Full-transparent nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector and preparation method and application thereof

Abstract

The invention relates to a full-transparent nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector and a preparation method and application thereof.The solar-blind ultraviolet detector sequentially comprises a flexible substrate, a bottom electrode layer, a NiO thin film layer, a Ga2O3 thin film layer and an upper electrode layer from bottom to top, and the bottom electrode layer, the NiO thin film layer, the Ga2O3 thin film layer and the upper electrode layer are arranged in a step shape; the flexible substrate comprises a PET flexible substrate, and the bottom electrode layer and the upper electrode layer are both BGZO electrode layers. According to the invention, the magnetron sputtering method is adopted, the electrode is grown on the transparent substrate, and proper sputtering power is selected, so that the preparation of the high-performance full-transparent nickel oxide and gallium oxide thin film is realized. Compared with the prior art, the solar blind ultraviolet detector obtained by the invention has self-powered, full-transparent and flexible properties, has the characteristics of portability and wearable performance, and can be better applied to the fields of ultraviolet detection and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device manufacturing process, and in particular to a fully transparent nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector and a preparation method and application thereof. Background Art

[0002] Solar-blind ultraviolet radiation refers to ultraviolet radiation with a wavelength range of 200 to 280 nanometers. Since the ozone layer in the earth's atmosphere almost completely absorbs solar radiation in this specific band, ultraviolet radiation in this band is called solar-blind ultraviolet radiation. Solar-blind ultraviolet detectors have attracted widespread attention due to their high sensitivity and high precision in detecting this specific ultraviolet band. They have important applications in military and civilian fields, such as ozone layer monitoring, flame detection, medical imaging, ultraviolet communications, and missile early warning systems. In recent years, with the increasing public attention to radiation safety and health monitoring, the thinning or depletion of the ozone layer has allowed solar-blind ultraviolet radiation to reach the earth's surface directly. In addition, some special equipment also emits solar-blind ultraviolet radiation. Long-term exposure to this radiation may cause serious health hazards, including increased risk of skin cancer and irreversible blindness. Therefore, there is an urgent need for portable, self-powered, and real-time monitoring systems for solar-blind ultraviolet radiation. In this context, wearable solar-blind ultraviolet detectors have become an important part of optoelectronic technology, which can achieve continuous and real-time monitoring and protection to prevent the hazards of solar-blind ultraviolet radiation. Summary of the invention

[0003] The purpose of the present invention is to provide a fully transparent nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector and its preparation method and application. The nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector has self-powered, fully transparent and flexible properties, and can be applied to wearable devices.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] On the one hand, the present invention provides a fully transparent nickel oxide / gallium oxide PN junction type day-blind ultraviolet detector, which includes, from bottom to top, a flexible substrate, a bottom electrode layer, a NiO thin film layer, a Ga2O3 thin film layer, and an upper electrode layer.

[0006] Preferably, the bottom electrode layer, NiO thin film layer, Ga2O3 thin film layer and upper electrode layer are arranged in a stepped manner, the area of ​​the NiO thin film layer is smaller than that of the bottom electrode layer, the area of ​​the Ga2O3 thin film layer is smaller than that of the NiO thin film layer, and the area of ​​the upper electrode layer is smaller than that of the Ga2O3 thin film layer.

[0007] Preferably, the bottom electrode layer completely covers the flexible substrate.

[0008] Preferably, the flexible substrate is a flexible organic material substrate.

[0009] Further preferably, the flexible substrate is a PET (polyethylene terephthalate) flexible substrate.

[0010] Preferably, the bottom electrode layer and the upper electrode layer are both BGZO (boron gallium co-doped transparent ZnO) electrode layers.

[0011] Preferably, the thickness of the flexible substrate is 0.1-0.5 mm, the thickness of the bottom electrode layer is 100-200 nm, the thickness of the NiO thin film layer is 100-500 nm, the thickness of the Ga2O3 thin film layer is 100-150 nm, and the thickness of the top electrode layer is 100-200 nm.

[0012] Preferably, the Ga2O3 is an n-type semiconductor.

