Fluorine ion implanted p-type gallium oxide thin film, ultraviolet photodiode and preparation method of p-type gallium oxide thin film and ultraviolet photodiode

Abstract

The invention discloses a p-type gallium oxide thin film adopting fluorine ion implantation, an ultraviolet photodiode and a preparation method, and belongs to the technical field of semiconductor preparation. According to the method, monovalent fluorine positive ions are injected into a high-electric-property heavily-doped p-type gallium oxide thin film, after fluorine ions (F < + >) replace oxygen (O), O replacement is achieved, the O becomes interstitial impurities as little as possible, electrons bound by existing Ga-O bonds at other positions can be further attracted due to positive electricity, holes are formed in the existing Ga-O bonds at other positions, and therefore the high-electric-property heavily-doped p-type gallium oxide thin film is formed. Fluorine ions (F < + >) play a role of acceptor impurities. The method not only solves the problem that a suitable p-type doping method is lacked at the present stage, but also effectively overcomes the difficulty that the acceptor doping concentration for generating p-type gallium oxide is difficult to adjust in the prior art, and successfully prepares the p-type single crystal gallium oxide film with high hole carrier concentration, low acceptor ionization energy and low defect rate in a specific region.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor preparation, and relates to a p-type gallium oxide film and an ultraviolet photodiode implanted with fluorine ions and a preparation method thereof. Background Art

[0002] Ultra-wide bandgap monoclinic gallium oxide β-Ga 2 O 3 The bandgap width is 4.8-4.9 eV, the breakdown electric field strength is 8MV / cm, the Baliga figure of merit is 3334, and it has excellent thermal stability under normal pressure and temperature conditions. These advantages make β-Ga 2 O 3 It has obvious application advantages in solar-blind ultraviolet photodetectors, ultraviolet photodiodes, photocatalysts, gas sensors, solar cells, phosphors and next-generation ultra-high power power electronic devices.

[0003] Preparation of β-Ga with high carrier concentration and good mobility 2 O 3 Thin films are key technologies for realizing high-voltage, high-power devices and optoelectronic devices. 2 O 3 Thin films have achieved certain research results. Currently, n-type β-Ga with good electrical properties has been achieved. 2 O 3 Doping is to simultaneously add donor impurities such as Si, Ge, Sn, Nb, Zr, Mg, and Fe during the epitaxial growth of gallium oxide thin films to achieve n-type electrical properties. By adjusting the doping concentration of donor impurities, the electron carrier concentration can be adjusted to 10 16 ~10 20 cm -3 within the range of orders of magnitude.

[0004] But currently, how to 2 O 3 To achieve effective p-type electrical properties in the material, both in terms of finding appropriate acceptor doping and exploring effective doping methods are in the initial research stage and face difficulties, which are urgent problems to be solved. The valence band structure of gallium oxide makes its acceptor energy level position deep, making it extremely difficult to lose electrons and difficult to form a p-type hole-conducting semiconductor. In addition, the self-compensation effect introduced by defects will cause the holes that have been formed to be compensated. Therefore, the existence of these defects also directly affects the p-type electrical properties of the prepared gallium oxide material. Based on the research results that have been published so far, it can be found in β-Ga 2 O 3The acceptors that achieve p-type electrical properties are: (1) Mg, Fe, Li, Be, Sr, but the acceptor ionization energies of these acceptor impurities are all greater than 1 eV, making them difficult to ionize, and the p-type electrical properties obtained are very weak. (2) Doping with Zn or Ni, whose acceptor ionization energies are 0.22 - 0.5 eV, still belongs to a relatively deep acceptor energy level. The acceptor ions in (1) and (2) above are all doped in β-Ga 2 O 3 Doping is performed during the epitaxy process, such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and plasma enhanced atomic layer deposition (PEALD). (3) Current research also reports the use of O 2 or N 2 O gas is used as an oxidizing gas, and high-temperature thermal oxidation technology is used to thermally oxidize single-crystal GaN to generate nitrogen (N)-doped β-Ga 2 O 3 N is used as an acceptor impurity. After N doping, a shallow acceptor impurity energy level is introduced at the top of the valence band. 2 or N 2 O high temperature thermal oxidation of GaN to obtain nitrogen-doped p-type β-Ga 2 O 3 The Hall hole carrier concentration of the film is not higher than 2 × 10 17 cm -3 , the corresponding acceptor ionization energy is greater than or equal to 0.087 eV.

