Self-driven ultraviolet photodetector based on Ga-doped ZnO microwires and its fabrication method

Abstract

This invention discloses a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires, comprising a conductive glass, an Au thin-film electrode, an MgO insulating layer, and an n-AgNWs@ZnO:Ga microwire disposed on the same side of the conductive glass. The n-AgNWs@ZnO:Ga microwire is disposed between the MgO insulating layer. An electron blocking layer is disposed on the side of the MgO insulating layer and the n-AgNWs@ZnO:Ga microwire away from the conductive glass. The electron blocking layer is connected to a p-GaN thin film. A thin-film electrode is disposed on the side of the p-GaN thin film facing the electron blocking layer, and a substrate is disposed on the side away from the electron blocking layer. This invention also discloses a method for fabricating this self-driven ultraviolet photodetector. The self-driven ultraviolet photodetector of this invention has fewer surface defects, better charge transport, no carrier recombination in the depletion region, low dark current, high metal-oxide interface migration, reduced reverse leakage current, and reduced photocurrent.

Description

Technical Field

[0001] This invention pertains to photodetectors and their fabrication methods, specifically a self-driven ultraviolet photodetector based on Ga-doped ZnO micrometer wires and its fabrication method. Background Technology

[0002] High-performance, self-driven, low-dimensional ultraviolet photodetectors have significant applications in remote sensing imaging, environmental monitoring, medical testing, and military equipment, and a range of detection and imaging products already exist. With the further miniaturization and integration of information devices, the field of high-performance, low-dimensional, self-driven detection holds great promise for future applications.

[0003] Zinc oxide (ZnO), as a direct bandgap, wide bandgap semiconductor material with a bandgap of 3.37 eV, is widely used in detectors. The excellent aspect ratio, flexibility, and crystallinity of zinc oxide microwires offer good performance in low-dimensional photodetectors. Therefore, in this invention, we use chemical vapor deposition (CVD) to grow zinc oxide microwires to fabricate a low-dimensional self-driven ultraviolet photodetector, which has significant application value in the detection field. However, obtaining highly stable p-type zinc oxide still presents many challenges. Therefore, p-GaN was introduced to fabricate zinc oxide-based ultraviolet photodetectors, but problems such as low electron mobility, slow response speed, severe carrier recombination, and large reverse leakage current still exist. Research has found that introducing a magnesium oxide interlayer can modulate the interface, promoting effective carrier separation and significantly reducing the reverse leakage current. The introduction of the magnesium oxide interlayer leads to an increase in device resistance, reducing both the reverse leakage current and photocurrent.

[0004] Chinese patent CN115084296A discloses an ultraviolet detector as a homojunction detector. Due to the intrinsic defects of ZnO, zinc oxide, as an intrinsic n-type semiconductor, is difficult to prepare as p-type zinc oxide due to the compensation effect of intrinsic n-type carriers and the limitations of asymmetric doping. Furthermore, due to oxygen adsorption and desorption on the ZnO surface, the response speed of pure ZnO photodetectors is generally slow. Chinese patent CN116013941A discloses a micrometer-line photodetector array, but ZnO:Ga MW / GaN devices suffer from some inherent problems at the interface between heterojunction materials.

[0005] In summary, existing ZnO:Ga MW / GaN self-driven ultraviolet photodetectors suffer from problems such as surface defect states, poor charge transport, severe carrier recombination in the depletion region, large dark current, and low metal-oxide interface mobility. Summary of the Invention

[0006] Purpose of the invention: In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires with high EQE, fast response speed and good electrical properties. Another purpose of this invention is to provide a method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires that effectively improves carrier transport, enhances electron mobility, greatly increases photocurrent and improves response time.

[0007] Technical Solution: The present invention discloses a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires, comprising a conductive glass, an Au thin-film electrode, an MgO insulating layer, and an n-AgNWs@ZnO:Ga microwire disposed on the same side of the conductive glass, the n-AgNWs@ZnO:Ga microwire disposed between the MgO insulating layer, an electron blocking layer disposed on the side of the MgO insulating layer and the n-AgNWs@ZnO:Ga microwire away from the conductive glass, the electron blocking layer being connected to a p-GaN thin film, a thin-film electrode disposed on the side of the p-GaN thin film facing the electron blocking layer, and a substrate disposed on the side away from the electron blocking layer.