[0013] Preferably, the NiO is a p-type semiconductor.

[0014] In a second aspect, the present invention further provides a method for preparing the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector, comprising the following steps:

[0015] S1, pre-treating the flexible substrate to obtain a pre-treated flexible substrate;

[0016] S2, sputtering a bottom electrode layer on the pretreated flexible substrate by magnetron sputtering;

[0017] S3, sputtering a NiO thin film layer on the bottom electrode layer by using a mask and magnetron sputtering;

[0018] S4, sputtering a Ga2O3 thin film layer on the NiO thin film layer by using a mask and a magnetron sputtering method;

[0019] S5. Sputtering an upper electrode layer on the Ga2O3 thin film layer by using a mask and a magnetron sputtering method to prepare the nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector.

[0020] Preferably, in step S1, the pretreatment process specifically includes the following steps: selecting a flexible substrate and cutting it into a size of 17-22 mm*17-22 mm; ultrasonically treating the cut substrate in methanol, ethanol and deionized water for 5-30 min respectively, and drying it with nitrogen to obtain a clean and dry substrate; sending the cleaned substrate into a magnetron sputtering pretreatment chamber, and evacuating the chamber until the vacuum degree of the magnetron sputtering chamber is 2*10 -6 Torr, introduce argon gas with a flow rate of 10 to 30 sccm and oxygen gas with a flow rate of 5 to 15 sccm, set the sputtering power to 50 to 100 W, and obtain the pretreated substrate after sputtering for 1 to 5 minutes.

[0021] Further preferably, in step S1, the ultrasonic time is 5 minutes.

[0022] Further preferably, in step S1, the argon flow rate is 24.5 sccm, and the oxygen flow rate is 10.5 sccm.

[0023] Further preferably, in step S1, the sputtering power is 50 W and the sputtering time is 2 min.

[0024] Preferably, in step S2, the target material used for the magnetron sputtering is a ZnO ceramic target material co-doped with 1.2-2.4 wt% of boron and 0.1-0.3 wt% of gallium, and the vacuum degree of the magnetron sputtering chamber is 2*10 -6 Torr, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and the baffle is opened after pre-sputtering for 10 to 30 minutes to start formal sputtering, and the formal sputtering time is 15 to 30 minutes.

[0025] Further preferably, in step S2, the argon gas flow rate is 25 sccm.

[0026] Further preferably, in step S2, the tray rotation speed of the magnetron sputtering is ≤5 rad / min.

[0027] Further preferably, in step S2, after pre-sputtering for 10 minutes, the baffle is opened and the formal sputtering is started, and a bottom electrode layer with a thickness of 200 nm is obtained after the sputtering is completed.

[0028] Preferably, in step S3, the rectangular size of the mask is 13-18 mm*10-15 mm, the target material used for the magnetron sputtering is a NiO ceramic target material with a purity greater than 99.99%, and the background vacuum degree of the magnetron sputtering is 2*10 - 6 Torr, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and the baffle is opened after pre-sputtering for 10 to 30 minutes to start formal sputtering, and the formal sputtering time is 110 to 150 minutes.

[0029] Further preferably, in step S3, the size of the mask is 15.5 mm*12.5 mm.

[0030] Further preferably, in step S3, the argon gas flow rate is 15 sccm.

[0031] Further preferably, in step S3, the tray rotation speed of the magnetron sputtering is ≤5 rad / min.

[0032] Further preferably, in step S3, after pre-sputtering for 10 minutes, the baffle is opened and formal sputtering is started, and a NiO thin film layer with a thickness of 350 nm is obtained after the sputtering is completed.

[0033] Preferably, in step S4, the size of the rectangular mask is 10-15 mm*7-12 mm, the target material used for the magnetron sputtering is a Ga2O3 ceramic target material with a purity greater than 99.99%, and the vacuum degree of the magnetron sputtering chamber is 2*10 - 6 Torr, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and the baffle is opened after pre-sputtering for 10 to 30 minutes to start formal sputtering, and the formal sputtering time is 60 to 100 minutes.

[0034] Further preferably, in step S4, the size of the mask is 12.5 mm*9.5 mm.

