Ultraviolet photoelectric detector and its preparation method and application

Abstract

The present invention discloses an ultraviolet photodetector and its preparation method and application. The ultraviolet photodetector includes the following structures: a substrate layer; a GaN semiconductor layer, the GaN semiconductor layer is arranged on the upper surface of the substrate layer; an N-type semiconductor layer, the N-type semiconductor layer is arranged on the upper surface of the GaN semiconductor layer; an ohmic electrode contact layer, the ohmic electrode contact layer is arranged on the upper surface of the GaN semiconductor layer and is separated from the N-type semiconductor layer; an N-type electrode layer, the N-type electrode layer is arranged on the upper surface of the N-type semiconductor layer. The ultraviolet photodetector of the present invention has a built-in electric field, which can generate a stable photocurrent without an external bias, which makes the ultraviolet photodetector of the present invention not only have the characteristics of fast response, but also have the characteristics of self-driving.

Description

Technical Field

[0001] The present invention relates to the technical field related to photoelectric detectors, and in particular to an ultraviolet photoelectric detector and a preparation method and application thereof. Background Art

[0002] GaN-based self-driven photovoltaic devices have established an important position in many fields, such as combustion monitoring, industrial monitoring, missile plume detection, etc., due to their low power consumption, versatility and excellent working ability in extreme environments. In addition, ZnWO4 has attracted extensive attention from many scholars due to its unique physical and chemical properties and applications in photocatalysis, lithium-ion batteries and other fields.

[0003] As an N-type semiconductor material, ZnWO4 has different sizes and shapes, such as powder and film, which can realize potential applications in different scientific fields, but its application in the field of photoelectric detection has rarely been reported. In recent years, although ZnWO4 has been prepared by hydrothermal, ion beam sputtering, ultrasonic spray pyrolysis and other methods, in fact, these methods still have some disadvantages, such as complex operation, high cost, and inability to prepare on a large scale.

[0004] Based on this, there is an urgent need for a new ZnWO4-based photodetector with excellent photoelectric performance, as well as a new high-efficiency and low-cost ZnWO4 preparation method. Summary of the invention

[0005] The first technical problem to be solved by the present invention is:

[0006] An ultraviolet photodetector is provided.

[0007] The second technical problem to be solved by the present invention is:

[0008] A method for preparing the ultraviolet photoelectric detector is provided.

[0009] The third technical problem to be solved by the present invention is:

[0010] Application of the ultraviolet photodetector.

[0011] In order to solve the first technical problem, the technical solution adopted by the present invention is:

[0012] An ultraviolet photodetector comprises the following structure:

[0013] substrate layer;

[0014] A GaN semiconductor layer, wherein the GaN semiconductor layer is disposed on the upper surface of the substrate layer;

[0015] An N-type semiconductor layer, the N-type semiconductor layer is disposed on an upper surface of the GaN semiconductor layer;

[0016] An ohmic electrode contact layer, the ohmic electrode contact layer is disposed on the upper surface of the GaN semiconductor layer and is separated from the N-type semiconductor layer;

[0017] An N-type electrode layer is disposed on the upper surface of the N-type semiconductor layer.

[0018] According to the embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0019] 1. The ultraviolet photodetector of the present invention adopts a vertical structure, and two electrodes are respectively arranged on both sides of the GaN semiconductor layer, so that the current almost entirely flows vertically through the GaN semiconductor layer, and very little current flows laterally, thereby avoiding the current crowding problem of the lateral structure, shortening the carrier crossing distance, and improving the detector response speed and power.

[0020] 2. The ultraviolet photodetector of the present invention is a homogeneous heterojunction photodetector, in which an ohmic contact is formed between the N-type electrode contact layer and the N-type semiconductor layer to construct a built-in electric field. Under the strong built-in electric field of the ultraviolet photodetector of the present invention, electron-hole pairs can be separated quickly and efficiently.

[0021] 3. The ultraviolet photodetector of the present invention has a built-in electric field and can generate a stable photocurrent without an external bias voltage, which makes the ultraviolet photodetector of the present invention not only have the characteristics of fast response, but also have the characteristics of self-driving.

[0022] 4. The ultraviolet photodetector of the present invention has a self-driving characteristic, so that the ultraviolet photodetector of the present invention has a significant self-powered characteristic and can significantly reduce power consumption during operation.

[0023] According to an embodiment of the present invention, the N-type semiconductor layer includes a ZnWO4 layer. The present invention proposes for the first time the application of ZnWO4 material in photodetectors, providing a new idea for the diversified research and development of photovoltaic devices.

