Mixed-phase gallium oxide thin film, ultraviolet detector and preparation method

Abstract

The invention relates to the technical field of semiconductor photoelectric detectors, in particular to a mixed-phase gallium oxide thin film, an ultraviolet detector and a preparation method. The preparation method comprises the following steps: sputtering a metal film on the surface of one side of a substrate; after sputtering, the substrate is placed in an MOCVD reaction chamber, and one side of the metal film is tightly attached to a substrate tray; the substrate tray is heated to 710 DEG C to 760 DEG C, and the temperature is maintained for 10 min to 20 min; an oxygen source is introduced into the MOCVD reaction chamber during heating; reducing the temperature of the substrate tray to 650-690 DEG C, and introducing a gallium organic source and an oxygen source at the same time; maintaining for a period of time as required, and epitaxially growing a gallium oxide film with a certain thickness; and after the growth is finished, cooling and taking out to finish the preparation of the mixed-phase gallium oxide film. The method has the advantages that growth of the beta phase is controlled, a small amount of beta-phase gallium oxide is mixed into the alpha-phase gallium oxide thin film, obvious changes of the thin film crystallization quality and the absorption spectral line are not caused, and the high-quality wide-band-gap gallium oxide thin film is obtained; and the falling time of the ultraviolet detector is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor photoelectric detectors, and in particular to a mixed-phase gallium oxide film, an ultraviolet detector and a preparation method thereof. Background Art

[0002] Solar-blind UV photodetectors with a cutoff wavelength below 280 nm have been widely used in various military and civilian applications, such as military flame sensors, missile detection systems, arc sensing, and environmental and biological research. To date, a variety of materials have been explored in the development of solar-blind UV detectors, including SiC, GaN, Ga2O3, MgZnO, and AlGaN. Among them, gallium oxide (Ga2O3) has attracted widespread attention due to its ultra-wide bandgap and large absorption coefficient.

[0003] At present, the research on gallium oxide-based solar-blind UV detectors is mainly focused on β-phase Ga2O3, which is the structure with the highest thermal stability. In recent years, people have become more and more interested in the research of α-Ga2O3, because it has a larger band gap than β-Ga2O3, so it is very suitable for solar-blind UV detection. In addition, α-Ga2O3 has a corundum-like structure, which is the same as the widely used sapphire substrate, so it can be heteroepitaxially grown on a cheap sapphire substrate on a large scale. However, there are still very limited reports on α-Ga2O3 solar-blind UV detectors, and its material quality and the detection performance of UV detectors also need to be further improved and optimized.

[0004] At present, various methods including chemical vapor deposition (CVD), metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE) and halide vapor phase epitaxy (HVPE) have been used to manufacture α-Ga2O3 thin films, but there are few methods for preparing ultraviolet detectors with mixed-phase films mainly based on the α phase. The following are some examples of preparation methods: Method 1. Preparation of mixed-phase gallium oxide MOCVD epitaxy: S1. Using argon as carrier gas, triethylgallium and oxygen as reaction precursors, grow gallium oxide on a substrate to obtain a primary gallium oxide wafer of a first phase mixed with a second phase; S2. Spin-coat ultraviolet photoresist on the primary gallium oxide wafer, and etch an electrode area on the spin-coated ultraviolet photoresist primary gallium oxide wafer; S3. Grow a metal electrode in the electrode area; S4. Remove the ultraviolet photoresist. A solar-blind photodetector is also disclosed; the method uses hydrogen chloride to induce the growth of a gallium oxide film, wherein the solar-blind photodetector uses mixed-phase gallium oxide as a main component, and the mixed-phase gallium oxide of the "embedded" structure has the advantages of low dark current and high responsiveness. In addition, a metal organic chemical vapor deposition method is used to prepare a gallium oxide epitaxial layer, which has the advantages of large-scale production and strong ability to control product quality.