[0035] Further preferably, in step S4, the argon gas flow rate is 15 sccm.

[0036] Further preferably, in step S4, the rotation speed of the sample tray is ≤5 rad / min.

[0037] Further preferably, in step S4, after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and a Ga2O3 thin film layer with a thickness of 150 nm is obtained after the sputtering is completed.

[0038] Preferably, in step S5, there are 1 to 3 masks, the size of the masks is 3 to 5 mm*3 to 5 mm, the target material used for the magnetron sputtering is a ZnO ceramic target co-doped with 1.2 to 2.4 wt% of boron and 0.1 to 0.3 wt% of gallium, the vacuum degree of the magnetron sputtering chamber is 5 to 7 Pa, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and after 10 to 30 minutes of pre-sputtering, the baffle is opened to start formal sputtering, and the formal sputtering time is 10 to 25 minutes.

[0039] Further preferably, in step S5, the mask plate adopts 2 squares with a size of 4 mm*4 mm.

[0040] Further preferably, in step S5, the mask plate adopts 2 squares with a size of 5 mm*5 mm.

[0041] Further preferably, in step S5, the mask plate adopts 2 squares with a size of 3 mm*3 mm.

[0042] Further preferably, in step S5, the argon gas flow rate is 25 sccm.

[0043] Further preferably, in step S5, the rotation speed of the product tray is ≤5 rad / min.

[0044] Further preferably, in step S5, after pre-sputtering for 10 minutes, the shutter is opened and the formal sputtering is started, and an upper electrode layer with a thickness of 100 nm is obtained after the sputtering is completed.

[0045] In a third aspect, the present invention also provides an application of the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector in the field of preparing wearable devices.

[0046] Preferably, the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector can be used for early warning of direct ultraviolet light caused by the ozone hole.

[0047] Solar-blind UV detectors based on PN junctions have excellent performance because their inherent electric field can autonomously separate electron-hole pairs and can operate without external voltage. This feature not only improves energy efficiency, but also supports long-term use in extreme environments such as the wild and outer space. Among various wide-bandgap semiconductor materials, Ga2O3 is a third-generation semiconductor material. The third-generation semiconductor materials have a large bandgap width, high breakdown strength, and strong radiation resistance, and are naturally suitable for the preparation of high-voltage, high-frequency, and high-power semiconductor devices. Compared with other third-generation semiconductors such as silicon carbide (Eg = 3.3eV) and gallium nitride (Eg = 3.4eV), Ga2O3 has a larger bandgap width (Eg = 4.9eV) and breakdown voltage (8MV / cm, more than 20 times that of Si, more than twice that of SiC and GaN), and the Baliga value of Ga2O3 is as high as 3214.1, which is conducive to the manufacture of high-power, high-density integrated devices. Ga2O3 is a direct bandgap semiconductor material. Its wide bandgap width makes it have high transmittance in the visible light region, which can reach more than 80%. It also has excellent absorption performance in the ultraviolet light band, especially in the solar-blind ultraviolet light region less than 280nm. Its absorption edge is roughly around 250nm, so it is often used to make ultraviolet light detectors, field effect transistors, Schottky diodes, etc. Therefore, Ga2O3 has important application potential in the fields of national defense, aerospace, microwave communications, rail transportation, etc.

[0048] Typically, Ga2O3 is an n-type oxide semiconductor. Researchers have developed pn junction-based solar-blind UV detectors by combining Ga2O3 with a variety of p-type semiconductor materials, such as gallium nitride (GaN), copper iodide (CuI), and nickel oxide (NiO). NiO is a natural p-type oxide semiconductor that has attracted widespread attention for its wide band gap of 3.2-3.8 eV, excellent chemical stability, non-toxicity, and high visible light transmittance. NiO / Ga2O3 heterojunction solar-blind UV detectors have excellent properties, including structural stability, solar-blind UV sensitivity, low dark current, and high transmittance to visible light.