[0024] According to an embodiment of the present invention, the thickness of the GaN semiconductor layer is 4 μm to 6 μm.

[0025] According to an embodiment of the present invention, the GaN semiconductor layer is a hydrophilic GaN semiconductor layer. The GaN semiconductor layer is treated to be hydrophilic so as to enhance the contact between the GaN and the precursor solution of the N-type semiconductor layer.

[0026] According to an embodiment of the present invention, the thickness of the N-type semiconductor layer is 10-200 nm.

[0027] According to one embodiment of the present invention, the thickness of the ohmic electrode contact layer is 50 nm to 200 nm.

[0028] According to one embodiment of the present invention, the carrier concentration of the GaN semiconductor layer is 1×10 15 cm -3 ~1×10 18 cm -3 .

[0029] According to some embodiments of the present invention, the substrate includes at least one of a sapphire substrate and a silicon substrate.

[0030] According to one embodiment of the present invention, the ohmic electrode contact layer includes at least one of a Ti / Al electrode layer and a Ti / Al / Ti / Au electrode layer.

[0031] In order to solve the second technical problem, the technical solution adopted by the present invention is:

[0032] A method for preparing the ultraviolet photodetector comprises the following steps:

[0033] S1 epitaxially grows the GaN semiconductor layer on the substrate layer;

[0034] S2: preparing a precursor solution, spin-coating the precursor solution on the upper surface of the GaN semiconductor layer, and annealing to form an N-type semiconductor layer;

[0035] S3: preparing the N-type electrode layer on the upper surface of the N-type semiconductor layer;

[0036] S4: preparing the ohmic contact electrode layer on the upper surface of the GaN semiconductor layer to obtain the ultraviolet photodetector.

[0037] According to the embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0038] The preparation method of the present invention is low in cost, efficient and reliable, and has good film-forming effect, so that the prepared heterojunction ultraviolet light detector has stable light response, high light-to-dark current ratio and unique self-powered characteristics.

[0039] According to an embodiment of the present invention, step S1 further includes the steps of cleaning and drying the prepared GaN semiconductor layer. The cleaning process is as follows: first, 0.5 to 1 cm 2The GaN semiconductor layer is ultrasonically cleaned with acetone, ethanol and deionized water in sequence, and each step lasts for 10 to 15 minutes; then the GaN semiconductor layer is hydrophilically treated in a UV ozone cleaning machine to enhance the contact between GaN and the ZnWO4 precursor solution, and the hydrophilic treatment time is 15 to 30 minutes.

[0040] According to some embodiments of the present invention, in step S2, the spin coating speed is set to 2000-4000 rpm, and the time is 20-40 s.

[0041] According to one embodiment of the present invention, in step S2, the annealing temperature is 400-600° C., and the holding time is 1-4 hours.

[0042] According to one embodiment of the present invention, in step S2, the precursor solution is a ZnWO4 solution prepared by a sol-gel method. The present invention uses a sol-gel method to prepare a ZnWO4 precursor solution, and then prepares a ZnWO4 thin film by thermal annealing. This makes the preparation cost low, efficient and reliable, and the film-forming effect good.

[0043] According to one embodiment of the present invention, the specific steps of preparing the precursor solution of the ZnWO4 layer are as follows:

[0044] A1. First, weigh 1-5g zinc acetate, 1-10g ammonium metatungstate, and 0.1-1g polyvinyl alcohol (PVA) on an electronic balance.

[0045] A2. Add 0.1-1 g PVA into a beaker containing 50-200 mL deionized water, and place it on a magnetic stirrer. Set the temperature to 80-120°C and the speed to 400-700 rpm. Heat and stir for 1-2 hours. The resulting solution is recorded as A.

[0046] A3. Add 1-5 g zinc acetate into a beaker containing 50-200 mL deionized water and 1-10 mL glacial acetic acid and stir thoroughly. The resulting solution is recorded as B.

[0047] A4. Add 1-10 g of ammonium metatungstate into a beaker containing 50-200 mL of deionized water and stir thoroughly. The resulting solution is recorded as C.

[0048] A5. Then, solution B and solution C are added to solution A together, and the resulting solution is recorded as D;

[0049] A6. Set the parameters of the magnetic stirrer to a temperature of 50-100°C and a rotation speed of 400-700 rpm. Place solution D on the magnetic stirrer and heat and stir for 0.5-1 h. The solution obtained in this way is a ZnWO4 precursor solution.