[0008] Furthermore, the Au thin-film electrode has a thickness of 40–50 nm, the MgO insulating layer has a thickness of 1–3 μm, the electron blocking layer has a thickness of 10–20 nm, and the thin-film electrode has a thickness of 50–100 nm. A MgO insulating layer thickness greater than 3 μm leads to excessive film thickness, making it prone to detachment, reducing insulation capacity, weakening electron blocking ability, and affecting conductivity, while initially providing some insulation. An electron blocking layer thickness less than 10 nm has limited electron blocking effect. The Au thin-film electrode is used to collect electrons, while the MgO electron blocking layer is used to prevent electron movement from the n-type material ZnO to GaN.

[0009] Furthermore, the ZnO:Ga microwires in n-AgNWs@ZnO:Ga microwires have a length of 1–3 cm, a side length of 10–20 μm, and a quadrilateral cross-section, which provides a larger contact area between the microwires and the substrate compared to a circle.

[0010] Furthermore, the thickness of the p-GaN film is 300–350 μm, and the hole concentration is 10. 18 ~10 19 / cm 3 Hole mobility is 20–150 cm. 2 / V·s.

[0011] Furthermore, the electron blocking layer is a MgO electron blocking layer, the thin-film electrode is a Ni / Au composite thin-film electrode, and the substrate is a sapphire substrate. The presence of dark current leads to energy waste, shortened device lifetime, increased error, and leakage current risk. Using a MgO electron blocking layer reduces dark current, and silver nanowires increase electron mobility, which enhances the response time of the photodetector. Fast response time is an important performance characteristic of the detector.

[0012] The present invention discloses a method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires, comprising the following steps:

[0013] Step 1: Deposit an Au thin film electrode at one end of the conductive surface of the conductive glass;

[0014] Step 2: Deposit a thin film electrode at one end of the p-GaN thin film surface;

[0015] Step 3: Use a mask to block the thin film electrode and deposit an electron blocking layer at the other end of the p-GaN thin film.

[0016] Step 4: Use a mask to cover the area on the surface of the thin film electrode and the p-GaN thin film that will be used for subsequent placement of n-AgNWs@ZnO:Ga microwires, and deposit an MgO insulating layer on the surface of the MgO electron blocking layer.

[0017] Step 5: Uniformly spin-coat AgNWs onto the surface of Ga-doped ZnO microwires to obtain n-AgNWs@ZnO:Ga microwires;

[0018] Step six: Place the n-AgNWs@ZnO:Ga microwire at the location blocked in step four;

[0019] Step 7: Cover the surface of the n-AgNWs@ZnO:Ga microwire with the conductive glass obtained in Step 1.

[0020] Furthermore, in step one, the conductive glass is placed in acetone, ethanol and deionized water in sequence before vapor deposition, ultrasonically cleaned, and then the surface moisture is blown off with nitrogen.

[0021] Furthermore, in step two, the p-GaN thin film is grown on the substrate using molecular beam epitaxy (MBE) with a hole concentration of 10. 18 ~10 19 / cm 3 Hole mobility is 20–150 cm. 2 The film was placed in acetone, ethanol and deionized water in sequence, ultrasonically cleaned, and then the surface moisture was blown off with nitrogen. Ni and Au were then deposited sequentially on one end of the p-GaN film to obtain the thin film electrode.

[0022] Further, in step five, the preparation method of Ga-doped ZnO microwires is as follows: ZnO powder, gallium oxide powder, and carbon powder are ground and mixed in a mass ratio of 9:1:10, placed in a high-temperature tube furnace, and heated. The gas flow rate is set to 110-120 sccm, and the temperature is increased at a rate of 15-20 degrees Celsius per minute to 1100-1150 degrees Celsius for 30-40 minutes. Then, the oxygen valve connected to the high-temperature tube furnace is opened, the gas flow rate is set to 15-20 sccm, and heating is continued for 20-30 minutes. The Ga-doped ZnO microwires are fixed to a glass slide by indium particles, and Ag nanowires are uniformly spin-coated onto the surface of the Ga-doped ZnO microwires. The electron concentration of n-AgNWs@ZnO:Ga microwires is 10. 17 ~10 19 / cm 3 Electron mobility is 5–150 cm⁻¹ 2 / V·s. The higher the electron concentration and electron mobility, the better, as higher concentrations result in faster detector response. However, due to the inherent properties of the material, achieving even higher concentrations becomes difficult.

