Alpha-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 an alpha-phase gallium oxide thin film, an ultraviolet detector and a preparation method. The preparation method comprises the following steps: selecting a c-plane sapphire substrate, and placing the substrate in an MOCVD reaction chamber; the reaction chamber is alternately inflated and vacuumized, and the substrate tray is heated to 650-730 DEG C; introducing an oxygen source into the MOCVD reaction chamber, and supplying a reaction source to form alpha-Ga2O3 on the surface of the substrate; adjusting the flow of the carrier gas to 1000-2000 sccm, and continuously supplying an oxygen source and a reaction source to the MOCVD reaction chamber to realize epitaxial growth of the single crystal alpha-Ga2O3 film; and cooling to room temperature and taking out to finish the preparation of the alpha-phase gallium oxide film on the c-plane sapphire substrate. The method has the advantages that the alpha-phase gallium oxide film has high crystallinity and low surface roughness; the ultraviolet detector has the advantages of high responsivity and high response speed, and shows excellent ultraviolet detection performance.

Description

Technical Field

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

[0002] Solar radiation with wavelengths shorter than 280 nm will be absorbed in the stratosphere, resulting in the inability of the earth's surface to detect ultraviolet light in this band (UV-C, also known as solar-blind ultraviolet). Solar-blind ultraviolet photodetectors can selectively detect light with wavelengths in the UV-C region. Since there is no natural background signal on the earth's surface, detection and communication at UV-C wavelengths are sensitive and error-free, making solar-blind ultraviolet photodetectors important in outdoor environments. Currently, solar-blind ultraviolet photodetectors have been widely used in military and civilian fields.

[0003] Gallium oxide (Ga2O3) has a wide band gap (4.7-5.3 eV) and a large absorption coefficient (>10 5 cm −1 ), high breakdown field strength (6–8mV / cm), making it an excellent candidate material for solar-blind UV photodetectors. Among its five crystal forms (α, β, γ, δ, and ε), α-Ga2O3 has the largest band gap, and due to its corundum unit cell structure, it is conducive to heteroepitaxial growth with other corundum or hexagonal materials. These properties make α-Ga2O3 suitable as a high-performance solar-blind UV-C photodetector material.

[0004] The growth of α-Ga2O3 remains a challenging task due to the need to suppress the most thermodynamically stable β-Ga2O3 phase. 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 fabricate α-Ga2O3 thin films. Among them, the MOCVD method can precisely control the film composition, thickness and doping, and can complete the film growth over a large area, uniformly and with high repeatability, which is suitable for large-scale industrial production. At present, the MOCVD method is one of the practical methods for growing β-Ga2O3, but the window for growing single crystal α-Ga2O3 thin films is extremely narrow, making it difficult to achieve heteroepitaxial growth.

[0005] At present, there are methods such as the Mist-CVD method to grow α-Ga2O3 and grow a strain buffer layer followed by a gallium oxide epitaxial layer. The details are as follows: Method 1, Mist-CVD method for growing α-Ga2O3 single crystal thin film: S1: Take an organic gallium source and disperse it in a diluted acid solution to fully dissolve it to obtain a reaction precursor solution, and place the precursor solution in an atomization tank of an atomization-assisted chemical vapor deposition device for standby use; S2: Clean the substrate, dry it thoroughly, and place it in a substrate template in the reaction chamber of the atomization-assisted chemical vapor deposition device; S3: Raise the temperature of the reaction chamber to 420-550°C, and adjust the exhaust gas pumping speed to keep the system pressure difference at 10 Pa-40 Pa; S4: Introduce a mixed gas of N2 and O2 as a carrier gas, set the carrier gas rate, and after the atmosphere in the chamber is stable, introduce the atomized reaction precursor solution to deposit and grow an α-phase gallium oxide single crystal thin film on the substrate.

[0006] This method can achieve reliable growth of α-phase gallium oxide single crystal thin films on aluminum oxide substrates in the temperature range of 450°C-550°C. The half-peak width of the XRD diffraction (0006) crystal plane reaches 0.144°, and the film achieves nearly 100% absorption of visible light below 229 nm.