[0050] Another aspect of the present invention also relates to the application of the ultraviolet photoelectric detector in missile warning, including the ultraviolet photoelectric detector as described in the first embodiment. Since the application adopts all the technical solutions of the ultraviolet photoelectric detector of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0051] Another aspect of the present invention also relates to the application of the ultraviolet photoelectric detector in ultraviolet radiation monitoring. It includes the ultraviolet photoelectric detector as described in the embodiment of the first aspect above. Since the application adopts all the technical solutions of the ultraviolet photoelectric detector of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0052] Another aspect of the present invention also relates to the application of the ultraviolet photodetector in optical communication, including the ultraviolet photodetector as described in the first embodiment. Since the application adopts all the technical solutions of the ultraviolet photodetector of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0053] Another aspect of the present invention also relates to the application of the ultraviolet photodetector in the field of photoelectric detection, including the ultraviolet photodetector as described in the first embodiment. Since the application adopts all the technical solutions of the ultraviolet photodetector of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0054] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0056] Figure 1 Schematic diagram of the structure of the ultraviolet detector prepared in Examples 1 to 4.

[0057] Figure 2 This is a test diagram of the photoelectric performance of the ultraviolet detector prepared in Example 1.

[0058] Figure 3 This is the spectrum diagram of the ultraviolet detector of Example 1.

[0059] Figure 4 This is a test diagram of the photoelectric performance of the ultraviolet detector of Example 2.

[0060] Figure 5The responsiveness and external quantum efficiency spectrum of the ultraviolet detector of Example 3.

[0061] Figure 6 This is a current-time curve of the ultraviolet detector of Example 4 under 0V bias and 360nm ultraviolet light irradiation.

[0062] Reference numerals:

[0063] 100 - substrate layer, 200 - GaN semiconductor layer, 300 - N-type semiconductor layer, 400 - N-type electrode layer, 500 - ohmic electrode contact layer. DETAILED DESCRIPTION

[0064] Embodiments of the present invention are described in detail below, examples of the above embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0065] In the description of the present invention, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0066] In the description of the present invention, it should be understood that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship 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 should not be understood as a limitation on the present invention.

[0067] In the description of the present invention, it should be noted that, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0068] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0069] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0070] Example 1

[0071] This embodiment provides an ultraviolet photodetector, such as Figure 1 As shown, it includes the following structures:

[0072] Substrate layer 100;

[0073] A GaN semiconductor layer 200, wherein the GaN semiconductor layer 200 is disposed on the upper surface of the substrate layer 100;

[0074] An N-type semiconductor layer 300 , wherein the N-type semiconductor layer 300 is disposed on an upper surface of the GaN semiconductor layer 200 ;

[0075] An ohmic electrode contact layer 500 , wherein the ohmic electrode contact layer 500 is disposed on the upper surface of the GaN semiconductor layer 200 and is separated from the N-type semiconductor layer 300 ;

[0076] The N-type electrode layer 400 is disposed on the upper surface of the N-type semiconductor layer 300 .

[0077] In this embodiment, the substrate layer 100 is a sapphire substrate with an area of ​​1 cm 2 ;

[0078] The GaN semiconductor layer 200 has a thickness of 4 μm. The GaN semiconductor layer is a GaN layer, and its carrier concentration range at room temperature is 4.3×10 17 cm -3 ;

[0079] The thickness of the N-type semiconductor layer 300 is 200 nm, and the N-type semiconductor layer is a ZnWO4 layer;

[0080] The thickness of the ohmic electrode contact layer 500 is 100 nm, and the ohmic electrode contact layer is a Ti / Al electrode layer;

[0081] The thickness of the N-type electrode layer 400 is 100 nm, and the N-type electrode layer is an Ag electrode layer.

[0082] This embodiment also provides a method for preparing the above-mentioned ultraviolet photoelectric detector, comprising:

[0083] (1) epitaxially growing a GaN thin film on the substrate layer 100 to form a GaN semiconductor layer 200;

[0084] (2) The GaN semiconductor layer prepared in step (1) is ultrasonically cleaned with acetone, ethanol and deionized water in turn, each step lasting 15 minutes, and then the GaN semiconductor layer is hydrophilized in a UV ozone cleaning machine to enhance the contact between GaN and the ZnWO4 precursor solution. The hydrophilic treatment time is 20 minutes. The ZnWO4 precursor solution is prepared by a sol-gel method and spin-coated and annealed on the upper surface of the GaN film to prepare an N-type semiconductor layer, i.e., a ZnWO4 layer. The spin coating speed is 3000 rpm and the time is 30 seconds. The annealing temperature is 500°C and the time is 1 hour;

[0085] (3) Preparing a Ag electrode layer on the upper surface of the N-type semiconductor layer 300 prepared in step (2) by vacuum evaporation;

[0086] (4) A Ti / Al electrode layer is prepared on the upper surface of the GaN semiconductor layer 200 by vacuum evaporation.