[0023] Fabrication Principle: The MgO electron blocking layer acts as an electron barrier. Under the influence of an electric field, photogenerated holes can enter the conduction band of MgO, while photogenerated electrons cannot enter the valence band of p-type GaN. The high barrier generated by MgO prevents electron backflow and suppresses the recombination process. Electrons are then quickly and efficiently separated by the built-in electric field and subsequently collected by electrodes via ZnO. Simultaneously, the introduction of the MgO layer helps reduce interface defects that may be caused by cracks and pinholes. By minimizing the surface states of the n-ZnO MW interface, these defects are reduced, significantly lowering the dark current of the device and improving the detection capability of small signals. Therefore, the photocurrent increases, and the dark current is effectively minimized. The presence of AgNWs enhances carrier transport, thereby increasing the electron mobility within the device. This, in turn, greatly improves the response speed of the photodetector. Furthermore, the high transparency of the AgNWs lattice allows sufficient light to penetrate and illuminate the n-ZnO:Ga-MW region. This ensures that sufficient light reaches the active region of the device. Therefore, the introduction of AgNWs enhances the overall performance of the photodetector by improving charge carrier transport, increasing electron mobility, and achieving efficient light transmission. Introducing AgNWs enhances the absorption of ultraviolet light by zinc oxide microwires, further improving the electrical properties of a single zinc oxide microwire, and also mitigates the increased resistance caused by the introduction of MgO. Through the synergistic effect of interface modulation of the MgO electron blocking layer and the surface plasmon resonance effect of AgNWs, the electrical characteristics of the device are improved, and the response speed is increased, resulting in a low-dimensional self-driven ultraviolet photodetector with high EQE.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0025] 1. Self-driven ultraviolet photodetectors have fewer surface defects, better charge transport, no recombination of charge carriers in the depletion region, small dark current, and high metal-oxide interface migration.

[0026] 2. Introducing a magnesium oxide interlayer helps to increase device resistance, reduce reverse leakage current, and reduce photocurrent;

[0027] 3. By introducing silver nanowires to modify zinc oxide microwires, the plasmon effect can be utilized to effectively improve carrier transport, enhance electron mobility, greatly increase photocurrent, and improve response time.

[0028] 4. The MgO electron blocking layer can reduce dark current, and silver nanowires are beneficial to increasing electron mobility and electron concentration, thereby enhancing the photocurrent and response time of the photodetector. Fast response time is an important performance characteristic of the detector. Attached Figure Description

[0029] Figure 1 This is a scanning electron microscope image of a single quadrilateral ZnO:Ga micron-sized wire of the present invention.

[0030] Figure 2 This is a schematic diagram of the structure of the present invention.

[0031] Figure 3 These are the IV comparison curves of the self-driven ultraviolet photodetector of this invention under dark field and 370nm illumination.

[0032] Figure 4 This is the on / off current curve of the self-driven ultraviolet photodetector of the present invention.

[0033] Figure 5 This is the response rate curve of the self-driven ultraviolet photodetector of the present invention under 370nm pulsed laser.

[0034] Figure 6 The EQE curve of the self-driven ultraviolet photodetector of the present invention under light irradiation at wavelengths from 300nm to 450nm is shown. Detailed Implementation

[0035] In the following embodiments, the ITO conductive glass has dimensions of 30mm × 15mm × 1mm, and the resistance of the conductive surface of the ITO conductive glass 1 is 3 to 5 ohms.

[0036] Example 1

[0037] A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires includes the following steps:

[0038] Step 1: Fabrication of gallium-doped zinc oxide microwires (ZnO:Ga MW):

[0039] (1) Use an electronic balance to weigh a specific weight of high-purity ZnO powder, gallium oxide powder and carbon powder, and grind and mix them in a mass ratio of 9:1:10. After the mixture is fully ground, put it into a bottle for later use.

[0040] (2) Take 6 grams of mixed powder into a corundum boat and place it into the heating zone of a dual-temperature zone high-temperature tube furnace;

[0041] (3) Open the argon (Ar) valve connected to the high-temperature tubular furnace, set the gas flow rate to 120 sccm, and then start the high-temperature tubular furnace heating program to raise the temperature to 1100 degrees Celsius at a rate of 20 degrees Celsius per minute.

[0042] (4) After the temperature rises to 1100 degrees Celsius and the reactants are heated stably for 30 minutes, the oxygen (O2) valve connected to the high-temperature tube furnace is opened, the gas flow rate is set to 15 sccm and the heating continues for 30 minutes.