[0049] The main methods for preparing Ga2O3 thin films are: magnetron sputtering, metal organic chemical vapor deposition, pulsed laser deposition, molecular beam epitaxy, etc. The main methods for preparing NiO thin films are: magnetron sputtering, solution-gel method, molecular beam epitaxy, pulsed laser deposition and thermal spray method, etc. Compared with various preparation methods, magnetron sputtering technology is simple to operate and can achieve large-area coating. The prepared material has strong adhesion and a relatively uniform structure.

[0050] Most of the UV detectors in the prior art are prepared on a hard substrate. The present invention adopts a nickel oxide / gallium oxide PN junction type day-blind UV detector prepared by magnetron sputtering on a flexible substrate. The UV detector based on the nickel oxide / gallium oxide heterojunction prepared by the present invention has the characteristic of self-powered. The combination of the self-powered characteristic brought by the nickel oxide / gallium oxide heterojunction and the flexibility of the flexible substrate makes the present invention applicable to the field of wearable devices, and can further be used for direct UV light warning caused by the ozone hole. The nickel oxide / gallium oxide PN junction type day-blind UV detector prepared by the present invention also has a fully transparent characteristic. The fully transparent day-blind UV detector can minimize the absorption and reflection losses of light in the device, allowing more ultraviolet light to enter the detection area, thereby improving the photoelectric conversion efficiency of the detector, and then improving the sensitivity. In addition, the fully transparent day-blind UV detector of the present invention broadens its further application in flexible UV detectors or wearable devices.

[0051] In the present invention, each electrode layer is grown by step-shaped sputtering, and this design can effectively prevent the short circuit between layers during the magnetron sputtering process. In view of the low conductivity of NiO and Ga2O3, the present invention first covers the substrate with a bottom electrode layer during the preparation process to increase the carrier collection efficiency. The second layer of NiO mask deliberately leaves a small space for overlapping probes during subsequent electrical performance testing. The third layer of Ga2O3 is designed to be smaller in order to prevent contact with the bottom electrode. The fourth upper electrode layer is composed of two blocks, forming a typical pn junction electrode, ensuring that the two blocks fall accurately on the Ga2O3 layer, thereby optimizing the electrical performance and stability of the device. Through this fine structural design, the present invention not only improves the carrier collection efficiency, but also ensures good isolation between electrodes, avoids short circuits, and improves the performance and reliability of the entire device.

[0052] Compared with the general PN heterojunction solar-blind ultraviolet detector, the solar-blind ultraviolet detector prepared in the present invention is prepared on a flexible substrate, and the obtained performance is comparable to that of the solar-blind ultraviolet detector prepared on a hard substrate, while having the characteristics of flexibility and full transparency.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The present invention grows a nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector based on a flexible substrate. The prepared solar-blind ultraviolet detector has the characteristics of full transparency, self-powered, and flexible. The device is easy to carry and wearable.

[0055] (2) The present invention uses a transparent bottom electrode and a suitable mask to grow a step-shaped solar-blind ultraviolet detector, which can increase the carrier collection efficiency of the nickel oxide and gallium oxide films and improve the electrical performance of the device.

[0056] (3) The present invention combines Ga2O3 with NiO to develop a solar-blind ultraviolet detector based on a pn junction, which has a self-powered characteristic.

[0057] (4) The present invention grows a solar-blind ultraviolet detector on a flexible substrate, and the device prepared still has good working characteristics and full transparency in a bent state.

[0058] (5) The present invention grows a nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector on a flexible substrate by magnetron sputtering. Compared with other growth processes, the operation is simpler, the cost is lower, large-area preparation is possible, and batch growth feasibility is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic structural diagram of the magnetron sputtering preparation device of the present invention;

[0060] Figure 2 The schematic diagram of the detector preparation process and device structure of the present invention;

[0061] Figure 3 This is a physical picture of the device prepared in Example 1 of the present invention;

[0062] Figure 4 This is an IV test diagram of the device prepared in Example 1 of the present invention;

[0063] Figure 5 This is an IT test diagram of the device prepared in Example 1 of the present invention;

[0064] Figure 6 This is an IV test diagram of the device prepared in Example 2 of the present invention;