[0005] Method 2. Preparation of α-Ga2O3-based solar-blind ultraviolet detector by magnetron sputtering: (1) Using a-plane sapphire as a substrate for thin film growth, the substrate is ultrasonically cleaned with a cleaning solution in sequence, blown dry with nitrogen, and then immediately placed in a vacuum chamber; (2) Using Ga2O3 ceramic target, a pulsed laser ablation deposition, magnetron sputtering or electron beam evaporation method is used to deposit a (110)-oriented α-Ga2O3 film on the surface of the a-plane sapphire substrate pretreated in step (1); (3) Using a vapor deposition method or a photolithography method, a pair of parallel metal electrodes are prepared on the surface of the (110)-oriented α-Ga2O3 film to obtain the MSM-type α-Ga2O3-based solar-blind ultraviolet detector.

[0006] The method grows a (110) oriented α-Ga2O3 film with good crystal quality on a-plane sapphire. The film has high electron mobility, which makes the device gain large, so the device has a large light-to-dark current ratio and high responsiveness. In addition, the MSM structure of the day-blind ultraviolet detector prepared by the invention has a simple structure and manufacturing process, and the detector prepared by the invention has good detection capability for deep ultraviolet light with a wavelength of 245 nm, and has a small dark current, a large light-to-dark current ratio, a high responsiveness, and stable performance.

[0007] However, the currently used methods for growing α-Ga2O3, such as mist-assisted chemical vapor deposition (Mist-CVD), halide vapor phase epitaxy (HVPE) and magnetron sputtering, are difficult to accurately control the film composition, quality and growth rate, which also restricts the development of α-Ga2O3 day-blind UV detectors. In comparison, metal organic chemical vapor deposition (MOCVD) has the advantages of large-scale production and strong ability to control product quality. Although the addition of other reactants to induce phase change in MOCVD can achieve the control of film crystal form, the introduction of corrosive halides such as HCl will also corrode the substrate and reaction equipment. In addition, the detection wavelength of most UV detectors is concentrated around 250 nm, which is difficult to fully reflect the advantage of α-Ga2O3 wide bandgap compared to β-Ga2O3. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a mixed-phase gallium oxide film, an ultraviolet detector and a preparation method.

[0009] The first object of the present invention is to provide a mixed-phase gallium oxide thin film prepared by the following method: S11: sputtering a metal film on one surface of the substrate; after sputtering, placing the substrate in an MOCVD reaction chamber, with one side of the metal film close to the substrate tray; S12: heating the substrate tray to 710-760° C. and maintaining the temperature for 10-20 min; during the heating period, an oxygen source is introduced into the MOCVD reaction chamber; S13: lowering the temperature of the substrate tray to 650-690° C., while introducing a gallium organic source and an oxygen source; S14: maintaining a period of time according to demand, epitaxially growing a gallium oxide film of a certain thickness; S15: After the growth is completed, the temperature is lowered to room temperature and taken out, thereby completing the preparation of the mixed-phase gallium oxide film on the c-plane sapphire substrate.

[0010] Preferably, the thickness of the mixed-phase gallium oxide film is 80-250 nm, and the band gap is greater than 5.2 eV.

[0011] Preferably, in step S12, the oxygen source flow rate is 100-200 sccm, the main carrier gas flow rate is 500-1000 sccm, and the chamber pressure is maintained at 2000-3000 Pa.

[0012] Preferably, the oxygen source is high-purity oxygen; and the substrate is a double-polished c-plane sapphire substrate.

[0013] Preferably, when heating the substrate tray in step S12, the substrate tray is rotated along the central axis at a speed of 20-100 rpm.

[0014] Preferably, in step S13, the gallium organic source cold trap temperature is 5-10° C., the gallium organic source carrier gas flow rate is 5-10 sccm, the oxygen source flow rate is 200-500 sccm, the main carrier gas flow rate is 1500-3000 sccm, and the chamber pressure is maintained at 1000-2000 Pa.

[0015] The second purpose of the present invention is to provide a mixed-phase gallium oxide ultraviolet detector, which includes, from bottom to top: a substrate, a mixed-phase gallium oxide thin film arranged on the substrate, and an electrode layer arranged on the side of the mixed-phase gallium oxide thin film surface away from the double-polished substrate; a first contact electrode is provided on the positive electrode in the electrode layer, and a second contact electrode is provided on the negative electrode in the electrode layer.