[0007] Method 2, indium oxide quantum dot buffer layer: (1) epitaxially grow a gallium oxide buffer layer on a substrate; (2) in a very short time, grow a layer of indium oxide quantum dots on the gallium oxide buffer layer to obtain a patterned gallium oxide epitaxial substrate; (3) continue to epitaxially grow an α-phase gallium oxide thin film on the patterned gallium oxide epitaxial substrate until the upper part of the indium oxide quantum dots is covered with gallium oxide.

[0008] This method uses lateral epitaxial growth technology to cover the upper part of indium oxide quantum dots with gallium oxide, so that the dislocations in the window area are cut off and disappear in the lateral growth area. Some dislocations bend 90° toward the lateral growth area and cannot reach the surface of the film, thereby greatly reducing the dislocations. This in-situ maskless lateral epitaxial growth technology greatly optimizes the process steps of traditional lateral epitaxy and reduces etching damage.

[0009] Method 3, pulse epitaxial growth of strain buffer layer: a sapphire substrate is placed in a reaction chamber, and then an oxygen source, a gallium source and / or an aluminum source are separately input into the reaction chamber at different times in a pulse manner. In each growth cycle, any one of the oxygen source, gallium source and / or aluminum source is continuously input into the reaction chamber in a first time period, and then a second time period is interrupted. Then, another one of the oxygen source, gallium source and / or aluminum source is continuously input into the reaction chamber in a third time period, and then a fourth time period is interrupted. To form the above-mentioned one or more α-(Al x Ga 1-x )2O3 strain buffer layer. In the α-(Al x Ga 1-x A gallium oxide epitaxial layer is formed on the )2O3 strain buffer layer.

[0010] This method can avoid the technical difficulty of temperature contradiction in α-Ga2O3 and α-Al2O3 epitaxy, and can also effectively reduce the defect density of α-Ga2O3 epitaxial film, thereby improving the crystal quality of α-Ga2O3 epitaxial film material.

[0011] In the published literature, according to current research, adding boron can stabilize the MOCVD growth of the α phase, using trimethyl gallium (TMG) as a gallium precursor, N2O as an oxygen source and N2 as a carrier gas, with partial pressures of TMG and N2O of 0.053 mbar and 69 mbar, respectively, a deposition temperature of 760°C, and a total gas flow rate and total pressure of 3600 sccm and 500 mbar, respectively. In order to reduce the lattice constant of gallium oxide, boron was added, and the partial pressure of triethyl borate (TEB) was maintained at 0.059 mbar, and a single-oriented α-Ga2O3 film was successfully grown on c-plane sapphire.

[0012] The Mist-CVD method can achieve the growth of single-crystalline α-Ga2O3 thin films, but compared with the conventional chemical vapor deposition (CVD) method, the preparation of gallium oxide films by the Mist-CVD method is affected by many factors such as droplet size, droplet density, and the movement of droplets on the substrate. Since the above factors cannot be accurately controlled at present, there are disadvantages such as low epitaxial growth rate, poor epitaxial film crystallization quality, and high epitaxial film surface roughness.

[0013] Although inserting a buffer layer can release stress and improve the quality of the α-Ga2O3 film to a certain extent, the growth control problem of the buffer layer also needs to be solved. In addition, the insertion of different materials will also lead to problems such as mutual diffusion, affecting the properties of the α-Ga2O3 film.

[0014] Although the method in the literature can grow single-crystalline α-Ga2O3 films by MOCVD, the introduction of impurities will inevitably change the properties of the gallium oxide film, such as reducing the crystal quality and shifting the device response peak. Summary of the invention

[0015] In order to solve the above problems, the present invention provides an α-phase gallium oxide film, an ultraviolet detector and a preparation method.

[0016] The first object of the present invention is to provide an α-phase gallium oxide thin film prepared by the following method: S11: Select a c-plane sapphire substrate and place the substrate in a MOCVD reaction chamber; S12: alternately filling and evacuating the MOCVD reaction chamber, heating the substrate tray to 650-730° C.; setting the main carrier gas flow rate to be greater than 3000 sccm, introducing an oxygen source into the MOCVD reaction chamber, supplying a reaction source, and forming α-Ga2O3 on the surface of the substrate; S13: adjusting the main carrier gas flow rate to 1000-2000 sccm, continuously supplying oxygen source and reaction source to the MOCVD reaction chamber, and realizing epitaxial growth of single crystal α-Ga2O3 thin film; S14: After the growth is completed, the temperature is lowered to room temperature and taken out, thereby completing the preparation of the α-phase gallium oxide thin film on the c-plane sapphire substrate.