[0065] Figure 7 This is an IT test diagram of the device prepared in the second embodiment of the present invention. DETAILED DESCRIPTION

[0066] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0067] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0068] Embodiment 1:

[0069] In this embodiment, a fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector is prepared on a flexible substrate. The structure of the magnetron sputtering preparation device is as follows: Figure 1 The detector preparation process and device structure are shown in Figure 2 As shown, the specific steps include:

[0070] (1) Substrate processing:

[0071] Select a PET flexible substrate and cut it into 19.5mm×19.5mm in size and 0.25mm in thickness. Ultrasonicate the substrate in methanol, ethanol and deionized water for 5 minutes respectively, blow dry with high-purity nitrogen to obtain a clean and dry substrate. Send the cleaned substrate into the magnetron sputtering pretreatment chamber, and after the sputtering chamber is evacuated, introduce argon with a flow rate of 24.5sccm and oxygen with a flow rate of 10.5sccm. Set the sputtering power to 50W, and after sputtering for 2 minutes, obtain a substrate with stronger adhesion to the film.

[0072] (2) Preparation of bottom electrode layer:

[0073] The treated substrate is placed in a magnetron sputtering chamber, the target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), and the substrate obtained in step (1) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is introduced; the sputtering pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and after the sputtering is completed, a BGZO film with a thickness of 200 nm is obtained;

[0074] (3) Preparation of NiO thin film:

[0075] The target material is a high-purity NiO ceramic target material with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (15.5mm*12.5mm) is selected to cover the BGZO film surface, and the BGZO film sample obtained in the step (2) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 100W respectively, and after pre-sputtering for 10min, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a nickel oxide film with a thickness of 350nm is obtained;

[0076] (4) Preparation of Ga2O3 thin film:

[0077] The target material is a high-purity Ga2O3 ceramic target with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (12.5mm*9.5mm) is selected to cover the nickel oxide film surface, and the nickel oxide film sample obtained in step (3) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 100W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a gallium oxide film with a thickness of 150nm is obtained;

[0078] (5) Preparation of upper electrode layer:

[0079] The treated substrate is placed in a magnetron sputtering chamber, a target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), a stainless steel mask plate with two square openings (4 mm*4 mm) is selected to cover the surface of the gallium oxide film, and the gallium oxide film substrate obtained in the step (4) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is introduced; the sputtering gas pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and a BGZO film with a thickness of 100 nm is obtained after the sputtering is completed.

[0080] In this embodiment, a fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector is prepared on a flexible substrate. Figure 3 The device shown is transparent and has bendable properties. Figure 4 This is the IV test diagram of the device prepared in Example 1 of the present invention under dark current, 254nm ultraviolet light and 365nm ultraviolet light. The prepared solar-blind ultraviolet detector is a typical PN junction detector, that is, it is forward-conducting and reverse-cutoff. The device has a good response to 254nm ultraviolet light and has the ability to resolve solar-blind ultraviolet light of different bands. Figure 5 This is an IT test diagram of the device prepared in Example 1 of the present invention. The figure is a single IT curve diagram of the device under 0V and 254nm ultraviolet light. The rise time and fall time are 0.64 seconds and 0.45 seconds respectively, indicating that the device can be self-powered without an external voltage and has a faster response time and response speed.

[0081] Embodiment 2:

[0082] This embodiment is basically the same as the first embodiment, except that the preparation powers of NiO and Ga2O3 thin film layers are different:

[0083] In this embodiment, a fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector prepared on a flexible substrate includes the following steps:

[0084] (1) Substrate processing:

[0085] Select a PET flexible substrate and cut it into 19.5mm×19.5mm in size and 0.25mm in thickness. Ultrasonicate the substrate in methanol, ethanol and deionized water for 5 minutes respectively, blow dry with high-purity nitrogen to obtain a clean and dry substrate. Send the cleaned substrate into the magnetron sputtering pretreatment chamber, and after the sputtering chamber is evacuated, introduce argon with a flow rate of 24.5sccm and oxygen with a flow rate of 10.5sccm. Set the sputtering power to 50W, and after sputtering for 2 minutes, obtain a substrate with stronger adhesion to the film.