[0005] Whether it is p-type doping during epitaxial growth of gallium oxide films (using metal organic chemical vapor deposition, molecular beam epitaxy, plasma enhanced atomic layer deposition and other technologies) or p-type doping during thermal oxidation of gallium oxide films, the p-type gallium oxide films currently generated not only have p-type electrical properties that do not reach the level of heavy doping (hole carrier concentrations are not higher than 2 × 10 17 cm -3 ), and the generated p-type gallium oxide film is a whole layer, and p-type doping cannot be formed in a specific area. Ion implantation technology is a technology that must be used in doping in a specific area, specific depth, and specific concentration, such as forming a heavily doped "source region" or "drain region" in a traditional silicon-based CMOS device, or "body region intentionally doped to complete threshold voltage adjustment". However, for gallium oxide, there has been no public research on obtaining highly electrically doped p-type gallium oxide films by ion implantation. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a p-type gallium oxide film and an ultraviolet photodiode using fluorine ion implantation and a preparation method, so as to solve the problem that the p-type electrical properties of the p-type gallium oxide film generated in the prior art do not reach the order of magnitude of heavy doping and p-type doping cannot be formed in a specific area.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a p-type gallium oxide thin film by fluorine ion implantation comprises the following steps: Step 1: Pretreatment of undoped single crystal β-Ga 2 O 3 film; Step 2: Add the pre-treated non-doped single crystal β-Ga 2 O 3 The set area of ​​the film was injected with monovalent fluoride ions. During the injection process, the ion source was monovalent fluoride ions, the injection angle was 24°, and the injection dose was 6 × 10 16 ~9 ×10 19 ions / cm 2 .

[0008] A further improvement of the present invention is: Preferably, in step 1, the non-doped single crystal β-Ga 2 O 3 The film is obtained by MOCVD outer edge growth.

[0009] Preferably, in step 1, the non-doped β-Ga 2 O 3 The film is n-type, with a thickness of 700 nm and a Hall electron carrier concentration of 1.9 × 10 17 cm -3 .

[0010] Preferably, in step 1, the pretreatment process is to clean the film with an organic solvent and deionized water, and then dry the cleaned film to obtain the pretreated non-doped single crystal β-Ga 2 O 3 film.

[0011] Preferably, in step 2, during the injection process, the injection energy is 45 kV, the injection current is 30 μA, and the injection time is 30 min.

[0012] Preferably, in step 2, the non-doped area is shielded by a mask plate, the mask plate exposes the set area, and doping ions are injected into the set area.

[0013] A p-type gallium oxide film prepared by any one of the above preparation methods using fluorine ion implantation, wherein the p-type gallium oxide film is divided into a doped region and a non-doped region, wherein the doped region is a p-type β-Ga doped with positive monovalent fluorine ions. 2 O 3 , the undoped region is undoped n-type β-Ga 2 O 3 .

[0014] A method for preparing an ultraviolet photodiode comprises obtaining the above-mentioned p-type gallium oxide film, preparing a gold-aluminum electrode on the doped area, and preparing a magnesium-aluminum electrode on the non-doped area.

[0015] An ultraviolet photodiode prepared by the above-mentioned preparation method is characterized in that it includes the above-mentioned p-type gallium oxide film, the doped area of ​​the p-type gallium oxide film is a circular area in the middle of the p-type gallium oxide film, and the area outside the circular area is a non-doped area; a gold-aluminum electrode is arranged at the center position of the doped area; and two magnesium-aluminum electrodes are arranged in the non-doped area, and the two magnesium-aluminum electrodes are symmetrical with respect to the gold-aluminum electrode.

[0016] Preferably, the gold-aluminum electrode is a double-layer electrode, in which gold is in the lower layer and aluminum is in the upper layer; and the magnesium-aluminum electrode is a magnesium-aluminum alloy.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a highly electrically heavily doped p-type gallium oxide film using fluorine ion implantation. The film can overcome the problem of implanting monovalent fluorine positive ions into the highly electrically heavily doped p-type gallium oxide film through ion implantation technology, and not only solves the problem of lack of suitable p-type doping methods at this stage, but also effectively overcomes the problem that highly electrically heavily doped p-type gallium oxide cannot be realized in a local specific area in the prior art, and the acceptor doping concentration of the generated p-type gallium oxide is difficult to adjust, and successfully prepares a p-type single crystal gallium oxide film with high hole carrier concentration, low acceptor ionization energy and low defect rate in a specific area.