[0017] Preferably, the thickness of the α-phase gallium oxide film is 60-200 nm, and the absorption cutoff edge is 220-250 nm.

[0018] Preferably, the oxygen source flow rate in step S12 is 300-700 sccm; the main carrier gas flow rate is set to be greater than 3000 sccm and lasts for 3-5 min.

[0019] Preferably, the oxygen source is high-purity oxygen; and the substrate is a c-plane sapphire substrate.

[0020] 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.

[0021] Preferably, in step S13, the reaction source is a gallium organic source, the gallium organic source cold trap temperature is set to 5-10° C., the gallium organic source carrier gas flow rate is set to 5-10 sccm; and the pressure of the MOCVD reaction chamber is 500-2500 Pa.

[0022] Preferably, in step S13, the speed of epitaxial growth is about 0.5-2 nm / min, and the epitaxial growth time ranges from 60 to 180 min.

[0023] The second purpose of the present invention is to provide an α-phase gallium oxide ultraviolet detector, which includes, from bottom to top: a substrate, an α-phase gallium oxide thin film arranged on the substrate, and an electrode layer arranged on the side of the surface of the α-phase gallium oxide thin film away from the substrate; a first electrode wire is provided on the positive electrode in the electrode layer, and a second electrode wire is provided on the negative electrode in the electrode layer.

[0024] Preferably, the electrode layer is an interdigitated electrode with a thickness of 50-100 nm; the interdigitated electrode has a finger width of 10 μm, a spacing of 10 μm, and a pair number of 25 fingers; the material of one side of the interdigitated electrode is Pt, and the material of the other side is Al or Ti; the first electrode wire and the second electrode wire are silver wires.

[0025] Preferably, it is prepared by the following method: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: forming an electrode mask on the α-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: preparing a first electrode wire and a second electrode wire on the positive electrode and the negative electrode of the electrode layer respectively.

[0026] Compared with the prior art, the present invention can achieve the following beneficial effects: In view of the problems that the current method of growing single-crystal α-Ga2O3 thin films is difficult to accurately control the growth of the epitaxial layer, and the quality of the grown α-Ga2O3 thin films is low, the present invention uses a larger carrier gas flow rate at the beginning of α-Ga2O3 growth to regulate the reaction of the gallium source on the substrate surface and promote the formation of an α phase that is more matched with the substrate lattice. At the same time, by controlling the temperature, gallium source carrier gas flow rate, oxygen flow rate and intracavity pressure, a single-crystal α-Ga2O3 thin film is grown without introducing impurities, and the film has high crystallinity and low surface roughness. Based on the α-Ga2O3 film, a high-performance self-powered ultraviolet detector is prepared, which has the advantages of high responsiveness and fast response speed, and exhibits excellent ultraviolet detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a metal organic chemical vapor deposition (MOCVD) device for preparing an α-phase gallium oxide thin film provided in an embodiment of the present invention.

[0028] Figure 2 is a scanning electron microscope (SEM) image of an α-phase gallium oxide thin film provided by an embodiment of the present invention.

[0029] Figure 3 This is an X-ray diffraction spectrum of the α-phase gallium oxide thin film provided in an embodiment of the present invention.

[0030] Figure 4 This is the XRD rocking curve of the (0006) reflection of the α-phase gallium oxide thin film provided in an embodiment of the present invention.

[0031] Figure 5 It is a schematic diagram of the structure of the ultraviolet detector provided in an embodiment of the present invention.

[0032] Figure 6 It is the time response characteristic curve of the ultraviolet detector provided by the embodiment of the present invention.