[0086] (2) Preparation of bottom electrode layer:

[0087] The treated substrate is placed in a magnetron sputtering chamber, the target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), and the substrate obtained in step (1) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is introduced; the sputtering pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and after the sputtering is completed, a BGZO film with a thickness of 200 nm is obtained;

[0088] (3) Preparation of NiO thin film:

[0089] The target material is a high-purity NiO ceramic target material with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (15.5mm*12.5mm) is selected to cover the BGZO film surface, and the BGZO film sample obtained in step (2) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 150W respectively, and after pre-sputtering for 10min, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a nickel oxide film with a thickness of 350nm is obtained;

[0090] (4) Preparation of Ga2O3 thin film:

[0091] The target material is a high-purity Ga2O3 ceramic target with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (12.5mm*9.5mm) is selected to cover the nickel oxide film surface, and the nickel oxide film sample obtained in step (3) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 150W respectively, and after pre-sputtering for 10min, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a gallium oxide film with a thickness of 150nm is obtained;

[0092] (5) Preparation of upper electrode layer:

[0093] The treated substrate is placed in a magnetron sputtering chamber, a target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), a stainless steel mask plate with two square openings (4 mm*4 mm) is selected to cover the surface of the gallium oxide film, and the gallium oxide film substrate obtained in the step (4) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is introduced; the sputtering gas pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and a BGZO film with a thickness of 100 nm is obtained after the sputtering is completed.

[0094] Figure 6 This is the IV test diagram of the device prepared in Example 2 of the present invention under dark current, 254nm ultraviolet light and 365nm ultraviolet light. The prepared solar-blind ultraviolet detector is a typical PN junction detector, that is, it is forward-conducting and reverse-cutoff. The device has a good response to 254nm ultraviolet light and has the ability to resolve solar-blind ultraviolet light of different bands. Figure 7This is an IT test diagram of the device prepared in Example 2 of the present invention. The figure is a single IT curve diagram of the device under 0V and 254nm ultraviolet light. The rise time and fall time are 0.95 seconds and 0.36 seconds respectively, indicating that the device can be self-powered without an external voltage and has a faster response time and response speed.

[0095] Embodiment three:

[0096] This embodiment is basically the same as the first embodiment, except that the thickness of the NiO and Ga2O3 thin film layers are different:

[0097] In this embodiment, a fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector prepared on a flexible substrate includes the following steps:

[0098] (1) Substrate processing:

[0099] Select a PET flexible substrate and cut it into 19.5mm×19.5mm in size and 0.25mm in thickness. Ultrasonicate the substrate in methanol, ethanol and deionized water for 5 minutes respectively, blow dry with high-purity nitrogen to obtain a clean and dry substrate. Send the cleaned substrate into the magnetron sputtering pretreatment chamber, and after the sputtering chamber is evacuated, introduce argon with a flow rate of 24.5sccm and oxygen with a flow rate of 10.5sccm. Set the sputtering power to 50W, and after sputtering for 2 minutes, obtain a substrate with stronger adhesion to the film.

[0100] (2) Preparation of bottom electrode layer:

[0101] The treated substrate is placed in a magnetron sputtering chamber, the target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), and the substrate obtained in step (1) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is introduced; the sputtering pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and after the sputtering is completed, a BGZO film with a thickness of 200 nm is obtained;

[0102] (3) Preparation of NiO thin film:

[0103] The target material is a high-purity NiO ceramic target material with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (15.5mm*12.5mm) is selected to cover the BGZO film surface, and the BGZO film sample obtained in the step (2) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 100W respectively, and after pre-sputtering for 10min, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a nickel oxide film with a thickness of 400nm is obtained;

[0104] (4) Preparation of Ga2O3 thin film:

[0105] The target material is a high-purity Ga2O3 ceramic target material with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (12.5mm*9.5mm) is selected to cover the nickel oxide film surface, and the nickel oxide film sample obtained in step (3) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 100W respectively, and after pre-sputtering for 10min, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a gallium oxide film with a thickness of 200nm is obtained;

[0106] (5) Preparation of upper electrode layer:

[0107] The treated substrate is placed in a magnetron sputtering chamber, a target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), a stainless steel mask plate with two square openings (4 mm*4 mm) is selected to cover the surface of the gallium oxide film, and the gallium oxide film substrate obtained in the step (4) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is introduced; the sputtering gas pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and a BGZO film with a thickness of 100 nm is obtained after the sputtering is completed.