[0016] Preferably, the first contact electrode and the second contact electrode are both gold wire leads.

[0017] Preferably, the electrode layer is an interdigitated electrode with a thickness of 40-80 nm; the interdigitated electrode has an interdigitated width of 10 μm, an interval of 10 μm, and 25 pairs of interdigitated pairs.

[0018] Preferably, it is prepared by the following method: S1: growing mixed-phase gallium oxide thin films on c-plane sapphire substrates; S2: forming an electrode mask on the mixed-phase gallium oxide film by using a photolithography process, sputtering metal by using a coating machine, and removing the photoresist by ultrasonic wave to prepare an electrode layer; S3: Bonding gold wire leads to the positive electrode and the negative electrode of the electrode layer respectively.

[0019] Compared with the prior art, the present invention can achieve the following beneficial effects: The present invention realizes the mixing of a small amount of β-phase gallium oxide in the α-phase gallium oxide film by processing the substrate, adding the β-Ga2O3 pre-reaction process and controlling the growth conditions. The present invention can more accurately control the growth process of the β-phase, so that the β-phase gallium oxide nucleates on the substrate surface, and the mixing of the β-phase does not cause significant changes in the film crystal quality and absorption spectrum, so that a high-quality wide-bandgap gallium oxide film can be obtained, thereby realizing effective detection of shorter wavelength light. In addition, the grain boundaries of the mixed-phase gallium oxide film can accelerate carrier recombination, so that the fall time of the ultraviolet detector is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning electron microscope (SEM) image of the surface of the mixed-phase gallium oxide film provided by an embodiment of the present invention.

[0021] Figure 2 This is an X-ray diffraction pattern of the mixed-phase gallium oxide film provided in an embodiment of the present invention.

[0022] Figure 3 1 is an optical transmittance spectrum of a mixed-phase gallium oxide film provided in an embodiment of the present invention, and the inset is an extrapolated optical band gap of the mixed-phase gallium oxide film.

[0023] Figure 4 It is a schematic diagram of the structure of the ultraviolet detector provided in an embodiment of the present invention.

[0024] Figure 5 It is the time response characteristic curve of the ultraviolet detector provided by the embodiment of the present invention.

[0025] Reference numerals: 1. Substrate; 2. Mixed-phase gallium oxide thin film layer; 3. Interdigitated electrodes; 4. Gold wire leads. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0028] The present invention provides a mixed-phase gallium oxide film, which is mainly composed of α-phase gallium oxide and mixed with a small amount of β-phase gallium oxide, and both the α-phase gallium oxide and the β-phase gallium oxide are in a single orientation; it is specifically prepared by the following method: S11: selecting a double-polished substrate, and sputtering a metal film on one surface of the double-polished substrate; after sputtering, placing the substrate in an MOCVD reaction chamber, with one side of the metal film close to the substrate tray; S12: Use a baking belt to heat the organic source pipeline; rotate the substrate tray along the central axis at a speed of 20-100 rpm to heat the substrate tray to 710-760°C (reaction temperature of β-phase gallium oxide); set the main carrier gas flow rate to 500-1000 sccm, select high-purity oxygen as the oxygen source, the oxygen source flow rate is 100-200 sccm, pass into the reaction chamber, the chamber pressure is 2000-3000 Pa, maintain for 10-20 min, and grow β-phase gallium oxide; during this period, the pusher of the gallium organic source pipeline is 100-500 sccm, and the organic source bottle is in a closed state; S13: lower the temperature of the substrate tray to 650-690°C (α-phase gallium oxide reaction temperature), introduce a gallium organic source and an oxygen source into the reaction chamber at the same time, set the gallium source cold trap temperature to 5-10°C, set the gallium source carrier gas flow rate to 5-10 sccm, the gallium organic source pipeline pusher to 100-200 sccm, the oxygen source flow rate to 200-500 sccm, the main carrier gas flow rate to 1500-3000 sccm, and the chamber pressure to 1000-2000 Pa; S14: Selecting a suitable growth time according to demand, and epitaxially growing a gallium oxide film of a certain thickness; S15: After the growth is completed, the temperature is lowered to room temperature and taken out, thereby completing the preparation of the mixed-phase gallium oxide film on the c-plane sapphire substrate.