[0033] Reference numerals: 1. Substrate; 2. α-phase gallium oxide thin film; 3. Al single-sided interdigitated electrode layer; 4. Pt single-sided interdigitated electrode layer; 5. Silver paste; 6. Silver thread. DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] The present invention provides an α-phase gallium oxide thin film, which is specifically prepared by the following method: S11: Select a c-plane sapphire substrate and place the substrate in a MOCVD reaction chamber; S12: alternately filling and evacuating the MOCVD reaction chamber, repeating three times, rotating the substrate tray along the central axis at a speed of 20-100 rpm, heating the substrate tray to a reaction temperature of 650-730° C.; setting the main carrier gas flow rate to be greater than 3000 sccm, introducing an oxygen source and a reaction source into the MOCVD reaction chamber, so that α-Ga2O3 is formed on the surface of the substrate; Specifically, high-purity oxygen is selected as the oxygen source, and the oxygen source flow rate is 300-700 sccm; the reaction source is selected as a gallium organic source, the gallium organic source cold trap temperature is set to 5-10°C, and the gallium organic source carrier gas flow rate is set to 5-10 sccm; the main carrier gas flow rate is set to be greater than 3000 sccm and lasts for 3-5 min; S13: adjusting the main carrier gas flow rate to 1000-2000 sccm, continuously supplying oxygen source and reaction source to the MOCVD reaction chamber, and controlling the chamber pressure within the range of 500-2500 Pa to achieve epitaxial growth of single crystal α-Ga2O3 thin film; Specifically, the epitaxial growth rate is about 0.5-2 nm / min, and the epitaxial growth time ranges from 60 to 180 min; S14: After the growth is completed, the temperature is lowered to room temperature and the film is taken out, thereby completing the preparation of the α-phase gallium oxide thin film on the c-plane sapphire substrate.

[0037] The thickness of α-phase gallium oxide film is 60-200 nm, and the absorption cutoff edge is 220-250 nm.

[0038] Specifically, the oxygen source may be one or more of oxygen, N2O, and water vapor.

[0039] In order to further improve the crystal quality of the α-phase gallium oxide thin film during the preparation process, step S14 also includes (performed after taking out the sample): performing a thermal annealing treatment at a certain temperature and atmosphere for an appropriate time. The annealing conditions are: annealing treatment at 400-600°C, in an atmosphere of oxygen, nitrogen, argon, air or a mixed gas for 5-120 min.

[0040] The present invention also provides a self-powered ultraviolet detector, which includes, from bottom to top: a substrate, an α-phase gallium oxide thin film arranged on the substrate, and an electrode layer arranged on the side of the surface of the α-phase gallium oxide thin film facing away from the substrate; a first electrode wire is provided on the positive electrode in the electrode layer, and a second electrode wire is provided on the negative electrode in the electrode layer.

[0041] Preferably, the electrode layer is an interdigitated electrode with a thickness of 50-100 nm; the interdigitated electrode has a finger width of 10 μm, a spacing of 10 μm, and a pair number of 25 fingers; the material of one side of the interdigitated electrode is Pt, and the material of the other side is Al or Ti; the first electrode wire and the second electrode wire are silver wires.

[0042] Preferably, the preparation method comprises the following steps: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: forming an electrode mask on the α-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: preparing a first electrode wire and a second electrode wire on the positive electrode and the negative electrode of the electrode layer respectively.

[0043] Specifically, the substrate is a c-plane sapphire substrate, including a-plane, m-plane, and r-plane sapphire substrates.

[0044] Specifically, the organic gallium source is trimethylgallium or triethylgallium.

[0045] Specifically, the material of the electrode layer is Al / Pt, and other materials such as Ti / Pt, Ti / Au, Al / Au, etc. may also be used.

[0046] Specifically, the shape of the electrode layer is interdigitated electrodes, comb-shaped electrodes, parallel square electrodes or nested ring electrodes.

[0047] Specifically, the first electrode wire and the second electrode wire are both silver wires.

[0048] Specifically, step S2 specifically includes: using negative photoresist to form a finger electrode mask on one side of the finger electrode on the α-phase gallium oxide film; using magnetron sputtering technology to form a Pt electrode, the sputtering gas is Ar, the power is 50-150 W, and the time is 10-30 min; removing the colloidal mask by ultrasound; then using negative photoresist to form a mask on the other side of the finger electrode, using magnetron sputtering technology to form an Al or Ti electrode, the time is 20-40 min; removing the colloidal mask by ultrasound.