[0108] Embodiment 4:

[0109] This embodiment is basically the same as the first embodiment, except that the sizes of the stainless steel mask plates used in the preparation of NiO, Ga2O3 and the upper electrode are different:

[0110] In this embodiment, a fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector prepared on a flexible substrate includes the following steps:

[0111] (1) Substrate processing:

[0112] Select a PET flexible substrate and cut it into 19.5mm×19.5mm in size and 0.25mm in thickness. Ultrasonicate the substrate in methanol, ethanol and deionized water for 5 minutes respectively, blow dry with high-purity nitrogen to obtain a clean and dry substrate. Send the cleaned substrate into the magnetron sputtering pretreatment chamber, and after the sputtering chamber is evacuated, introduce argon with a flow rate of 24.5sccm and oxygen with a flow rate of 10.5sccm. Set the sputtering power to 50W, and after sputtering for 2 minutes, obtain a substrate with stronger adhesion to the film.

[0113] (2) Preparation of bottom electrode layer:

[0114] The treated substrate is placed in a magnetron sputtering chamber, the target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), and the substrate obtained in step (1) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is introduced; the sputtering pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and after the sputtering is completed, a BGZO film with a thickness of 200 nm is obtained;

[0115] (3) Preparation of NiO thin film:

[0116] The target material is a high-purity NiO ceramic target material with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (17.5mm*14.5mm) is selected to cover the BGZO film surface, and the BGZO film sample obtained in the step (2) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 100W respectively, and after pre-sputtering for 10min, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a nickel oxide film with a thickness of 350nm is obtained;

[0117] (4) Preparation of Ga2O3 thin film:

[0118] The target material is a high-purity Ga2O3 ceramic target material with a purity of 99.99%; a stainless steel mask plate with a rectangular opening (14.5mm*11.5mm) is selected to cover the nickel oxide film surface, and the nickel oxide film sample obtained in step (3) is placed on the sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 15sccm is introduced; the sputtering pressure and sputtering power are set to 0.5Pa and 100W respectively, and after pre-sputtering for 10min, the baffle is opened to start formal sputtering, and after waiting for the sputtering to be completed, a gallium oxide film with a thickness of 150nm is obtained;

[0119] (5) Preparation of upper electrode layer:

[0120] The treated substrate is placed in a magnetron sputtering chamber, a target material is a ZnO ceramic target material co-doped with boron (0.2 wt%) and gallium (1.8 wt%), a stainless steel mask plate with two square openings (6 mm*6 mm) is selected to cover the surface of the gallium oxide film, and the gallium oxide film substrate obtained in the step (4) is placed on a sample table; after the sputtering chamber is evacuated, argon gas with a flow rate of 25 sccm is passed / into; the sputtering gas pressure and sputtering power are set to 0.4 Pa and 150 W respectively, and after pre-sputtering for 10 minutes, the baffle is opened to start formal sputtering, and a BGZO film with a thickness of 100 nm is obtained after the sputtering is completed.

[0121] In summary, the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector prepared by the present invention has the characteristics of full transparency, self-powered and flexible, which broadens the application prospects of future flexible ultraviolet detectors or wearable devices.

[0122] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector, characterized in that: From bottom to top, it includes a flexible substrate, a bottom electrode layer, a NiO thin film layer, a Ga2O3 thin film layer, and an upper electrode layer.

2. The fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to claim 1, characterized in that: The flexible substrate comprises a PET flexible substrate, the bottom electrode layer and the top electrode layer are both BGZO electrode layers, and the bottom electrode layer, the NiO thin film layer, the Ga2O3 thin film layer and the top electrode layer are arranged in a stepped manner.

