Method for growing gallium oxide-doped thin film on magnesium oxide substrate and photoelectric detector

Abstract

The invention provides a method for growing a gallium oxide-doped thin film on a magnesium oxide substrate and a photoelectric detector. The invention discloses a method for growing a doped gallium oxide film on a magnesium oxide substrate. The method comprises the following steps: growing a gallium oxide film on the magnesium oxide substrate; and carrying out annealing treatment on the magnesium oxide substrate and the gallium oxide thin film, so that the magnesium element is diffused into the gallium oxide thin film from the magnesium oxide substrate to obtain the doped gallium oxide thin film.

Description

Technical Field

[0001] The present invention relates to the field of thin films, and in particular, to a method for growing doped gallium oxide thin films on a magnesium oxide substrate and a photodetector. Background Art

[0002] Gallium oxide (Ga2O3) is a semiconductor material with an ultra-wide bandgap, whose bandgap is about 4.8 - 5.2 eV, and the theoretical critical breakdown field strength is about 8 MV / cm; the above properties make it have excellent performance in the field of high-voltage (about greater than 1000 V) and high-power (several kilowatts and above) electronic devices. Gallium oxide is also considered an ideal candidate material for photodetectors (such as ultraviolet or X-ray photodetectors).

[0003] When doping gallium oxide thin films according to the current doping methods, more lattice defects are generated.

[0004] Therefore, a new method for growing doped gallium oxide thin films is needed to improve the above problems. Summary of the Invention

[0005] In view of this, the present invention provides a method for growing doped gallium oxide thin films on a magnesium oxide substrate and a photodetector, in an attempt to solve or at least alleviate at least one of the above problems.

[0006] According to one aspect of the present invention, there is provided a method for growing doped gallium oxide thin films on a magnesium oxide substrate, including: growing a gallium oxide thin film on the magnesium oxide substrate; annealing the magnesium oxide substrate and the gallium oxide thin film so that magnesium elements diffuse from the magnesium oxide substrate into the gallium oxide thin film to obtain a doped gallium oxide thin film.

[0007] Optionally, in the method according to the present invention, the step of growing a gallium oxide thin film on the magnesium oxide substrate includes: growing a gallium oxide thin film on the magnesium oxide substrate by metalorganic chemical vapor deposition.

[0008] Optionally, in the method according to the present invention, when growing a gallium oxide thin film on the magnesium oxide substrate, the growth temperature is 500 - 900 °C, and the chamber pressure is 10 - 200 Torr.

[0009] Optionally, in the method according to the present invention, when growing a gallium oxide thin film on the magnesium oxide substrate, the gallium source flow rate is 10 - 300 sccm, and the oxygen source flow rate is 200 - 5000 sccm.

[0010] Optionally, in the method according to the present invention, when annealing the magnesium oxide substrate and the gallium oxide thin film, the annealing temperature is 800 - 1100 °C, and the annealing time is 1 - 20 min.

[0011] Optionally, in the method according to the present invention, it further includes: before growing the gallium oxide thin film, performing in-situ annealing treatment on the magnesium oxide substrate.

[0012] Optionally, in the method according to the present invention, when performing in-situ annealing treatment on the magnesium oxide substrate, the annealing temperature is 700 - 1100 °C, and the annealing time is 0.5 - 2 h.

[0013] Optionally, in the method according to the present invention, the thickness of the gallium oxide thin film is 1 - 2000 nm.

[0014] Optionally, in the method according to the present invention, it further includes: obtaining the magnesium oxide substrate according to at least one of the following steps: cleaning the initial magnesium oxide substrate with an organic solvent; performing oxygen plasma treatment on the initial magnesium oxide substrate; using nitrogen to blow away the dust on the initial magnesium oxide substrate.

[0015] According to a second aspect of the present invention, there is provided a photodetector, including: a magnesium oxide substrate; a doped gallium oxide thin film on the magnesium oxide substrate; and a metal electrode disposed on the surface of the doped gallium oxide thin film.