[0018] The second aspect of the present invention discloses an ultraviolet Gallium laser based on the heavily doped p-type gallium oxide film, combined with the undoped n-type gallium oxide substrate underneath, using a high work function and low resistivity "lower gold / upper aluminum" structure as an ohmic electrode in the p-type heavily doped gallium oxide region, and using a low work function "magnesium-aluminum" alloy as an ohmic electrode in the undoped n-type gallium oxide region to construct a vertical structure ultraviolet photodiode. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flowchart of the invention; Figure 2 The (100) crystal plane is undoped with β-Ga 2 O 3Schematic diagram of the Tilt angle of the sample for ion implantation; Figure 3 The top view and cross-sectional view of the gallium oxide photodiode; Figure 4 It is p-type heavily doped β-Ga 2 O 3 Thin film vacuum variable temperature Hall test: Hall hole carrier concentration changes with test temperature; Figure 5 It is p-type heavily doped β-Ga 2 O 3 Thin film vacuum variable temperature Hall test: acceptor ionization energy; Figure 6 Based on the ultraviolet photoelectron spectroscopy (UPS) calculation, the p-type heavily doped β-Ga 2 O 3 Work function diagram of ; Figure 7 Based on the ultraviolet photoelectron spectroscopy (UPS) calculation, the non-doped n-type β-Ga 2 O 3 Work function diagram of ; Figure 8 Under zero bias, p-type heavily doped β-Ga 2 O 3 (Hall hole carrier concentration 5 × 10 20 cm -3 ) forms an ohmic contact with gold (work function 5.10 eV); n-type β-Ga 2 O 3 (Hall electron carrier concentration 1.9 × 10 17 cm -3 ) forms an ohmic contact with "magnesium aluminum alloy" (work function 3.66 eV); and the energy band diagram of a pn junction photodiode under zero bias; Fig. 9 It characteristic curves of the gallium oxide photodiode under 254 nm ultraviolet light at zero bias: (a) multiple cycles, (b) single cycle. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings: In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] See also Figure 1 The first aspect of the present invention discloses a method for preparing a highly electrically conductive heavily doped p-type gallium oxide film by fluorine ion implantation, the method comprising the following steps: (1) The gallium oxide film before ion implantation is a non-doped single-crystalline β-Ga grown homoepitaxially based on MOCVD technology. 2 O 3 The film thickness is 700 nm. Due to oxygen vacancies, the non-doped β-Ga 2 O 3 The film has n-type conductivity, and its Hall electron carrier concentration is 1.9 × 10 17 cm -3 .

[0022] (2) The undoped single crystal β-Ga 2 O 3 The film was injected with F + Before use, ultrasonic cleaning is carried out with organic solvents and deionized water. The specific process is: acetone (ultrasonic cleaning for 15 minutes) → ethanol (ultrasonic cleaning for 15 minutes) → deionized water (ultrasonic cleaning for 15 minutes), and then blown dry with a nitrogen gun to remove impurities and oxides on the surface.

[0023] (3) In the set area, ion implantation is performed using an ion implanter (ULVAC IMX-3500). The specific ion implantation parameters are as follows: Table 1 Ion implantation parameters

[0024] The ion source injected in the above-mentioned injection process is an ion source purchased directly from the Songshan Lake Materials Laboratory. In the ion injection process, the corresponding ion implanter is used, and the gas enters the ion source chamber and ionizes F + and other ions, and F is screened out by screening magnetic field + .

[0025] In the above process, the non-doped single crystal β-Ga can be controlled by injecting energy. 2 O 3 The ion implantation depth in the film is specifically fixed at 45 keV in the embodiment of the present invention. Under this implantation energy, the total implantation depth is 420 nm.

[0026] See also Figure 2 In the above process, in order to more accurately achieve the substitution of fluorine ions for oxygen atoms, thereby avoiding the formation of interstitial impurities due to the ion implantation tunneling effect, the ion implanted sample is β-Ga with a (100) crystal plane. 2 O 3 During the ion implantation, the optimized implantation tilt angle was selected: Tilt = 24°. During the ion implantation, the implantation angle was maintained and the gallium oxide sample was rotated at a constant speed to ensure uniform implantation.