[0043] (5) After the reaction time is complete, turn off the high-temperature tube furnace and allow it to cool naturally to room temperature. Remove the corundum boat, and observe the growth of the microwires within it. Figure 1 The optical photographs shown are for reference. (By...) Figure 1 It can be seen that the cross-section of the ZnO:Ga microwire is quadrilateral, with a side length of 15μm and a length of 2cm.

[0044] Step 2: Construct Au thin film electrode 2 on the conductive surface of ITO conductive glass 1:

[0045] (1) Place ITO conductive glass 1 in acetone, ethanol and deionized water in sequence, clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0046] (2) An Au thin film electrode 2 with a width of 5 mm and a thickness of 50 nm was deposited on one end of the conductive surface of the ITO conductive glass 1 using an electron beam evaporation apparatus, while maintaining a vacuum level of 6.7 × 10⁻⁶ in the electron beam evaporation apparatus. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at For backup.

[0047] Step 3: Construct thin film electrode 6 on the surface of p-GaN thin film 7:

[0048] (1) The p-GaN thin film 7 was grown on the sapphire substrate 8 using the MBE method, with a hole concentration of 10. 18 / cm 3 Hole mobility is 80cm 2 / V·s, with a thickness of 330μm.

[0049] (2) Take a 5mm×10mm (length×width) p-GaN film 7 and place it in acetone, ethanol and deionized water in sequence. Clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0050] (3) Using an electron beam evaporator, Ni and Au thin film electrodes with a thickness of 50 nm were sequentially deposited at one end of the p-GaN thin film 7, while maintaining a vacuum degree of 6.7 × 10⁻⁶. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at A thin film electrode 6 with a thickness of 100 nm was obtained for later use.

[0051] Step 4: Deposit an MgO electron blocking layer 4 on the surface of the p-GaN thin film 7: The thin film electrode 6 is blocked with a mask, and a 15 nm thick MgO electron blocking layer 4 is deposited on the surface of the p-GaN thin film 7 using an electron beam evaporator, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0052] Step 5: Deposit an MgO insulating layer 3 on the surface of the MgO electron blocking layer 4: Use a mask to cover the portion of the thin film electrode 6 and the p-GaN thin film 7 surface where the n-AgNWs@ZnO:Ga microwire 5 will be placed, with a width of approximately 30 μm. Use an electron beam evaporator to deposit a 2 μm thick MgO insulating layer 3 on the surface of the p-GaN thin film 7, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0053] Step 6: Spin-coating Ag nanowires onto the surface of ZnO:Ga microwires: Select a smooth ZnO:Ga microwire, fix the ZnO:Ga microwire to the glass slide surface using indium (In) particles, and uniformly spin-coat Ag nanowires onto the surface of the ZnO:Ga microwire using a spin-coating method to obtain n-AgNWs@ZnO:Ga microwire 5, for later use. The electron concentration of the n-AgNWs@ZnO:Ga microwire is 10. 18 / cm 3 Electron mobility is 80 cm⁻¹ 2 / V·s.

[0054] Step 7: Use tweezers to place the n-AgNWs@ZnO:Ga microwire 5 in the position blocked in step 5, ensuring that the n-AgNWs@ZnO:Ga microwire 5 is in close contact with the MgO electron blocking layer 4;

[0055] Step 8: Cover the conductive surface of the ITO conductive glass 1 with Au thin film electrode 2 obtained in step 2 onto the surface of the n-AgNWs@ZnO:Ga microwire 5, and clamp the entire device with two metal clips.

[0056] like Figure 2 The self-driven ultraviolet photodetector based on Ga-doped ZnO microwires obtained in this embodiment comprises, from bottom to top, a sapphire substrate 8, a p-GaN thin film 7, a Ni / Au thin film electrode 6 on the left side of the p-GaN thin film 7, and an MgO electron blocking layer 4 on the middle right side of the surface. The MgO electron blocking layer 4 has an n-AgNWs@ZnO:Ga microwire 5 and an MgO insulating layer 3 on its surface, with the n-AgNWs@ZnO:Ga microwire 5 positioned between the MgO insulating layer 3. The top of both is an ITO conductive glass 1. An Au thin film electrode 2 is also present on the lower surface of the ITO conductive glass 1 facing the MgO electron blocking layer 4.

[0057] like Figure 3 The image shows the IV curves of the device measured under 370nm light and in darkness. It can be seen that the current has increased significantly, indicating that the device has a significant response to ultraviolet light.