[0087] The preparation process of the ZnWO4 precursor solution in the above step (2) of this example is:

[0088] (A) First, weigh 1g zinc acetate, 1.5g ammonium metatungstate, and 0.5g polyvinyl alcohol (PVA) on an electronic balance;

[0089] (B) 0.5 g of PVA was added to a beaker containing 50 mL of deionized water, and the beaker was placed on a magnetic stirrer. The temperature and speed of the magnetic stirrer were set to 80 °C and 500 rpm, and the mixture was heated and stirred for 1 h. The resulting solution was recorded as A.

[0090] (C) Add 1 g of zinc acetate into a beaker containing 50 mL of deionized water and 10 mL of glacial acetic acid and stir thoroughly. The resulting solution is recorded as B.

[0091] (D) 1.5 g of ammonium metatungstate was added to a beaker containing 50 mL of deionized water and stirred thoroughly. The resulting solution was recorded as C.

[0092] (E) Then, solution B and solution C are added to solution A together, and the resulting solution is recorded as D;

[0093] (F) The parameters of the magnetic stirrer are set to a temperature of 80°C and a rotation speed of 500 rpm. Solution D is placed on the magnetic stirrer and heated and stirred for 0.5 h. The solution obtained in this way is a ZnWO4 precursor solution.

[0094] Example 2

[0095] The difference between Example 2 and Example 1 is that the thickness of the N-type semiconductor layer 300 (ZnWO4 layer) is different. The thickness of the ZnWO4 layer in Example 1 is 200nm, and the thickness of the ZnWO4 layer in Example 2 is 100nm. The ultraviolet photodetector prepared in Example 2 has a thin film layer, which does not form a good heterojunction with the GaN semiconductor layer 200, resulting in a weak built-in electric field. Its light-to-dark current ratio (301) at 0V is lower than that of Example 1 (524), which can be specifically determined by Figure 2 and Figure 4 Learn.

[0096] This embodiment provides an ultraviolet photodetector, such as Figure 1 As shown, it includes the following structures:

[0097] Substrate layer 100;

[0098] A GaN semiconductor layer 200, wherein the GaN semiconductor layer 200 is disposed on the upper surface of the substrate layer 100;

[0099] An N-type semiconductor layer 300 , wherein the N-type semiconductor layer 300 is disposed on an upper surface of the GaN semiconductor layer 200 ;

[0100] An ohmic electrode contact layer 500 , wherein the ohmic electrode contact layer 500 is disposed on the upper surface of the GaN semiconductor layer 200 and is separated from the N-type semiconductor layer 300 ;

[0101] The N-type electrode layer 400 is disposed on the upper surface of the N-type semiconductor layer 300 .

[0102] In this embodiment, the substrate layer 100 is a sapphire substrate with an area of ​​1 cm 2 ;

[0103] The GaN semiconductor layer 200 has a thickness of 4 μm. The GaN semiconductor layer is a GaN layer, and its carrier concentration range at room temperature is 4.3×10 17 cm -3 ;

[0104] The thickness of the N-type semiconductor layer 300 is 100 nm, and the N-type semiconductor layer is a ZnWO4 layer;

[0105] The thickness of the ohmic electrode contact layer 500 is 100 nm, and the ohmic electrode contact layer is a Ti / Al electrode layer;

[0106] The thickness of the N-type electrode layer 400 is 100 nm, and the N-type electrode layer is an Ag electrode layer.

[0107] This embodiment also provides a method for preparing the above-mentioned ultraviolet photoelectric detector, comprising:

[0108] (1) epitaxially growing a GaN thin film on the substrate layer 100 to form a GaN semiconductor layer 200;

[0109] (2) The GaN semiconductor layer prepared in step (1) is ultrasonically cleaned with acetone, ethanol and deionized water in turn, each step lasting 15 minutes, and then the GaN semiconductor layer is hydrophilized in a UV ozone cleaning machine to enhance the contact between GaN and the ZnWO4 precursor solution. The hydrophilic treatment time is 20 minutes. The ZnWO4 precursor solution is prepared by a sol-gel method and spin-coated and annealed on the upper surface of the GaN film to prepare an N-type semiconductor layer, i.e., a ZnWO4 layer. The spin coating speed is 3000 rpm and the time is 30 seconds. The annealing temperature is 500°C and the time is 1 hour;

[0110] (3) Preparing a Ag electrode layer on the upper surface of the N-type semiconductor layer 300 prepared in step (2) by vacuum evaporation;

[0111] (4) A Ti / Al electrode layer is prepared on the upper surface of the GaN semiconductor layer 200 by vacuum evaporation.