[0016] In the method for growing a doped gallium oxide thin film on a magnesium oxide substrate according to the present invention, by using the magnesium oxide substrate, not only is the magnesium oxide substrate doped with the target doping element used as the only impurity source, but also the lattice mismatch degree between the substrate and the gallium oxide thin film can be reduced. Subsequently, annealing treatment is performed on the magnesium oxide substrate and the gallium oxide thin film, and through the annealing process, magnesium elements are controlled to diffuse upward from the magnesium oxide substrate and be doped into the gallium oxide thin film, while also avoiding the damage to the lattice caused by the ion implantation method.

[0017] Furthermore, since the thin film grown according to the present invention has few lattice defects and a low background carrier concentration, the dark current of the photodetector prepared from the doped gallium oxide thin film is small, the response is fast, and the performance is high. Description of the Drawings

[0018] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features, and advantages of the present invention will become clearer. In the drawings:

[0019] Figure 1 A schematic diagram of a method 100 for growing a doped gallium oxide thin film on a magnesium oxide substrate according to an embodiment of the present invention is shown;

[0020] Figure 2 A schematic diagram of diffusion doping of a gallium oxide thin film according to an embodiment of the present invention is shown;

[0021] Figure 3a 、 Figure 3b 、 Figure 3c and Figure 3dSchematic diagrams showing scanning electron microscope images of a first sample, a second sample, a third sample, and a fourth sample respectively;

[0022] Figure 4 Schematic diagram showing a secondary ion mass spectrum of a gallium oxide thin film according to an embodiment of the present invention;

[0023] Figure 5 Schematic diagram showing a photodetector according to an embodiment of the present invention. Detailed implementation manners

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0025] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] In cases where expressions similar to "at least one of A, B, and C, etc." are used, generally, it should be interpreted according to the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0028] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0029] In the context of the present disclosure, when a layer / component is referred to as being "on" another layer / component, the layer / component can be directly on the other layer / component, or there can be an intermediate layer / component between them. Additionally, if a layer / component is "on" another layer / component in one orientation, then when the orientation is reversed, the layer / component can be "under" the other layer / component.

[0030] Five crystal phases of gallium oxide materials have been discovered, including α, β, γ, δ, and ε; among them, the monoclinic β-phase Ga2O3 is the most stable. The β-Ga2O3 material has shown intrinsic n-type conductivity when undoped; intrinsic defects such as oxygen vacancies or gallium interstitials are easily formed in its lattice structure, so problems such as large dark current and obvious persistent photoconductivity effect occur. Large dark current refers to the phenomenon that the background current generated under dark conditions significantly exceeds the normal level. The reasons for large dark current include: lattice defects or impurities inside the semiconductor provide donor energy levels and ionize a large number of free electrons at room temperature, increasing the dark current. The persistent photoconductivity effect refers to the physical phenomenon that the conductivity or photocurrent of the material can still remain at a high level for a long time after the light illumination stops. The possible reasons for the persistent photoconductivity effect include carrier traps caused by crystal defects and impurity atoms, which prolong the lifetime of non-equilibrium carriers.

[0031] To solve problems such as large dark current and obvious persistent photoconductivity effect, it is necessary to select appropriate acceptor impurities for compensating doping of gallium oxide materials. One doping method is to dope by ion implantation; this method of implanting specific dopants will cause damage to the gallium oxide crystal, resulting in more lattice defects, and thus the performance of the photodetector prepared with this thin film is poor.

[0032] Therefore, the present invention proposes a method for growing doped gallium oxide thin films on a magnesium oxide substrate. The magnesium oxide substrate not only serves as the substrate for the gallium oxide thin film but also serves as the only magnesium source for doping the gallium oxide thin film.

[0033] Figure 1 FIG. shows a schematic diagram of a method 100 for growing doped gallium oxide thin films on a magnesium oxide substrate according to an embodiment of the present invention. As Figure 1 shown, method 100 starts at step 110, growing a gallium oxide thin film on a magnesium oxide substrate.

[0034] According to one embodiment, the magnesium oxide substrate is obtained from an initial magnesium oxide substrate. The initial magnesium oxide substrate is a magnesium oxide substrate that has not been cleaned or dried, and the magnesium oxide substrate can be obtained according to at least one of the following steps: cleaning the initial magnesium oxide substrate with an organic solvent; performing oxygen plasma treatment on the initial magnesium oxide substrate; using nitrogen to blow off the floating dust on the initial magnesium oxide substrate. The specific steps for treating the initial magnesium oxide substrate in the present invention are not limited, and one or more of the above steps can be used for treatment. For example, first perform organic solvent cleaning, then perform oxygen plasma treatment, and finally dry with nitrogen.