[0027] In the above process, the non-doped single crystal β-Ga is controlled by ion implantation dose. 2 O 3 F in thin films + The number of ions implanted is in the range of 6 × 10 16 ions / cm 2 Up to 9 × 10 16 ions / cm 2 When the dose is 6 × 10 16 ions / cm 2 When SRIM simulation is used, we get: F + The peak ion concentration was 2.7 × 10 22 / cm 3 , in the whole injection depth range, F + The average ion doping concentration is 1.06 × 10 22 / cm 3 When the dose is 9 × 10 16 ions / cm 2 When SRIM simulation is used, we get: F + The peak ion concentration was 4.9 × 10 22 / cm 3 ; In the whole injection depth range, F + The average ion doping concentration is 2.36 × 10 22 / cm3 .

[0028] It should be understood that the setting area of ​​the above-mentioned implantation process is set according to the structure of the UV photodiode to be finally prepared. The setting area is the upper surface of the area to be implanted with ions. The non-doped single crystal β-Ga 2 O 3 The undoped regions of the film are implanted with F + ions, the masked areas were not implanted.

[0029] In the above process, the ion implantation energy was controlled so that the ions were not completely implanted to the bottom in the vertical direction, forming a vertical "PN junction" structure of "upper p / lower n". In the horizontal direction, the mask was used to implant F only in the circular range of the mask opening in the center area of ​​the square n-type gallium oxide sample. + Ions are not implanted outside the circular area and remain n-type.

[0030] Rapid thermal annealing (RTA) after ion implantation only activates F + ions without redistribution of ions. Therefore, a "PN junction" structure is formed both vertically and horizontally.

[0031] See also Figure 1 The left process in the figure is the process of preparing a thin film for Hall test. The preparation process includes the following steps: (1) The gallium oxide film before ion implantation is a non-doped single-crystalline β-Ga grown homoepitaxially based on MOCVD technology. 2 O 3 The film thickness is 700 nm. Due to oxygen vacancies, the non-doped β-Ga 2 O 3 The film has n-type conductivity, and its Hall electron carrier concentration is 1.9 × 10 17 cm -3 .

[0032] (2) The undoped single crystal β-Ga 2 O 3 The film was injected with F + Before use, ultrasonic cleaning is carried out with organic solvents and deionized water. The specific process is: acetone (ultrasonic cleaning for 15 minutes) → ethanol (ultrasonic cleaning for 15 minutes) → deionized water (ultrasonic cleaning for 15 minutes), and then blown dry with a nitrogen gun to remove impurities and oxides on the surface.

[0033] (3) For the entire square of undoped single crystal β-Ga 2 O 3 Sample F + Ion implantation.

[0034] (4) After ion implantation, Hall electrodes with “gold below / aluminum above” are sputtered and grown at the four corners of the sample surface; (5) The sample prepared in step (4) is annealed twice, the first annealing is to activate F + ; The second annealing activates the Hall electrode.

[0035] The Hall test was carried out on the samples prepared above, and the test results are as follows: Figure 4 and Figure 5 As shown in Figure F + After ion implantation, the vacuum environment variable temperature Hall test results are shown in the figure. The test temperature (Kelvin temperature) is 150 K to 700 K. The Hall hole carrier concentration increases with the increase of the test temperature. When the Hall test temperature is 150 K, the Hall hole carrier concentration is 3.01149 × 1017 cm -3 ; When the Hall test temperature is 300 K (room temperature), the Hall hole carrier concentration is 8.03003 × 1017 cm -3 ; When the Hall test temperature is 700 K, the Hall hole carrier concentration is 2.18144 × 1019 cm -3 .from Figure 5 It can be seen that the acceptor ionization energy of fluorine calculated based on the variable temperature Hall carrier concentration is 0.086 eV.

[0036] The p-type gallium oxide film obtained by the above preparation method includes an upper layer and a lower layer. The upper layer is injected with F + p-type β-Ga doped with positive monovalent fluoride ions 2 O 3 , the lower layer is undoped n-type β-Ga 2 O 3 .

[0037] The second aspect of the present invention discloses a highly electrically heavily doped p-type gallium oxide film prepared by the above-mentioned preparation method using fluorine ion implantation, the film comprising a doped region and a non-doped region, the doped region being a p-type β-Ga doped with positive monovalent fluorine ions. 2 O 3 , the undoped region is undoped n-type β-Ga 2 O 3 .

[0038] The third aspect of the present invention discloses a method for preparing a diode based on the above-mentioned thin film, comprising the following steps: (1) Obtaining a p-type gallium oxide thin film; in the process of preparing the above-mentioned thin film, the corresponding mask plate is designed and the area is set according to the shape of the ultraviolet photodiode, and finally a p-type gallium oxide thin film that meets the requirements is obtained.