[0112] The preparation process of the ZnWO4 precursor solution in the above step (2) of this example is:

[0113] (A) First, weigh 1g zinc acetate, 1.5g ammonium metatungstate, and 0.5g polyvinyl alcohol (PVA) on an electronic balance;

[0114] (B) 0.5 g of PVA was added to a beaker containing 50 mL of deionized water, and the beaker was placed on a magnetic stirrer. The temperature and speed of the magnetic stirrer were set to 80 °C and 500 rpm, and the mixture was heated and stirred for 1 h. The resulting solution was recorded as A.

[0115] (C) Add 1 g of zinc acetate into a beaker containing 50 mL of deionized water and 10 mL of glacial acetic acid and stir thoroughly. The resulting solution is recorded as B.

[0116] (D) 1.5 g of ammonium metatungstate was added to a beaker containing 50 mL of deionized water and stirred thoroughly. The resulting solution was recorded as C.

[0117] (E) Then, solution B and solution C are added to solution A together, and the resulting solution is recorded as D;

[0118] (F) The parameters of the magnetic stirrer are set to a temperature of 80°C and a rotation speed of 500 rpm. Solution D is placed on the magnetic stirrer and heated and stirred for 0.5 h. The solution obtained in this way is a ZnWO4 precursor solution.

[0119] Example 3

[0120] The difference between Example 3 and Example 1 is that the concentration of the ZnWO4 precursor solution is different and the amount of solute in the solution is different. The ZnWO4 precursor solution of Example 1 includes the following raw materials: 1g zinc acetate, 1.5g ammonium metatungstate, and 0.5g polyvinyl alcohol; the ZnWO4 precursor solution of Example 3 includes the following raw materials: 1.6g zinc acetate, 1.2g ammonium metatungstate, and 0.3g polyvinyl alcohol.

[0121] This embodiment provides an ultraviolet photodetector, such as Figure 1 As shown, it includes the following structures:

[0122] Substrate layer 100;

[0123] A GaN semiconductor layer 200, wherein the GaN semiconductor layer 200 is disposed on the upper surface of the substrate layer 100;

[0124] An N-type semiconductor layer 300 , wherein the N-type semiconductor layer 300 is disposed on an upper surface of the GaN semiconductor layer 200 ;

[0125] An ohmic electrode contact layer 500 , wherein the ohmic electrode contact layer 500 is disposed on the upper surface of the GaN semiconductor layer 200 and is separated from the N-type semiconductor layer 300 ;

[0126] The N-type electrode layer 400 is disposed on the upper surface of the N-type semiconductor layer 300 .

[0127] In this embodiment, the substrate layer 100 is a sapphire substrate with an area of ​​1 cm 2 ;

[0128] The GaN semiconductor layer 200 has a thickness of 4 μm. The GaN semiconductor layer is a GaN layer, and its carrier concentration range at room temperature is 4.3×10 17 cm -3 ;

[0129] The thickness of the N-type semiconductor layer 300 is 200 nm, and the N-type semiconductor layer is a ZnWO4 layer;

[0130] The thickness of the ohmic electrode contact layer 500 is 100 nm, and the ohmic electrode contact layer is a Ti / Al electrode layer;

[0131] The thickness of the N-type electrode layer 400 is 100 nm, and the N-type electrode layer is an Ag electrode layer.

[0132] This embodiment also provides a method for preparing the above-mentioned ultraviolet photoelectric detector, comprising:

[0133] (1) epitaxially growing a GaN thin film on the substrate layer 100 to form a GaN semiconductor layer 200;

[0134] (2) The GaN semiconductor layer prepared in step (1) is ultrasonically cleaned with acetone, ethanol and deionized water in turn, each step lasting 15 minutes, and then the GaN semiconductor layer is hydrophilized in a UV ozone cleaning machine to enhance the contact between GaN and the ZnWO4 precursor solution. The hydrophilic treatment time is 20 minutes. The ZnWO4 precursor solution is prepared by a sol-gel method and spin-coated and annealed on the upper surface of the GaN film to prepare an N-type semiconductor layer, i.e., a ZnWO4 layer. The spin coating speed is 3000 rpm and the time is 30 seconds. The annealing temperature is 500°C and the time is 1 hour;

[0135] (3) Preparing a Ag electrode layer on the upper surface of the N-type semiconductor layer 300 prepared in step (2) by vacuum evaporation;

[0136] (4) A Ti / Al electrode layer is prepared on the upper surface of the GaN semiconductor layer 200 by vacuum evaporation.