[0058] like Figure 4 The image shows the It curves of the device measured under 370nm light and in darkness, demonstrating that the device not only has a significant response to ultraviolet light but also exhibits periodic stability.

[0059] like Figure 5 The single-cycle transient time-resolved response of the device under self-driven illumination with a 370 nm pulsed laser is shown. The response time is determined by the duration between 10% and 90% of the maximum photocurrent, accurately capturing the decay process. The photoresponse switching curves demonstrate that the photodetector can precisely distinguish and respond to each pulse signal. It can be seen that the device achieves a significantly enhanced rise / fall time of 3.64 μs / 252 μs.

[0060] like Figure 6 The results show the external quantum efficiency (EQE) under different wavelengths of light, with the highest EQE reaching 92.37% at 370 nm, indicating that the device has high photoelectric conversion efficiency, high sensitivity and low loss.

[0061] Example 2

[0062] A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires includes the following steps:

[0063] Step 1: Fabrication of gallium-doped zinc oxide microwires (ZnO:Ga MW):

[0064] (1) Use an electronic balance to weigh a specific weight of high-purity ZnO powder, gallium oxide powder and carbon powder, and grind and mix them in a mass ratio of 9:1:10. After the mixture is fully ground, put it into a bottle for later use.

[0065] (2) Take 6 grams of mixed powder into a corundum boat and place it into the heating zone of a dual-temperature zone high-temperature tube furnace;

[0066] (3) Open the argon (Ar) valve connected to the high-temperature tubular furnace, set the gas flow rate to 110 sccm, and then start the high-temperature tubular furnace heating program to raise the temperature to 1150 degrees Celsius at a rate of 15 degrees Celsius per minute.

[0067] (4) After the temperature rises to 1150 degrees Celsius and the reactants are heated stably for 40 minutes, the oxygen (O2) valve connected to the high-temperature tube furnace is opened, the gas flow rate is set to 20 sccm and the heating continues for 20 minutes.

[0068] (5) When the reaction time is over, turn off the high-temperature tube furnace and let it cool to room temperature naturally. Take out the corundum boat and obtain a ZnO:Ga microwire with a quadrilateral cross-section, a side length of 10 μm and a length of 1 cm, for later use.

[0069] Step 2: Construct Au thin film electrode 2 on the conductive surface of ITO conductive glass 1:

[0070] (1) Place ITO conductive glass 1 in acetone, ethanol and deionized water in sequence, clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0071] (2) An Au thin film electrode 2 with a width of 5 mm and a thickness of 40 nm was deposited on one end of the conductive surface of the ITO conductive glass 1 using an electron beam evaporation apparatus, while maintaining a vacuum level of 6.7 × 10⁻⁶ in the electron beam evaporation apparatus. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at For backup.

[0072] Step 3: Construct thin film electrode 6 on the surface of p-GaN thin film 7:

[0073] (1) The p-GaN thin film 7 was grown on the sapphire substrate 8 using the MBE method, with a hole concentration of 10. 19 / cm 3 Hole mobility is 20cm 2 / V·s, with a thickness of 300μm.

[0074] (2) Take a 5mm×10mm (length×width) p-GaN film 7 and place it in acetone, ethanol and deionized water in sequence. Clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0075] (3) Using an electron beam evaporation apparatus, Ni and Au thin film electrodes with a thickness of 25 nm were sequentially deposited at one end of the p-GaN thin film 7, while maintaining a vacuum degree of 6.7 × 10⁻⁶. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at A thin film electrode 6 with a thickness of 50 nm was obtained for later use.

[0076] Step 4: Deposit a MgO electron blocking layer 4 on the surface of the p-GaN thin film 7: The thin film electrode 6 is blocked with a mask, and a 10 nm thick MgO electron blocking layer 4 is deposited on the surface of the p-GaN thin film 7 using an electron beam evaporator, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0077] Step 5: Deposit an MgO insulating layer 3 on the surface of the MgO electron blocking layer 4: Use a mask to cover the portion of the thin film electrode 6 and the p-GaN thin film 7 surface where the n-AgNWs@ZnO:Ga microwire 5 will be placed, with a width of approximately 30 μm. Use an electron beam evaporator to deposit a 1 μm thick MgO insulating layer 3 on the surface of the p-GaN thin film 7, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0078] Step 6: Spin-coating Ag nanowires onto the surface of ZnO:Ga microwires: Select a smooth ZnO:Ga microwire, fix the ZnO:Ga microwire to the glass slide surface using indium (In) particles, and uniformly spin-coat Ag nanowires onto the surface of the ZnO:Ga microwire using a spin-coating method to obtain n-AgNWs@ZnO:Ga microwire 5, for later use. The electron concentration of the n-AgNWs@ZnO:Ga microwire is 10. 19 / cm 3 Electron mobility is 5 cm⁻¹ 2 / V·s.