[0029] Specifically, in step S14, the epitaxial growth time ranges from 60 to 180 min, and the thickness of the prepared mixed-phase gallium oxide film is 80-250 nm, satisfying the bandgap width greater than 5.2 eV.

[0030] Specifically, in order to further improve the crystal quality of the mixed-phase gallium oxide film during the preparation process, step S15 also includes (performed after taking out the sample): performing thermal annealing treatment for an appropriate time at a certain temperature and atmosphere; the annealing conditions are: annealing treatment for 10-60 min at 500-650°C in an atmosphere of oxygen, nitrogen, argon, air or a mixed gas.

[0031] The present invention also provides an ultraviolet detector, which includes, from bottom to top: a substrate, a mixed-phase gallium oxide thin film arranged on the substrate, and an electrode layer arranged on the side of the mixed-phase gallium oxide thin film surface away from the double-polished substrate; a first contact electrode is provided on the positive electrode in the electrode layer, and a second contact electrode is provided on the negative electrode in the electrode layer.

[0032] Preferably, the electrode layer is an interdigitated electrode with a thickness of 40-80 nm; the interdigitated electrode has an interdigitated width of 10 μm, a spacing of 10 μm, and a pair number of 25. The electrode material is a metal with a high work function, preferably platinum or gold, so as to form a Schottky barrier.

[0033] Preferably, the preparation method comprises the following steps: S1: growing mixed-phase gallium oxide thin films on c-plane sapphire substrates; S2: forming an electrode mask on the mixed-phase gallium oxide film by using a photolithography process, sputtering metal by using a coating machine, and removing the photoresist by ultrasonic wave to prepare an electrode layer; S3: Bonding gold wire leads to the positive electrode and the negative electrode of the electrode layer respectively.

[0034] Specifically, the substrate is a sapphire substrate, including c-plane, a-plane, m-plane, and r-plane sapphire substrates.

[0035] Specifically, the metal film material sputtered on one side of the substrate is Pt, Au, ITO, etc.

[0036] Specifically, the organic gallium source is trimethylgallium or triethylgallium.

[0037] Specifically, the material of the electrode layer is gold, and other materials such as Ti, Pt, Al, Ni or ITO may also be selected.

[0038] Specifically, the shape of the electrode layer is interdigitated electrodes, comb-shaped electrodes, parallel square electrodes or nested ring electrodes.

[0039] Specifically, the first contact electrode and the second contact electrode are both gold wire leads.

[0040] Example 1 A method for preparing a mixed-phase gallium oxide thin film comprises the following steps: S11: sputtering a Pt metal film on one surface of the substrate; after sputtering, placing the substrate in an MOCVD reaction chamber, with one side of the metal film close to the substrate tray; S12: Use a baking belt to heat the organic source pipeline; rotate the substrate tray along the central axis at a speed of 20-100 rpm to heat the substrate tray to 720°C (the reaction temperature of β-phase gallium oxide); set the main carrier gas flow rate to 500 sccm, select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 200 sccm, which is passed into the reaction chamber. The chamber pressure is 3000 Pa and maintained for 20 min to grow β-phase gallium oxide; during this period, the pusher of the gallium organic source pipeline is 100 sccm, and the organic source bottle is in a closed state; S13: The substrate tray temperature is lowered to 680°C (α-phase gallium oxide reaction temperature), and a gallium organic source and an oxygen source are introduced into the reaction chamber at the same time. The gallium source cold trap temperature is set to 10°C, the gallium source carrier gas flow rate is set to 5.3 sccm, the gallium organic source pipeline pusher is set to 100 sccm, the oxygen source flow rate is set to 400 sccm, the main carrier gas flow rate is set to 1500 sccm, and the chamber pressure is set to 1000 Pa; S14: epitaxial growth for 90 min to form a gallium oxide film with a thickness of 120 nm; S15: After the growth is completed, the temperature is lowered to room temperature and the film is taken out to complete the preparation of the mixed-phase gallium oxide film on the c-plane sapphire substrate. The obtained mixed-phase gallium oxide film was characterized by SEM, and its surface morphology was obtained as follows: Figure 1 As shown, it can be seen from the figure that grains are formed on the surface of the mixed-phase gallium oxide film.