[0035] According to one embodiment, when performing organic solvent cleaning, the organic solvent may include at least one of polar solvents such as acetone (CH3COCH3) and ethanol (C2H5OH), and non-polar solvents such as n-heptane (C7H 16 ) and the like. The cleaning time for each organic solvent can be more than 5 minutes.

[0036] According to an embodiment of the present invention, when performing organic solvent cleaning, acetone and ethanol are used for cleaning in sequence. The specific cleaning method in the present invention is not limited. For example, ultrasonic cleaning with acetone for 10 minutes, then ultrasonic cleaning with ethanol for 10 minutes; finally, dry with nitrogen.

[0037] According to one embodiment, when performing oxygen plasma treatment on the initial magnesium oxide substrate, the oxygen pressure is 1×10 -5 -5×10 -5 mbar, the oxygen radio frequency power is 230 - 300 W, and the treatment time is 30 - 90 minutes. Oxygen plasma treatment is a technology that generates high-energy active particles by ionizing oxygen to physically etch and chemically modify the material surface. Its core principle is to utilize the active components such as electrons, ions, and free radicals in the plasma to interact with the material surface to achieve goals such as surface modification, cleaning, and hydrophilicity.

[0038] According to an embodiment of the present invention, for the magnesium oxide material used as the substrate in the present invention, crystal orientations such as <100>, <110>, and <111> can be used as the crystal orientation of the substrate surface.

[0039] According to an embodiment of the present invention, gallium oxide thin films are grown on the magnesium oxide substrate by metalorganic chemical vapor deposition (MOCVD).

[0040] According to an embodiment of the present invention, before growing the gallium oxide thin film, in-situ annealing treatment is performed on the magnesium oxide substrate. In-situ annealing treatment refers to performing annealing treatment in the reaction chamber without moving the material when applying metalorganic chemical vapor deposition, to avoid possible contamination or structural changes during sample transfer.

[0041] According to one embodiment, when performing in-situ annealing treatment on a magnesium oxide substrate, the annealing temperature is 700 - 1100 °C, and the annealing time is 0.5 - 2 h. When performing in-situ annealing treatment on a magnesium oxide substrate, it can be carried out in a vacuum environment or in a gas atmosphere, including any one of air, nitrogen, or oxygen. The in-situ annealing treatment is both to remove the remaining organic pollutants and impurities such as magnesium carbonate and magnesium hydroxide on the substrate surface, and also to repair the surface morphology and obtain a substrate surface with low roughness.

[0042] According to an embodiment of the present invention, when performing in-situ annealing treatment on a magnesium oxide substrate, in an oxygen-containing gas atmosphere, the annealing temperature is 800 - 1000 °C, and the in-situ annealing time is 0.5 - 2 h.

[0043] According to an embodiment of the present invention, when performing in-situ annealing treatment on a magnesium oxide substrate, in an oxygen gas atmosphere, the annealing temperature is 850 °C, the oxygen flow rate is 500 sccm, and the in-situ annealing time is 1 h.

[0044] According to one embodiment, when epitaxially growing a gallium oxide thin film by MOCVD, the growth temperature is 500 - 900 °C, and the chamber pressure is 10 - 200 Torr. The chamber pressure is the growth pressure of the gallium oxide thin film in the reaction chamber.

[0045] According to an embodiment of the present invention, when epitaxially growing a gallium oxide thin film by MOCVD, the growth temperature is 720 °C, and the chamber pressure is 60 Torr.

[0046] According to one embodiment, when epitaxially growing a gallium oxide thin film by MOCVD, the gallium source flow rate is 10 - 300 sccm, and the oxygen source flow rate is 200 - 5000 sccm.

[0047] According to one embodiment, when epitaxially growing a gallium oxide thin film by MOCVD, the gallium source used includes trimethylgallium ((CH3)3Ga) or triethylgallium (Ga(C2H5)3); the oxygen source used includes at least one of oxygen, ozone, nitric oxide, nitrogen dioxide, dinitrogen monoxide, and oxygen plasma.