[0049] Example 1 This embodiment provides a method for preparing an α-phase gallium oxide thin film, using Figure 1 The MOCVD device shown in the figure is used to prepare α-Ga2O3 thin film. Specifically, the following steps are included: S11: Select a substrate and place it in a MOCVD reaction chamber; S12: The reaction chamber is alternately filled with 1000 sccm for 10 min and evacuated to 20 Pa, and the process is repeated three times. The substrate tray is rotated at a speed of 20 rpm, and the substrate tray is heated to 680°C (this step is to reduce impurities in the reaction chamber). The main carrier gas flow rate is set, and an oxygen source and a reaction source are introduced into the MOCVD reaction chamber to form α-Ga2O3 on the substrate surface. Select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 500 sccm; select triethylgallium (TEG) as the gallium organic source as the reaction source, set the gallium organic source cold trap temperature to 10°C, and set the gallium organic source carrier gas flow rate to 5 sccm; set the main carrier gas flow rate to 3000 sccm for 3 min; S13: Changing the carrier gas flow rate to 1500 sccm, continuously supplying the oxygen source and the reaction source to the reaction chamber, and controlling the chamber pressure at 1500 Pa to achieve epitaxial growth of single crystal α-Ga2O3 thin film; The growth time was 90 min and the film thickness was 120 nm; S14: After the growth is completed, the substrate is taken out after cooling to room temperature at a rate of 0.3°C / s, thereby completing the preparation of the α-phase gallium oxide thin film.

[0050] The α-Ga2O3 film obtained in Example 1 was characterized by SEM, and its surface morphology was obtained as shown in the following figure: Figure 2 As shown in the figure, it can be seen that the surface flatness of the α-Ga2O3 film is relatively high.

[0051] The α-Ga2O3 film obtained in Example 1 was characterized by XRD. Figure 3 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. Figure 4 As shown, the half-peak width of the rocking curve of the α-Ga2O3 (0006) crystal orientation is only 0.05°, indicating that the α-Ga2O3 film prepared by the preparation method of the present invention is a single crystal film with high crystal quality.

[0052] A method for preparing an ultraviolet detector is also provided, which specifically comprises the following steps: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: Use negative photoresist to form 25 interdigital electrode masks with a length of 500 μm, a width of 10 μm and a spacing of 30 μm on one side of the interdigital electrode on the α-phase gallium oxide film; use magnetron sputtering technology to form a Pt electrode, with Ar as the sputtering gas, a power of 100 W and a time of 20 min; remove the colloidal mask by ultrasound; then use negative photoresist to form a mask on the other side of the interdigital electrode, and use magnetron sputtering technology to form an Al electrode for 30 min; remove the colloidal mask by ultrasound; S3: Fix the silver wire on the interdigital electrode using silver paste, and then heat and solidify the silver paste at 150°C to obtain the lead-out electrode, and finally obtain the α-Ga2O3 ultraviolet detector.

[0053] The schematic diagram of the structure of the ultraviolet detector prepared in this embodiment is as follows: Figure 5 As shown. It includes a substrate 1, an α-phase gallium oxide film 2 arranged on the substrate 1, and an electrode layer arranged on the surface of the α-phase gallium oxide film 2 facing away from the substrate; the electrode layer is an interdigitated electrode, including an Al single-sided interdigitated electrode layer 3 and a Pt single-sided interdigitated electrode layer 4; silver paste 5 and silver wire 6 are provided on the positive electrode and the negative electrode in the electrode layer.

[0054] Testing of UV detectors, Figure 6 This is the time response characteristic curve of the ultraviolet detector in the present invention. It can be seen that the device can respond to 222 nm light under 0V bias, with a responsivity of 30 mA / W, has good day-blind ultraviolet detection performance, and has a fast light response speed.