[0137] As a preferred embodiment of the present invention, the preparation process of the ZnWO4 precursor solution in the above step (2) is as follows:

[0138] (A) First, weigh 1.6g zinc acetate, 1.2g ammonium metatungstate, and 0.3g polyvinyl alcohol (PVA) on an electronic balance;

[0139] (B) 0.3 g of PVA was added to a beaker containing 50 mL of deionized water, and the beaker was placed on a magnetic stirrer. The temperature and speed of the magnetic stirrer were set to 80°C and 500 rpm, and the mixture was heated and stirred for 1 h. The resulting solution was recorded as A.

[0140] (C) Add 1.6 g of zinc acetate into a beaker containing 80 mL of deionized water and 20 mL of glacial acetic acid and stir thoroughly. The resulting solution is recorded as B.

[0141] (D) 1.2 g of ammonium metatungstate was added to a beaker containing 80 mL of deionized water and stirred thoroughly. The resulting solution was recorded as C.

[0142] (E) Then, solution B and solution C are added to solution A together, and the resulting solution is recorded as D;

[0143] (F) The parameters of the magnetic stirrer are set to a temperature of 90°C and a rotation speed of 500 rpm. Solution D is placed on the magnetic stirrer and heated and stirred for 1.5 h. The solution obtained in this way is a ZnWO4 precursor solution.

[0144] Example 4

[0145] The difference between Example 4 and Example 1 is that the annealing temperature of ZnWO4 is different. The annealing temperature of Example 1 is 500°C, while the annealing temperature of Example 4 is 600°C.

[0146] This embodiment provides an ultraviolet photodetector, such as Figure 1 As shown, it includes the following structures:

[0147] Substrate layer 100;

[0148] A GaN semiconductor layer 200, wherein the GaN semiconductor layer 200 is disposed on the upper surface of the substrate layer 100;

[0149] An N-type semiconductor layer 300 , wherein the N-type semiconductor layer 300 is disposed on an upper surface of the GaN semiconductor layer 200 ;

[0150] An ohmic electrode contact layer 500 , wherein the ohmic electrode contact layer 500 is disposed on the upper surface of the GaN semiconductor layer 200 and is separated from the N-type semiconductor layer 300 ;

[0151] The N-type electrode layer 400 is disposed on the upper surface of the N-type semiconductor layer 300 .

[0152] In this embodiment, the substrate layer 100 is a sapphire substrate with an area of ​​1 cm 2 ;

[0153] The GaN semiconductor layer 200 has a thickness of 4 μm. The GaN semiconductor layer is a GaN layer, and its carrier concentration range at room temperature is 4.3×10 17 cm -3 ;

[0154] The thickness of the N-type semiconductor layer 300 is 200 nm, and the N-type semiconductor layer is a ZnWO4 layer;

[0155] The thickness of the ohmic electrode contact layer 500 is 100 nm, and the ohmic electrode contact layer is a Ti / Al electrode layer;

[0156] The thickness of the N-type electrode layer 400 is 100 nm, and the N-type electrode layer is an Ag electrode layer.

[0157] This embodiment provides a method for preparing the above-mentioned ultraviolet photodetector, comprising:

[0158] (1) epitaxially growing a GaN thin film on the substrate layer 100 to form a GaN semiconductor layer 200;

[0159] (2) The GaN semiconductor layer prepared in step (1) is ultrasonically cleaned with acetone, ethanol and deionized water in turn, each step lasting 15 minutes, and then the GaN semiconductor layer is hydrophilized in a UV ozone cleaning machine to enhance the contact between GaN and the ZnWO4 precursor solution. The hydrophilic treatment time is 20 minutes. The ZnWO4 precursor solution is prepared by a sol-gel method and spin-coated and annealed on the upper surface of the GaN film to prepare an N-type semiconductor layer, i.e., a ZnWO4 layer. The spin coating speed is 3000 rpm and the time is 30 seconds. The annealing temperature is 600°C and the time is 1 hour;

[0160] (3) Preparing a Ag electrode layer on the upper surface of the N-type semiconductor layer 300 prepared in step (2) by vacuum evaporation;

[0161] (4) A Ti / Al electrode layer is prepared on the upper surface of the GaN semiconductor layer 200 by vacuum evaporation.