[0048] According to an embodiment of the present invention, when epitaxially growing a gallium oxide thin film by MOCVD, triethylgallium is used as the gallium source, and the corresponding carrier gas is argon with a flow rate of 1000 sccm; oxygen is used as the oxygen source with a flow rate of 1000 sccm. The present invention does not limit the specific gallium source and gallium source flow rate, oxygen source and oxygen source flow rate used; the specific parameters can be set according to the phase, composition stoichiometric ratio, etc. of the desired gallium oxide material to be grown.

[0049] According to an embodiment of the present invention, when epitaxially growing a gallium oxide thin film by MOCVD, the rotation speed of the susceptor can be set to 60 rpm.

[0050] According to an embodiment of the present invention, when epitaxially growing a gallium oxide thin film by MOCVD, the growth time of the gallium oxide thin film can be set to 20 min.

[0051] According to an embodiment, the thickness of the gallium oxide thin film grown on the substrate can be achieved to be 1 - 2000 nm.

[0052] According to an embodiment of the present invention, the thickness of the gallium oxide thin film grown on the substrate can be achieved to be 200 nm.

[0053] According to an embodiment of the present invention, the gallium oxide thin film grown on the substrate is β-phase gallium oxide.

[0054] Subsequently, step 120 is performed to anneal the magnesium oxide substrate and the gallium oxide thin film so that magnesium elements diffuse from the magnesium oxide substrate into the gallium oxide thin film to obtain a doped gallium oxide thin film.

[0055] The current substrates in use (such as sapphire substrates) have a relatively high lattice mismatch with the gallium oxide thin film. Therefore, the present invention proposes a method for growing a doped gallium oxide thin film on a magnesium oxide substrate. The magnesium oxide substrate not only serves as the substrate for the gallium oxide thin film but also serves as the only magnesium source for doping the gallium oxide thin film.

[0056] The magnesium oxide substrate has a cubic crystal structure and has a relatively small lattice mismatch with the gallium oxide crystal. The lattice mismatch is used to quantify the degree of difference in lattice constants between two materials. The lattice mismatch affects the epitaxial growth of crystals, will generate a large number of defects in the epitaxial layer, and even make it impossible to grow single crystals, affecting the performance and lifespan of the device.

[0057] The magnesium ions in the magnesium oxide substrate are relatively active at high temperatures, enabling the substrate to also serve as a magnesium source and realizing the bottom-up thermal diffusion doping of the gallium oxide thin film only through the annealing step after film formation. Therefore, in the method for growing a doped gallium oxide thin film according to this embodiment, using the magnesium oxide substrate not only serves as the only impurity source but also can reduce the lattice mismatch between the substrate and the gallium oxide thin film.

[0058] Furthermore, since the method of the present invention does not affect the film growth process, the lattice defects caused are smaller compared to the doping method using dopants during the film growth process, and it also avoids the damage to the lattice caused by the ion implantation method. The method of the present invention provides a reference solution for preparing gallium oxide thin films with low background carrier concentration, even p-type gallium oxide thin films and high-performance gallium oxide photodetectors.

[0059] Since the doped gallium oxide thin film grown by the present invention can achieve effective acceptor doping and has undergone an annealing treatment, the film quality is relatively high, so its background carrier concentration is low, which also indicates better device performance.

[0060] According to one embodiment, when annealing the magnesium oxide substrate and the gallium oxide thin film, the annealing temperature is generally higher than the growth temperature of the gallium oxide thin film. The annealing temperature is 800 - 1100 °C, and the annealing time is 1 - 20 min. Under such annealing conditions, the upward diffusion of magnesium ions and the uniform distribution of magnesium ions in the gallium oxide thin film can be promoted, and a doped gallium oxide thin film with relatively high quality can be obtained.

[0061] According to an embodiment of the present invention, when annealing the magnesium oxide substrate and the gallium oxide thin film, the annealing temperature is 800 °C and the annealing time is 3 - 5 min.

[0062] According to another embodiment of the present invention, in an RTP (Rapid Thermal Processing) device, the annealing temperature is set to 900 °C, and the magnesium oxide substrate and the gallium oxide thin film are annealed for 5 min in an oxygen atmosphere to obtain a doped gallium oxide thin film. The RTP device can be specifically implemented as a rapid annealing furnace; the grown doped gallium oxide thin film can be specifically implemented as a magnesium-doped gallium oxide thin film.