[0055] Example 2 A method for preparing an α-phase gallium oxide thin film comprises the following steps: S11: Select a substrate and place it in a MOCVD reaction chamber; S12: The reaction chamber is alternately filled with 1000 sccm for 10 min and evacuated to 20 Pa, and the process is repeated three times. The substrate tray is rotated at a speed of 20 rpm and heated to 700°C. The main carrier gas flow rate is set, and an oxygen source and a reaction source are introduced into the MOCVD reaction chamber to form α-Ga2O3 on the substrate surface. Select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 700 sccm; select triethylgallium (TEG) as the gallium organic source as the reaction source, set the gallium organic source cold trap temperature to 10°C, and set the gallium organic source carrier gas flow rate to 4 sccm; set the main carrier gas flow rate to 3200 sccm for 5 min; S13: Changing the carrier gas flow rate to 1500 sccm, continuously supplying the oxygen source and the reaction source to the reaction chamber, and controlling the chamber pressure at 1500 Pa to achieve epitaxial growth of single crystal α-Ga2O3 thin film; The growth time was 90 min and the film thickness was 100 nm; S14: After the growth is completed, the substrate is taken out after cooling to room temperature at a rate of 0.3°C / s, thereby completing the preparation of the α-phase gallium oxide thin film.

[0056] A method for preparing an ultraviolet detector is also provided, which specifically comprises the following steps: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: Use negative photoresist to form 25 interdigital electrode masks with a length of 500 μm, a width of 10 μm and a spacing of 30 μm on one side of the interdigital electrode on the α-phase gallium oxide film; use magnetron sputtering technology to form a Pt electrode with Ar as the sputtering gas, a power of 100 W and a time of 20 min; remove the colloidal mask by ultrasound; then use negative photoresist to form a mask on the other side of the interdigital electrode, and use magnetron sputtering technology to form a Ti electrode for 20 min; remove the colloidal mask by ultrasound; S3: Fix the silver wire on the interdigital electrode using silver paste, and then heat and solidify the silver paste at 150°C to obtain the lead-out electrode, and finally obtain the α-Ga2O3 ultraviolet detector.

[0057] Example 3 A method for preparing an α-phase gallium oxide thin film comprises the following steps: S11: Select a substrate and place it in a MOCVD reaction chamber; S12: the reaction chamber is alternately filled with 1000 sccm for 10 min and evacuated to 20 Pa, and the process is repeated three times, the substrate tray is rotated at a speed of 20 rpm, and the substrate tray is heated to 720° C.; the main carrier gas flow rate is set, and an oxygen source and a reaction source are introduced into the MOCVD reaction chamber to form α-Ga2O3 on the substrate surface; Select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 500 sccm; select triethylgallium (TEG) as the gallium organic source as the reaction source, set the gallium organic source cold trap temperature to 10°C, and set the gallium organic source carrier gas flow rate to 5.3 sccm; set the main carrier gas flow rate to 3000 sccm for 5 min; S13: Changing the carrier gas flow rate to 2000 sccm, continuously supplying the oxygen source and the reaction source to the reaction chamber, and controlling the chamber pressure at 1200 Pa to achieve epitaxial growth of single crystal α-Ga2O3 thin film; The growth time was 90 min and the film thickness was 140 nm; S14: After the growth is completed, the substrate is taken out after cooling to room temperature at a rate of 0.3°C / s, thereby completing the preparation of the α-phase gallium oxide thin film.

[0058] A method for preparing an ultraviolet detector is also provided, which specifically comprises the following steps: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: Use negative photoresist to form 25 interdigital electrode masks with a length of 500 μm, a width of 10 μm and a spacing of 30 μm on one side of the interdigital electrode on the α-phase gallium oxide film; use magnetron sputtering technology to form a Pt electrode, with Ar as the sputtering gas, a power of 100 W and a time of 20 min; remove the colloidal mask by ultrasound; then use negative photoresist to form a mask on the other side of the interdigital electrode, and use magnetron sputtering technology to form an Al electrode for 30 min; remove the colloidal mask by ultrasound; S3: Fix the silver wire on the interdigital electrode using silver paste, and then heat and solidify the silver paste at 150°C to obtain the lead-out electrode, and finally obtain the α-Ga2O3 ultraviolet detector.