[0041] The obtained mixed-phase gallium oxide film was characterized by XRD, such as Figure 2 As shown in the figure, in addition to the diffraction peak of 41.68° of c-Al2O3 as the substrate, a diffraction peak with a peak value of 40.24° can be clearly obtained, corresponding to the (0006) crystal orientation of α-Ga2O3, and the other three diffraction peaks with peak values ​​of 18.9°, 38.4° and 59.2°, respectively, corresponding to the (-201), (-402) and (-603) crystal orientations of β-Ga2O3. Figure 3 As shown, the band gap width of the mixed-phase gallium oxide film is 5.39 eV, indicating that the mixed-phase gallium oxide film prepared by the preparation method of the present invention has a larger band gap width.

[0042] Example 2 A method for preparing a mixed-phase gallium oxide thin film comprises the following steps: S11: sputtering an Au metal film on one surface of the substrate; after sputtering, placing the substrate in an MOCVD reaction chamber, with one side of the metal film close to the substrate tray; S12: Use a baking belt to heat the organic source pipeline; rotate the substrate tray along the central axis at a speed of 20-100 rpm to heat the substrate tray to 730°C (the reaction temperature of β-phase gallium oxide); set the main carrier gas flow rate to 1000 sccm, select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 200 sccm, which is passed into the reaction chamber. The chamber pressure is 3000 Pa and maintained for 15 minutes to grow β-phase gallium oxide; during this period, the pusher of the gallium organic source pipeline is 100 sccm, and the organic source bottle is in a closed state; S13: The substrate tray temperature is lowered to 690°C (α-phase gallium oxide reaction temperature), and a gallium organic source and an oxygen source are introduced into the reaction chamber at the same time. The gallium source cold trap temperature is set to 10°C, the gallium source carrier gas flow rate is set to 6 sccm, the gallium organic source pipeline pusher is set to 100 sccm, the oxygen source flow rate is set to 500 sccm, the main carrier gas flow rate is set to 1500 sccm, and the chamber pressure is set to 1200 Pa; S14: epitaxial growth for 90 min to form a gallium oxide film with a thickness of 140 nm; S15: After the growth is completed, the temperature is lowered to room temperature and the film is taken out to complete the preparation of the mixed-phase gallium oxide film on the c-plane sapphire substrate. The obtained mixed-phase gallium oxide film was characterized by SEM, and it can be seen that grains are formed on the surface of the mixed-phase gallium oxide film. The mixed-phase gallium oxide film was characterized by XRD, and the band gap width was 5.39 eV, indicating that the mixed-phase gallium oxide film prepared by the preparation method of the present invention has a large band gap width.

[0043] Example 3 A method for preparing a mixed-phase gallium oxide thin film comprises the following steps: S11: sputtering a Pt metal film on one surface of the substrate; after sputtering, placing the substrate in an MOCVD reaction chamber, with one side of the metal film close to the substrate tray; S12: Use a baking belt to heat the organic source pipeline; rotate the substrate tray along the central axis at a speed of 20-100 rpm to heat the substrate tray to 760°C (the reaction temperature of β-phase gallium oxide); set the main carrier gas flow rate to 1000 sccm, select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 100 sccm, which is passed into the reaction chamber. The chamber pressure is 2000 Pa and maintained for 10 min to grow β-phase gallium oxide; during this period, the pusher of the gallium organic source pipeline is 100 sccm, and the organic source bottle is in a closed state; S13: The substrate tray temperature is lowered to 650°C (α-phase gallium oxide reaction temperature), and a gallium organic source and an oxygen source are introduced into the reaction chamber at the same time. The gallium source cold trap temperature is set to 10°C, the gallium source carrier gas flow rate is set to 5.3 sccm, the gallium organic source pipeline pusher is set to 100 sccm, the oxygen source flow rate is set to 400 sccm, the main carrier gas flow rate is set to 1500 sccm, and the chamber pressure is set to 1000 Pa; S14: epitaxial growth for 90 min to form a gallium oxide film with a thickness of 120 nm; S15: After the growth is completed, the temperature is lowered to room temperature and taken out, thereby completing the preparation of the mixed-phase gallium oxide film on the c-plane sapphire substrate.