[0162] As a preferred embodiment of the present invention, the preparation process of the ZnWO4 precursor solution in the above step (2) is as follows:

[0163] (A) First, weigh 1g zinc acetate, 1.5g ammonium metatungstate, and 0.5g polyvinyl alcohol (PVA) on an electronic balance;

[0164] (B) 0.5 g of PVA was added to a beaker containing 50 mL of deionized water, and the beaker was placed on a magnetic stirrer. The temperature and speed of the magnetic stirrer were set to 80 °C and 500 rpm, and the mixture was heated and stirred for 1 h. The resulting solution was recorded as A.

[0165] (C) Add 1 g of zinc acetate into a beaker containing 50 mL of deionized water and 10 mL of glacial acetic acid and stir thoroughly. The resulting solution is recorded as B.

[0166] (D) 1.5 g of ammonium metatungstate was added to a beaker containing 50 mL of deionized water and stirred thoroughly. The resulting solution was recorded as C.

[0167] (E) Then, solution B and solution C are added to solution A together, and the resulting solution is recorded as D;

[0168] (F) The parameters of the magnetic stirrer are set to a temperature of 80°C and a rotation speed of 500 rpm. Solution D is placed on the magnetic stirrer and heated and stirred for 0.5 h. The solution obtained in this way is a ZnWO4 precursor solution.

[0169] Comparative Example

[0170] The difference between the comparative example and the embodiment 1 is that the structures are different: the embodiment 1 is an N-type semiconductor layer, and the comparative example 1 is a P-type semiconductor layer.

[0171] This comparative example provides an ultraviolet photoelectric detector, comprising the following structure:

[0172] Substrate layer 100;

[0173] A GaN semiconductor layer 200, wherein the GaN semiconductor layer 200 is disposed on the upper surface of the substrate layer 100;

[0174] A P-type semiconductor layer, the P-type semiconductor layer is disposed on the upper surface of the GaN semiconductor layer 200;

[0175] An ohmic electrode contact layer 500 , wherein the ohmic electrode contact layer 500 is disposed on the upper surface of the GaN semiconductor layer 200 and is separated from the N-type semiconductor layer 300 ;

[0176] The N-type electrode layer 400 is disposed on the upper surface of the N-type semiconductor layer 300 .

[0177] In this embodiment, the substrate layer 100 is a sapphire substrate with an area of ​​1 cm 2 ;

[0178] The GaN semiconductor layer 200 has a thickness of 4 μm. The GaN semiconductor layer is a GaN layer, and its carrier concentration range at room temperature is 4.3×10 17 cm -3 ;

[0179] The thickness of the P-type semiconductor layer 300 is 200 nm, and the P-type semiconductor layer is a P-GaN layer;

[0180] The thickness of the ohmic electrode contact layer 500 is 100 nm, and the ohmic electrode contact layer is a Ti / Al electrode layer;

[0181] The thickness of the N-type electrode layer 400 is 100 nm, and the N-type electrode layer is an Ag electrode layer.

[0182] This embodiment also provides a method for preparing the above-mentioned ultraviolet photoelectric detector, comprising:

[0183] (1) epitaxially growing a GaN thin film on the substrate layer 100 to form a GaN semiconductor layer 200;

[0184] (2) The GaN semiconductor layer prepared in step (1) is ultrasonically cleaned with acetone, ethanol and deionized water in sequence, each step lasting 15 minutes, and then the GaN semiconductor layer is hydrophilized in a UV ozone cleaning machine for 20 minutes.

[0185] (3) a P-type semiconductor layer is prepared on the upper surface of the GaN semiconductor layer, and a Ag electrode layer is prepared on the upper surface of the P-type semiconductor layer by vacuum evaporation;

[0186] (4) A Ti / Al electrode layer is prepared on the upper surface of the GaN semiconductor layer 200 by vacuum evaporation.

[0187] Performance Test:

[0188] The photoelectric performance of the ultraviolet detectors prepared in Examples 1 to 4 was tested, and the test results were as follows: Figures 2 to 6 shown.

[0189] Figure 2 The photoelectric performance test diagram of the ultraviolet detector prepared in Example 1 is shown in FIG. Figure 2 It can be seen that the light / dark current ratio of the prepared ultraviolet photodetector is 524 under 0V bias and 360nm ultraviolet light irradiation.