[0059] Example 4 A method for preparing an α-phase gallium oxide thin film comprises the following steps: S11: Select a substrate and place it in a MOCVD reaction chamber; S12: The reaction chamber is alternately filled with 1000 sccm for 10 min and evacuated to 20 Pa, and the process is repeated three times. The substrate tray is rotated at a speed of 20 rpm and heated to 690°C. The main carrier gas flow rate is set, and an oxygen source and a reaction source are introduced into the MOCVD reaction chamber to form α-Ga2O3 on the substrate surface. Select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 500 sccm; select triethylgallium (TEG) as the gallium organic source as the reaction source, set the gallium organic source cold trap temperature to 5°C, and set the gallium organic source carrier gas flow rate to 5.3 sccm; set the main carrier gas flow rate to 3000 sccm for 3 min; S13: Changing the carrier gas flow rate to 1000 sccm, continuously supplying the oxygen source and the reaction source to the reaction chamber, and controlling the chamber pressure at 1500 Pa to achieve epitaxial growth of single crystal α-Ga2O3 thin film; The growth time was 90 min and the film thickness was 70 nm; S14: After the growth is completed, the substrate is taken out after cooling to room temperature at a rate of 0.3°C / s, thereby completing the preparation of the α-phase gallium oxide thin film.

[0060] A method for preparing an ultraviolet detector is also provided, which specifically comprises the following steps: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: Use negative photoresist to form 25 interdigital electrode masks with a length of 500 μm, a width of 10 μm and a spacing of 30 μm on one side of the interdigital electrode on the α-phase gallium oxide film; use magnetron sputtering technology to form a Pt electrode, with Ar as the sputtering gas, a power of 100 W and a time of 20 min; remove the colloidal mask by ultrasound; then use negative photoresist to form a mask on the other side of the interdigital electrode, and use magnetron sputtering technology to form an Al electrode for 30 min; remove the colloidal mask by ultrasound; S3: Use silver paste to fix the silver wire on the interdigital electrode, and then heat and solidify the silver paste at 150°C to obtain the lead-out electrode, and finally obtain the α-Ga2O3 ultraviolet detector.

[0061] Example 5 A method for preparing an α-phase gallium oxide thin film comprises the following steps: S11: Select a substrate and place it in a MOCVD reaction chamber; S12: the reaction chamber is alternately filled with 1000 sccm for 10 min and evacuated to 20 Pa, and the process is repeated three times, the substrate tray is rotated at a speed of 20 rpm, and the substrate tray is heated to 700° C.; the main carrier gas flow rate is set, and an oxygen source and a reaction source are introduced into the MOCVD reaction chamber to form α-Ga2O3 on the substrate surface; Select high-purity oxygen as the oxygen source, and the oxygen source flow rate is 500 sccm; select triethylgallium (TEG) as the gallium organic source as the reaction source, set the gallium organic source cold trap temperature to 10°C, and set the gallium organic source carrier gas flow rate to 5 sccm; set the main carrier gas flow rate to 3000 sccm for 3 min; S13: Changing the carrier gas flow rate to 1000 sccm, continuously supplying the oxygen source and the reaction source to the reaction chamber, and controlling the chamber pressure at 500 Pa to achieve epitaxial growth of single crystal α-Ga2O3 thin film; The growth time was 120 min and the film thickness was 150 nm; S14: After the growth is completed, the substrate is taken out after cooling to room temperature at a rate of 0.3°C / s, thereby completing the preparation of the α-phase gallium oxide thin film.

[0062] A method for preparing an ultraviolet detector is also provided, which specifically comprises the following steps: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: Use negative photoresist to form 25 interdigital electrode masks with a length of 500 μm, a width of 10 μm and a spacing of 30 μm on one side of the interdigital electrode on the α-phase gallium oxide film; use magnetron sputtering technology to form a Pt electrode, with Ar as the sputtering gas, a power of 100 W and a time of 20 min; remove the colloidal mask by ultrasound; then use negative photoresist to form a mask on the other side of the interdigital electrode, and use magnetron sputtering technology to form an Al electrode for 20 min; remove the colloidal mask by ultrasound; S3: Use silver paste to fix the silver wire on the interdigital electrode, and then heat and solidify the silver paste at 150°C to obtain the lead-out electrode, and finally obtain the α-Ga2O3 ultraviolet detector.