[0063] According to one embodiment, when annealing the magnesium oxide substrate and the gallium oxide thin film, a suitable gas atmosphere is used to promote the upward doping of magnesium ions from the substrate and their uniform distribution in the doped gallium oxide thin film. When annealing the magnesium oxide substrate and the gallium oxide thin film, it can be carried out in a vacuum environment or using a gas atmosphere including one of air, nitrogen, and oxygen.

[0064] Figure 2 Shows a schematic diagram of diffusion doping of a gallium oxide thin film according to an embodiment of the present invention. As Figure 2 shown, when annealing the magnesium oxide substrate 210 and the gallium oxide thin film 220, the magnesium ions 211 in the magnesium oxide substrate 210 diffuse from bottom to top and dope into the gallium oxide thin film 220 along the direction indicated by the arrow. During the film growth process, a small part of the magnesium ions in the substrate will diffuse into the gallium oxide thin film 220, but the doping amount in this process cannot meet the predetermined requirements. Therefore, subsequent annealing steps are needed to further promote the upward diffusion of magnesium ions 211 and their uniform distribution in the gallium oxide thin film 220. This method has simple and stable process, little damage to the crystal, low cost, and does not require an external magnesium source.

[0065] According to one embodiment, the epitaxial relationship between the gallium oxide thin film and the magnesium oxide substrate is β-Ga2O3<100> / / MgO<100>, indicating that the <100> crystal orientation of the β-phase gallium oxide crystal is parallel to the <100> crystal orientation of the magnesium oxide crystal.

[0066] According to an embodiment of the present invention, when annealing the magnesium oxide substrate and the gallium oxide thin film, with other annealing parameters being the same, the annealing times of four samples are set to 0, 1 min, 5 min, and 10 min respectively to obtain four samples E0, E1, E5, and E10. Other identical parameters during the annealing process include: the atmosphere used is oxygen, and the annealing temperature is 900 degrees Celsius. Figure 3a A schematic diagram showing a scanning electron microscope (SEM) image of the first sample (sample E0); Figure 3b A schematic diagram showing a scanning electron microscope image of the second sample (sample E1); Figure 3c A schematic diagram showing a scanning electron microscope image of the third sample (sample E5); Figure 3d A schematic diagram showing a scanning electron microscope image of the fourth sample (sample E10). It can be Figure 3a - Figure 3d seen that the annealing treatment causes changes in the surface morphology of the gallium oxide thin film.

[0067] Figure 4 A schematic diagram showing a secondary ion mass spectrum of the gallium oxide thin film according to an embodiment of the present invention. As Figure 4 shown, the two samples being compared are the first sample (sample E0) and the third sample (sample E5) respectively. The abscissa is the depth, unit: nanometer. The depth range of the sample is the gallium oxide thin film from about 0 to 190 nm, and the magnesium oxide substrate in the depth range greater than 190 nm. The ordinate is the secondary ion yield. The secondary ion yield is the average number of secondary ions generated by a primary ion hitting the sample surface.

[0068] It can be seen from the Mg curve in the depth range of about 0 to 190 nm that the magnesium doping concentration of the third sample (sample E5) is about twice that of the first sample (sample E0), and it is uniformly distributed longitudinally in the gallium oxide thin film, verifying the feasibility of doping the gallium oxide thin film through the magnesium oxide substrate in the present invention.

[0069] According to an embodiment of the present invention, the present invention also prepares a photodetector based on the prepared doped gallium oxide thin film. Figure 5 A schematic diagram showing a photodetector according to an embodiment of the present invention. As Figure 5As shown, the photodetector includes a gallium oxide substrate 210, a doped gallium oxide thin film 220 on a magnesium oxide substrate, and a metal electrode disposed on the surface of the doped gallium oxide thin film.

[0070] The doped gallium oxide thin film 220 is prepared according to the method 100 for growing a doped gallium oxide thin film on a magnesium oxide substrate according to an embodiment of the present invention. Since the thin film lattice defects of the gallium oxide thin film prepared by the present invention are few and the background carrier concentration is low, the dark current of the photodetector prepared according to the doped gallium oxide thin film is small, the response is fast, and the performance is relatively high. Figure 5 The metal electrode shown is an interdigital electrode 230. Figure 5 The implementation manner of the metal electrode shown is only exemplary, and the present invention does not limit the specific implementation manner of the metal electrode.