[0190] Figure 3 is the spectrum diagram of the ultraviolet detector of Example 1. Figure 3 It can be seen that the prepared UV photodetector generates a peak photocurrent of about 0.4 μA at 0 V bias and 360 nm.

[0191] Figure 4 This is a test diagram of the photoelectric performance of the ultraviolet detector of Example 2. Figure 4 It can be seen that the light / dark current ratio of the prepared ultraviolet photodetector is 301 under 0V bias and 360nm ultraviolet light irradiation.

[0192] Figure 5 The following is a graph showing the responsivity and external quantum efficiency of the ultraviolet detector of Example 3. Figure 5 It can be seen that the device has a responsivity of 22.7 mA / W under 0 V bias and 360 nm ultraviolet light irradiation, and an external quantum efficiency of 7.8%, showing excellent photoelectric performance.

[0193] Figure 6 The current-time curve of the UV detector of Example 4 under 0V bias and 360nm UV light irradiation. Figure 6 It can be seen that the prepared UV photodetector generates a stable light / dark current (≈0.3μA) in each optical switching cycle under 0V bias and 360nm UV light irradiation.

[0194] The above are only embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An ultraviolet photoelectric detector, characterized in that: Includes the following structures: substrate layer; A GaN semiconductor layer, wherein the GaN semiconductor layer is disposed on the upper surface of the substrate layer; An N-type semiconductor layer, the N-type semiconductor layer is disposed on an upper surface of the GaN semiconductor layer; An ohmic electrode contact layer, the ohmic electrode contact layer is disposed on the upper surface of the GaN semiconductor layer and is separated from the N-type semiconductor layer; An N-type electrode layer, the N-type electrode layer is disposed on the upper surface of the N-type semiconductor layer; The N-type semiconductor layer includes a ZnWO4 layer; The GaN semiconductor layer is a hydrophilic GaN semiconductor layer; The steps for preparing the precursor solution of the N-type semiconductor layer are as follows: A1 first weighs 1-5g of zinc acetate, 1-10g of ammonium metatungstate, and 0.1-1g of polyvinyl alcohol on an electronic balance; A2: Add 0.1-1 g PVA into a beaker containing 50-200 mL deionized water and place it on a magnetic stirrer. Set the temperature to 80-120 °C and the speed to 400-700 rpm. Heat and stir for 1-2 h. The resulting solution is recorded as A. A3: Add 1-5 g zinc acetate into a beaker containing 50-200 mL deionized water and 1-10 mL glacial acetic acid and stir thoroughly. The resulting solution is recorded as B. A4: Add 1-10 g of ammonium metatungstate into a beaker containing 50-200 mL of deionized water and stir thoroughly. The resulting solution is recorded as C. A5 then adds solution B and solution C together into solution A, and the resulting solution is recorded as D; The parameters of the A6 magnetic stirrer are set to a temperature of 50-100° C. and a rotation speed of 400-700 rpm. Solution D is placed on the magnetic stirrer and heated and stirred for 0.5-1 h to obtain the precursor solution.

2. The ultraviolet photoelectric detector according to claim 1, characterized in that: The thickness of the GaN semiconductor layer is 4 μm to 6 μm.

3. The ultraviolet photoelectric detector according to claim 1, characterized in that: The thickness of the N-type semiconductor layer is 10-200 nm.

4. The ultraviolet photoelectric detector according to claim 1, characterized in that: The thickness of the ohmic electrode contact layer is 50nm-200nm.

5. A method for preparing an ultraviolet photodetector as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1 epitaxially grows the GaN semiconductor layer on the substrate layer; S2: preparing a precursor solution, spin-coating the precursor solution on the upper surface of the GaN semiconductor layer, and annealing to form an N-type semiconductor layer; S3: preparing the N-type electrode layer on the upper surface of the N-type semiconductor layer; S4 prepares the ohmic electrode contact layer on the upper surface of the GaN semiconductor layer to obtain the ultraviolet photodetector.

6. The method according to claim 5, characterized in that: In step S2, the precursor solution is a ZnWO4 solution prepared by a sol-gel method.

7. The method according to claim 5, characterized in that: In step S2, the annealing temperature is 400-600°C, and the holding time is 1-4 hours.

8. Application of an ultraviolet photoelectric detector as claimed in any one of claims 1 to 4 in the fields of missile early warning, ultraviolet radiation monitoring, optical communication or photoelectric detection.

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