[0063] The α-Ga2O3 films obtained in Example 2 to Example 5 are all single crystal α-Ga2O3 films with high crystallization quality and low surface roughness; the α-Ga2O3 ultraviolet detectors obtained in Implementation Case 2 to Implementation Case 5 have good day-blind ultraviolet detection performance and fast light response speed.

[0064] The advantages of the present invention are: the present invention uses the MOCVD method to control the epitaxy of α-Ga2O3 on the substrate surface at the beginning of growth and accurately controls the growth temperature, gallium source carrier gas flow rate, oxygen flow rate and chamber pressure to achieve the growth of a single crystal α-Ga2O3 film, and the film has high crystallinity and low surface roughness. The ultraviolet detector based on the α-Ga2O3 film of the present invention has the advantages of high responsiveness and fast response speed, and exhibits excellent ultraviolet detection performance.

[0065] 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.

[0066] 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. An α-phase gallium oxide thin film, characterized in that: Prepared by the following method: S11: Select a c-plane sapphire substrate and place the substrate in a MOCVD reaction chamber; S12: alternately filling and evacuating the MOCVD reaction chamber, heating the substrate tray to 650-730° C.; setting the main carrier gas flow rate to be greater than 3000 sccm, introducing an oxygen source into the MOCVD reaction chamber, supplying a reaction source, and forming α-Ga2O3 on the surface of the substrate; S13: adjusting the main carrier gas flow rate to 1000-2000 sccm, continuously supplying oxygen source and reaction source to the MOCVD reaction chamber, and realizing epitaxial growth of single crystal α-Ga2O3 thin film; S14: After the growth is completed, the temperature is lowered to room temperature and taken out, thereby completing the preparation of the α-phase gallium oxide thin film on the c-plane sapphire substrate.

2. The α-phase gallium oxide thin film according to claim 1, characterized in that: The thickness of the α-phase gallium oxide film is 60-200 nm, and the absorption cutoff edge is 220-250 nm.

3. The α-phase gallium oxide thin film according to claim 2, characterized in that: The oxygen source flow rate in step S12 is 300-700 sccm; the main carrier gas flow rate is set to be greater than 3000 sccm and lasts for 3-5 min.

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

5. The α-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. An α-phase gallium oxide thin film according to any one of claims 1 to 5, characterized in that: In step S13, the reaction source is a gallium organic source, the gallium organic source cold trap temperature is set to 5-10° C., the gallium organic source carrier gas flow rate is set to 5-10 sccm; and the pressure of the MOCVD reaction chamber is 500-2500 Pa.

7. The α-phase gallium oxide thin film according to claim 6, characterized in that: The epitaxial growth rate in step S13 is about 0.5-2 nm / min, and the epitaxial growth time ranges from 60 to 180 min.

8. An α-phase gallium oxide ultraviolet detector, characterized in that: The invention comprises, from bottom to top, a substrate, an α-phase gallium oxide thin film as claimed in claim 1 arranged on the substrate, and an electrode layer arranged on the surface of the α-phase gallium oxide thin film facing away from the substrate; a first electrode wire is arranged on the positive electrode in the electrode layer, and a second electrode wire is arranged on the negative electrode in the electrode layer.

9. The α-phase gallium oxide ultraviolet detector according to claim 8, characterized in that: The electrode layer is an interdigitated electrode with a thickness of 50-100 nm; the interdigitated electrode has an interdigitated width of 10 μm, an interval of 10 μm, and 25 pairs of interdigitated electrodes; the material of one side of the interdigitated electrode is Pt, and the material of the other side is Al or Ti; the first electrode wire and the second electrode wire are silver wires.

10. An α-phase gallium oxide ultraviolet detector according to claim 8 or 9, characterized in that: Prepared by the following method: S1: Growth of α-phase gallium oxide thin film on c-plane sapphire substrate; S2: forming an electrode mask on the α-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: preparing a first electrode wire and a second electrode wire on the positive electrode and the negative electrode of the electrode layer respectively.

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