[0071] According to one embodiment, the metal electrode disposed on the doped gallium oxide thin film can be specifically implemented as at least one of a Ti / Au structure, a Ti / Al / Ni / Au structure, a Cr / Au structure, Ag, In, Al, indium tin oxide (ITO), a Ni / Au structure, Pt, PtO, Au, or graphene. The metal electrode can be prepared by an electron beam evaporation or magnetron sputtering process.

[0072] According to one embodiment, the metal electrode can be specifically implemented as at least one of a square electrode, a circular electrode, an interdigital electrode, or a polygonal electrode.

[0073] According to an embodiment of the present invention, the metal electrode is a Ti / Al / Ni / Au structure from bottom to top, that is, the metal electrode is Ti, Al, Ni, and Au in sequence from bottom to top. Among them, the thicknesses of Ti, Al, Ni, and Au are 20 nm, 100 nm, 60 nm, and 80 nm respectively. To promote the ohmic contact between the metal electrode and the doped gallium oxide thin film, in the photolithography process, after the photoresist is peeled off, the photodetector is annealed in a nitrogen atmosphere at a temperature of 470 °C for 1 min to obtain the final device.

[0074] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagram may represent a module. It should also be noted that in some alternative implementations, the functions noted in the blocks may occur in a different order than that noted in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram or flowchart, and combinations of blocks in the block diagram or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions. Those skilled in the art will appreciate that the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present disclosure.

[0075] The embodiments of the present disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments have been described separately above, this does not mean that the measures in the respective embodiments cannot be used advantageously in combination. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present disclosure.

[0076] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments and / or claims of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0077] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in the respective embodiments cannot be used advantageously in combination. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present invention.

Claims

1. A method for growing doped gallium oxide thin film on a magnesium oxide substrate, comprising: Growing a gallium oxide thin film on a magnesium oxide substrate; Annealing the magnesium oxide substrate and the gallium oxide thin film so that magnesium element diffuses from the magnesium oxide substrate into the gallium oxide thin film to obtain a doped gallium oxide thin film.

2. The method according to claim 1, wherein Growing a gallium oxide thin film on a magnesium oxide substrate includes: Growing a gallium oxide thin film on the magnesium oxide substrate by metalorganic chemical vapor deposition.

3. The method according to claim 2, wherein, When growing a gallium oxide thin film on the magnesium oxide substrate, the growth temperature is 500 - 900 °C, and the chamber pressure is 10 - 200 Torr.

4. The method according to claim 2 or 3, wherein When growing a gallium oxide thin film on the magnesium oxide substrate, the flow rate of the gallium source is 10 - 300 sccm, and the flow rate of the oxygen source is 200 - 5000 sccm.

5. The method according to any one of claims 1-3, wherein When annealing the magnesium oxide substrate and the gallium oxide thin film, the annealing temperature is 800 - 1100 °C, and the annealing time is 1 - 20 min.

6. The method according to claim 2, further comprising: Before growing the gallium oxide thin film, in-situ annealing treatment is performed on the magnesium oxide substrate.

7. The method according to claim 6, wherein, When performing in-situ annealing treatment on the magnesium oxide substrate, the annealing temperature is 700 - 1100 °C, and the annealing time is 0.5 - 2 h.

8. The method according to any one of claims 1 to 3, wherein, The thickness of the gallium oxide thin film is 1 - 2000 nm.

9. The method according to any one of claims 1 - 3, further comprising: Obtaining a magnesium oxide substrate according to at least one of the following steps: Cleaning the initial magnesium oxide substrate with an organic solvent; Performing oxygen plasma treatment on the initial magnesium oxide substrate; Using nitrogen to blow off the dust on the initial magnesium oxide substrate.

10. A photodetector, comprising: A magnesium oxide substrate; A doped gallium oxide thin film on the magnesium oxide substrate, the doped gallium oxide thin film being prepared according to the method for growing doped gallium oxide thin film on a magnesium oxide substrate according to any one of claims 1 - 9; A metal electrode disposed on the surface of the doped gallium oxide thin film.

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