3. The fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to claim 1, characterized in that: The thickness of the flexible substrate is 0.1-0.5 mm, the thickness of the bottom electrode layer is 100-200 nm, the thickness of the NiO thin film layer is 100-500 nm, the thickness of the Ga2O3 thin film layer is 100-150 nm, and the thickness of the top electrode layer is 100-200 nm.

4. A method for preparing a fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1, pre-treating the flexible substrate to obtain a pre-treated flexible substrate; S2, sputtering a bottom electrode layer on the pretreated flexible substrate by magnetron sputtering; S3, sputtering a NiO thin film layer on the bottom electrode layer by using a mask and magnetron sputtering; S4, sputtering a Ga2O3 thin film layer on the NiO thin film layer by using a mask and a magnetron sputtering method; S5. Sputtering an upper electrode layer on the Ga2O3 thin film layer by using a mask and a magnetron sputtering method to prepare the nickel oxide / gallium oxide PN junction type solar-blind ultraviolet detector.

5. The method for preparing the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to claim 4, characterized in that: In step S1, the pretreatment process specifically includes the following steps: selecting a flexible substrate and cutting it into a size of 17-22 mm*17-22 mm; ultrasonically treating the cut substrate in methanol, ethanol and deionized water for 5-30 min respectively, and drying it with nitrogen to obtain a clean and dry substrate; sending the cleaned substrate into a magnetron sputtering pretreatment chamber, and evacuating the chamber until the vacuum degree of the magnetron sputtering chamber is 2*10 -6 Torr, introduce argon gas with a flow rate of 10-30 sccm and oxygen gas with a flow rate of 5-15 sccm, set the sputtering power to 50-100 W, and obtain the pretreated substrate after sputtering for 1-5 minutes.

6. The method for preparing the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to claim 4, characterized in that: In step S2, the target material used for the magnetron sputtering is a ZnO ceramic target material co-doped with 1.2-2.4 wt% of boron and 0.1-0.3 wt% of gallium, and the vacuum degree of the magnetron sputtering chamber is 2*10 -6 Torr, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and the baffle is opened after pre-sputtering for 10 to 30 minutes to start formal sputtering, and the formal sputtering time is 15 to 30 minutes.

7. The method for preparing the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to claim 4, characterized in that: In step S3, the rectangular size of the mask is 13-18 mm*10-15 mm, the target material used for the magnetron sputtering is a NiO ceramic target material with a purity greater than 99.99%, and the background vacuum degree of the magnetron sputtering is 2*10 -6 Torr, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and the baffle is opened after pre-sputtering for 10 to 30 minutes to start formal sputtering, and the formal sputtering time is 110 to 150 minutes.

8. The method for preparing the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to claim 4, characterized in that: In step S4, the rectangular size of the mask is 10-15 mm*7-12 mm, the target material used for the magnetron sputtering is a Ga2O3 ceramic target material with a purity greater than 99.99%, and the vacuum degree of the magnetron sputtering chamber is 2*10 -6 Torr, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and the baffle is opened after pre-sputtering for 10 to 30 minutes to start formal sputtering, and the formal sputtering time is 60 to 100 minutes.

9. The method for preparing the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to claim 4, characterized in that: In step S5, there are 1 to 3 masks, the size of the masks is 3 to 5 mm*3 to 5 mm, the target material used for the magnetron sputtering is a ZnO ceramic target co-doped with 1.2 to 2.4 wt% of boron and 0.1 to 0.3 wt% of gallium, the vacuum degree of the magnetron sputtering chamber is 5 to 7 Pa, the magnetron sputtering is carried out in an argon atmosphere, the gas flow rate of the argon atmosphere is in the range of 10 to 30 sccm, the sputtering pressure is 0.1 to 0.5 Pa, the sputtering power is 100 to 250 W, and the baffle is opened after 10 to 30 minutes of pre-sputtering to start formal sputtering, and the formal sputtering time is 10 to 25 minutes.

10. Use of the fully transparent nickel oxide / gallium oxide PN junction solar-blind ultraviolet detector according to any one of claims 1 to 3 in the field of preparing wearable devices.

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