[0044] In order to further improve the crystal quality of the mixed-phase gallium oxide film during the preparation process, step S15 also includes: performing thermal annealing treatment at a certain temperature and atmosphere for an appropriate time; the annealing conditions are: annealing treatment at 600° C. in an oxygen atmosphere for 20 min.

[0045] The obtained mixed-phase gallium oxide film was characterized by SEM, and it can be seen that grains are formed on the surface of the mixed-phase gallium oxide film. The mixed-phase gallium oxide film was characterized by XRD, and the band gap width was 5.39 eV, indicating that the mixed-phase gallium oxide film prepared by the preparation method of the present invention has a large band gap width.

[0046] Example 4 The present embodiment provides a mixed-phase gallium oxide ultraviolet detector, which comprises, from bottom to top, a substrate, a mixed-phase gallium oxide thin film disposed on the substrate, an electrode layer disposed on the surface of the mixed-phase gallium oxide thin film on the side away from the double-polished substrate; gold wire leads are bonded to the positive electrode and the negative electrode in the electrode layer; The thickness of the mixed-phase gallium oxide film is 100 nm; the electrode layer is a gold interdigital electrode with a thickness of 60 nm; the interdigital electrode has an interdigital width of 10 μm, a spacing of 10 μm, and a number of interdigital pairs of 25 pairs.

[0047] The preparation method comprises the following steps: S1: growing mixed-phase gallium oxide thin films on c-plane sapphire substrates; S2: forming an electrode mask on the mixed-phase gallium oxide film by using a photolithography process, sputtering metal by using a coating machine, with a sputtering current of 6 mA and a sputtering time of 15 min; removing the photoresist by ultrasonication to prepare an electrode layer; S3: Bonding gold wire leads to the positive electrode and the negative electrode of the electrode layer respectively.

[0048] The schematic diagram of the structure of the ultraviolet detector prepared in this embodiment is as follows: Figure 4 The UV detector was tested, and the test results are shown as follows. Figure 5 The figure shows the time response characteristic curve of the ultraviolet detector. It can be seen that the device can respond to 222nm light and has good stability.

[0049] Example 5 The present embodiment provides a mixed-phase gallium oxide ultraviolet detector, which comprises, from bottom to top, a substrate, a mixed-phase gallium oxide thin film disposed on the substrate, an electrode layer disposed on the surface of the mixed-phase gallium oxide thin film on the side away from the double-polished substrate; gold wire leads are bonded to the positive electrode and the negative electrode in the electrode layer; The thickness of the mixed-phase gallium oxide film is 130 nm; the electrode layer is a Pt interdigitated electrode with a thickness of 100 nm; the interdigitated electrode has an interdigital width of 10 μm, a spacing of 10 μm, and a number of 25 pairs of interdigits.

[0050] The preparation method comprises the following steps: S1: growing mixed-phase gallium oxide thin films on c-plane sapphire substrates; S2: forming an electrode mask on the mixed-phase gallium oxide film by using a photolithography process, sputtering metal by using a coating machine, with a sputtering power of 100 W and a sputtering time of 20 min; removing the photoresist by ultrasonication to prepare an electrode layer; S3: Bonding gold wire leads to the positive electrode and the negative electrode of the electrode layer respectively.

[0051] The schematic diagram of the structure of the ultraviolet detector prepared in this embodiment is as follows: Figure 4 The ultraviolet detector was tested, and the test results showed that the mixed-phase gallium oxide ultraviolet detector has good solar-blind ultraviolet detection performance and a faster light response speed.