[0039] (2) See Figure 6-Figure 8 , based on the above-mentioned p-type gallium oxide film, the corresponding electrode is prepared. 2 O 3 Sample; and injection F + β-Ga ions are p-type doped 2 O 3 , their work functions are different. Based on the ultraviolet photoelectron spectroscopy (UPS) technology, the present invention measures the non-doped n-type β-Ga 2 O 3 and p-type and doped with β-Ga 2 O 3 Their respective work functions. 2 O 3 Work function, each chooses a metal that is suitable for forming a good ohmic contact. 2 O 3 , select the magnesium-aluminum alloy with low work function (3.66 eV) as the ohmic contact metal electrode; for p-type β-Ga 2 O 3 , select "gold" with high work function (5.10 eV) as the ohmic contact metal electrode, and then deposit metal aluminum on top of the gold to form an electrode structure of "gold below / aluminum above", which further reduces the resistivity of the ohmic electrode.

[0040] (3) Annealing the prepared metal electrode p-type gallium oxide film, the process implemented three times of rapid thermal annealing (RTA): (3-1) The first RTA, in nitrogen atmosphere, the RTA temperature ramp rate is 150℃ / s, the RTA high temperature holding temperature is 370℃, and the RTA high temperature holding time is 60 s. The purpose of this RTA is to form a good ohmic contact between the low work function "magnesium aluminum alloy" and the n-type gallium oxide film.

[0041] (3-2) The second RTA, in nitrogen atmosphere, the RTA temperature ramp rate is 200℃ / s, the RTA high temperature holding temperature is 420℃, and the RTA high temperature holding time is 60 s. The purpose of this RTA is to form a good ohmic contact between the high work function "lower gold / upper aluminum" and the p-type gallium oxide film.

[0042] (3) The third RTA, in nitrogen atmosphere, the RTA temperature change rate is 100℃ / s, the RTA high temperature holding temperature is 700℃, and the RTA high temperature holding time is 70 s. The purpose of this RTA is to activate the F implanted by ions. + ion.

[0043] In the above process, through annealing, the metal is allowed to penetrate into the gallium oxide to a thickness of several nanometers and form an alloy compound, further reducing the contact resistance of the ohmic electrode.

[0044] The ultraviolet photodiode prepared by the method of the present invention comprises the above-mentioned p-type gallium oxide film, the doped region of the p-type gallium oxide film is a circular region in the middle of the p-type gallium oxide film, and the region outside the circular region is a non-doped region; a gold-aluminum electrode is arranged at the center position of the doped region; and two magnesium-aluminum electrodes are arranged in the non-doped region, and the two magnesium-aluminum electrodes are symmetrical with respect to the gold-aluminum electrode.

[0045] Using this "PN junction" structure, in the p-type β-Ga 2 O 3 The circular "gold below / aluminum above" ohmic electrode is grown in the region, and the n-type β-Ga 2 O 3 The regional growth ring "magnesium-aluminum alloy" ohmic electrode. There is a suitable ultraviolet light irradiation area on the gallium oxide PN junction between the two electrodes, which ensures that the ultraviolet photodiode has a large photocurrent. Under zero bias, the ratio of photocurrent to dark current reaches 4.32 × 10 6 .

[0046] See also Fig. 9 , Fig. 9 Figure (a) shows a multi-cycle IV curve of a gallium oxide photodiode measured under deep ultraviolet light irradiation with a wavelength of 254 nm and a power density of 58 μW / cm2 when a zero volt bias is applied. Each cycle includes two states: "UV Light On" and "UV Light Off". The current when the UV Light is On is the photocurrent Ion, and the current when the UV Light is Off is the dark current Ioff. The ratio of photocurrent to dark current (Ion:Ioff) of the gallium oxide photodiode obtained in this embodiment reaches a high 10 6 Order of magnitude.

[0047] Fig. 9 Figure (b) shows a single-cycle IV curve of a gallium oxide photodiode measured under deep ultraviolet light irradiation with a wavelength of 254 nm and a power density of 58 μW / cm2 when a zero volt bias is applied. The rise time (τ r ) and the fall time (decay time τ d ) reflects the response speed, which is generally defined as the time delay between 10% and 90% of the stable photocurrent along the rise and fall. Under 254 nm light, the UV photodiode of this embodiment exhibits a fast response speed, with a rise time of 1.31 s and a decay time of 2.09 s.

