

4. The method for preparing a P-type gallium oxide thin film according to claim 2, characterized in that: In step S2, before magnetron sputtering, the substrate is ultrasonically cleaned using acetone, ethanol, and deionized water in sequence to remove surface impurities.

5. The method for preparing a P-type gallium oxide thin film according to claim 2, characterized in that: In step S2, the magnetron sputtering method is as follows: first, the reaction furnace is evacuated, and then argon gas is introduced, and the sputtering power is adjusted to 415-425W, and the sputtering time is 55-65min.

6. The method for preparing a P-type gallium oxide thin film according to claim 2, characterized in that: In step S3, annealing is performed in a tubular furnace, the annealing environment is an O2 atmosphere, the annealing temperature is 845-855°C, and the annealing time is 0.9-1.1h.

7. A bismuth- and copper-doped P-type gallium oxide thin film obtained by the preparation method according to any one of claims 1 to 6.

8. Application of the bismuth and copper doped P-type gallium oxide film according to claim 7 in the field of ultra-wide bandgap semiconductor devices.

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