[0052] The advantages of the present invention are: in view of the problem that various current growth methods are difficult to accurately control the growth process of gallium oxide, this scheme uses MOCVD technology, and realizes the mixing of a small amount of β-phase gallium oxide in the α-phase gallium oxide film by processing the substrate, adding the β-phase gallium oxide pre-reaction process and controlling the growth conditions. Moreover, this scheme can more accurately control the growth process of the β-phase, so that the β-phase gallium oxide nucleates on the substrate surface, and the mixing of the β-phase will not cause significant changes in the crystal quality and absorption spectrum of the film, so that a high-quality wide-bandgap gallium oxide film can be obtained, thereby realizing effective detection of shorter wavelength light, and giving full play to the advantage of the α-phase gallium oxide having a larger bandgap width. In addition, the grain boundaries of the mixed-phase gallium oxide film can accelerate carrier recombination, so that the fall time of the ultraviolet detector is reduced.

[0053] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0054] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A mixed-phase gallium oxide thin film, characterized in that: Prepared by the following method: S11: sputtering a metal film on one surface of the substrate; after sputtering, placing the substrate in an MOCVD reaction chamber, with one side of the metal film close to the substrate tray; S12: heating the substrate tray to 710-760° C. and maintaining the temperature for 10-20 min; during the heating period, an oxygen source is introduced into the MOCVD reaction chamber; S13: lowering the temperature of the substrate tray to 650-690° C., while introducing a gallium organic source and an oxygen source; S14: maintaining a period of time according to demand, epitaxially growing a gallium oxide film of a certain thickness; S15: After the growth is completed, the temperature is lowered to room temperature and taken out, thereby completing the preparation of the mixed-phase gallium oxide film on the c-plane sapphire substrate.

2. A mixed-phase gallium oxide thin film according to claim 1, characterized in that: The mixed-phase gallium oxide film has a thickness of 80-250 nm and a bandgap width greater than 5.2 eV.

3. A mixed-phase gallium oxide thin film according to claim 2, characterized in that: In step S12, the oxygen source flow rate is 100-200 sccm, the main carrier gas flow rate is 500-1000 sccm, and the chamber pressure is maintained at 2000-3000 Pa.

4. The mixed-phase gallium oxide thin film according to claim 3, characterized in that: The oxygen source is high-purity oxygen; the substrate is a double-polished c-plane sapphire substrate.

5. The mixed-phase gallium oxide thin film according to claim 1, characterized in that: When heating the substrate tray in step S12, the substrate tray is rotated along the central axis at a speed of 20-100 rpm.

6. A mixed-phase gallium oxide thin film according to any one of claims 1 to 5, characterized in that: In step S13, the gallium organic source cold trap temperature is 5-10° C., the gallium organic source carrier gas flow rate is 5-10 sccm, the oxygen source flow rate is 200-500 sccm, the main carrier gas flow rate is 1500-3000 sccm, and the chamber pressure is maintained at 1000-2000 Pa.

7. A mixed-phase gallium oxide ultraviolet detector, characterized in that: The invention comprises, from bottom to top, a substrate, a mixed-phase gallium oxide thin film as claimed in claim 1 arranged on the substrate, and an electrode layer arranged on the surface of the mixed-phase gallium oxide thin film on the side away from the double-polished substrate; a first contact electrode is arranged on the positive electrode in the electrode layer, and a second contact electrode is arranged on the negative electrode in the electrode layer.

8. The ultraviolet detector according to claim 7, characterized in that: The first contact electrode and the second contact electrode are both gold wire leads.

9. The mixed-phase gallium oxide ultraviolet detector according to claim 8, characterized in that: The electrode layer is an interdigitated electrode with a thickness of 40-80 nm; the interdigitated electrode has an interdigitated width of 10 μm, an interval of 10 μm, and 25 pairs of interdigitated pairs.

10. The ultraviolet detector according to any one of claims 7 to 9, characterized in that: Prepared by the following method: S1: growing mixed-phase gallium oxide thin films on c-plane sapphire substrates; S2: forming an electrode mask on the mixed-phase gallium oxide film by using a photolithography process, sputtering metal by using a coating machine, and removing the photoresist by ultrasonic wave to prepare an electrode layer; S3: Bonding gold wires to the positive electrode and the negative electrode of the electrode layer as contact electrodes.

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