[0048] The preparation process of the present invention is based on the following three points: (a) the atomic radius of fluorine (F) and oxygen (O) is close; (b) the positive monovalent fluoride ion (F + ) has 6 electrons in its outermost shell, the same number as the outermost electrons of an oxygen atom; (c) the monovalent fluoride ion (F + ) is an available ion source for the ion implanter. Using the above three points (a) + (b) + (c), the ion implantation technology is used to implant the monovalent fluoride ion (F + ) to replace β-Ga 2 O 3 When the fluoride ion (F + ) replaces oxygen (O), and because it is positively charged, it can further attract electrons bound by existing "Ga-O" bonds at other positions, thereby forming holes on existing "Ga-O" bonds at other positions. + ) plays the role of acceptor impurities.

[0049] The present invention itself is non-doped β-Ga 2 O 3 The sample shows an electron carrier concentration of 1.9 × 10 17 cm -3 The main reason for the n-type electrical property is that oxygen vacancies are formed during the epitaxial growth of the sample, which leads to the n-type electrical property. The present invention specifically uses an optimized ion implantation angle, which also makes the implanted fluorine ions (F + ) can hit the oxygen vacancies more accurately and fill the oxygen vacancies better. That is, the oblique angle incident not only realizes the substitution of O atoms, but also fills the original O vacancies, and also avoids the "self-compensation" effect of O vacancies on the already formed holes to the greatest extent, resulting in a decrease in hole concentration. The p-type electrical properties are enhanced in many ways.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a p-type gallium oxide thin film by fluorine ion implantation, characterized in that: The following steps are involved: Step 1, pretreating the non-doped single crystal β-Ga2O3 film; Step 2, injecting positive monovalent fluorine ions into the set area of ​​the pretreated non-doped single crystal β-Ga2O3 film. During the injection process, the injection ion source is positive monovalent fluorine ions, the injection angle is 24°, and the injection dose is 6 × 10 16 ~9 × 10 19 ions / cm 2 .

2. The method for preparing a p-type gallium oxide thin film by fluorine ion implantation according to claim 1, characterized in that: In step 1, the non-doped single crystal β-Ga2O3 film is a film obtained by MOCVD outer edge growth.

3. The method for preparing a p-type gallium oxide thin film by fluorine ion implantation according to claim 1, characterized in that: In step 1, the non-doped β-Ga2O3 film is of n-type conductivity, with a film thickness of 700 nm and a Hall electron carrier concentration of 1.9 × 10 17 cm -3 .

4. The method for preparing a p-type gallium oxide thin film by fluorine ion implantation according to claim 1, characterized in that: In step 1, the pretreatment process is to clean the film with an organic solvent and deionized water, and then blow dry the cleaned film to obtain a pretreated non-doped single crystal β-Ga2O3 film.

5. The method for preparing a p-type gallium oxide thin film by fluorine ion implantation according to claim 1, characterized in that: In step 2, during the injection process, the injection energy is 45 kV, the injection current is 30 μA, and the injection time is 30 min.

6. The method for preparing a p-type gallium oxide thin film by fluorine ion implantation according to claim 1, characterized in that: In step 2, the non-doped area is shielded by a mask plate, the mask plate exposes the set area, and doping ions are injected into the set area.

7. A p-type gallium oxide thin film prepared by the preparation method according to any one of claims 1 to 6 using fluorine ion implantation, characterized in that: The p-type gallium oxide film is divided into a doped region and a non-doped region, wherein the doped region is p-type β-Ga2O3 doped with positive monovalent fluoride ions, and the non-doped region is non-doped n-type β-Ga2O3.

8. A method for preparing an ultraviolet photodiode, characterized in that: Obtain the p-type gallium oxide film as described in claim 7, prepare a gold-aluminum electrode on the doped area, and prepare a magnesium-aluminum electrode on the non-doped area.

9. An ultraviolet photodiode prepared by the preparation method according to claim 8, characterized in that: It comprises the p-type gallium oxide film as described in claim 7, wherein the doped region of the p-type gallium oxide film is a circular region in the middle of the p-type gallium oxide film, and the region outside the circular region is a non-doped region; a gold-aluminum electrode is arranged at the center of the doped region; and two magnesium-aluminum electrodes are arranged in the non-doped region, and the two magnesium-aluminum electrodes are symmetrical with respect to the gold-aluminum electrode.

10. The ultraviolet photodiode according to claim 9, characterized in that: The gold-aluminum electrode is a double-layer electrode, in which gold is in the lower layer and aluminum is in the upper layer; the magnesium-aluminum electrode is a magnesium-aluminum alloy.

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