[0079] Step 7: Use tweezers to place the n-AgNWs@ZnO:Ga microwire 5 in the position blocked in step 5, ensuring that the n-AgNWs@ZnO:Ga microwire 5 is in close contact with the MgO electron blocking layer 4;

[0080] Step 8: Cover the conductive surface of the ITO conductive glass 1 with Au thin film electrode 2 obtained in step 2 onto the surface of the n-AgNWs@ZnO:Ga microwire 5, and clamp the entire device with two metal clips.

[0081] Example 3

[0082] A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires includes the following steps:

[0083] Step 1: Fabrication of gallium-doped zinc oxide microwires (ZnO:Ga MW):

[0084] (1) Use an electronic balance to weigh a specific weight of high-purity ZnO powder, gallium oxide powder and carbon powder, and grind and mix them in a mass ratio of 9:1:10. After the mixture is fully ground, put it into a bottle for later use.

[0085] (2) Take 6 grams of mixed powder into a corundum boat and place it into the heating zone of a dual-temperature zone high-temperature tube furnace;

[0086] (3) Open the argon (Ar) valve connected to the high-temperature tube furnace, set the gas flow rate to 115 sccm, and then start the high-temperature tube furnace heating program to raise the temperature to 1125 degrees Celsius at a rate of 16 degrees Celsius per minute.

[0087] (4) After the temperature rises to 1125 degrees Celsius and the reactants are heated stably for 35 minutes, the oxygen (O2) valve connected to the high-temperature tube furnace is opened, the gas flow rate is set to 17 sccm and the heating continues for 25 minutes.

[0088] (5) When the reaction time is over, turn off the high-temperature tube furnace and let it cool to room temperature naturally. Take out the corundum boat and obtain ZnO:Ga microwires with a quadrilateral cross-section, a side length of 20μm and a length of 3cm, for later use.

[0089] Step 2: Construct Au thin film electrode 2 on the conductive surface of ITO conductive glass 1:

[0090] (1) Place ITO conductive glass 1 in acetone, ethanol and deionized water in sequence, clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0091] (2) An Au thin film electrode 2 with a width of 5 mm and a thickness of 45 nm was deposited on one end of the conductive surface of the ITO conductive glass 1 using an electron beam evaporation apparatus, while maintaining a vacuum level of 6.7 × 10⁻⁶ in the electron beam evaporation apparatus. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at For backup.

[0092] Step 3: Construct thin film electrode 6 on the surface of p-GaN thin film 7:

[0093] (1) The p-GaN thin film 7 was grown on the sapphire substrate 8 using the MBE method, with a hole concentration of 10. 18 / cm 3 Hole mobility is 150cm 2 / V·s, with a thickness of 350μm.

[0094] (2) Take a 5mm×10mm (length×width) p-GaN film 7 and place it in acetone, ethanol and deionized water in sequence. Clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0095] (3) Using an electron beam evaporation apparatus, Ni thin film electrodes with a thickness of 30 nm and Au thin film thickness of 30 nm were sequentially deposited on one end of the p-GaN thin film 7, while maintaining a vacuum degree of 6.7 × 10⁻⁶. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at A thin film electrode 6 with a thickness of 60 nm was obtained for later use.

[0096] Step 4: Deposit an MgO electron blocking layer 4 on the surface of the p-GaN thin film 7: The thin film electrode 6 is blocked with a mask, and a 20 nm thick MgO electron blocking layer 4 is deposited on the surface of the p-GaN thin film 7 using an electron beam evaporator, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0097] Step 5: Deposit an MgO insulating layer 3 on the surface of the MgO electron blocking layer 4: Use a mask to cover the portion of the thin film electrode 6 and the p-GaN thin film 7 surface where the n-AgNWs@ZnO:Ga microwire 5 will be placed, with a width of approximately 30 μm. Use an electron beam evaporator to deposit a 3 μm thick MgO insulating layer 3 on the surface of the p-GaN thin film 7, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0098] Step 6: Spin-coating Ag nanowires onto the surface of ZnO:Ga microwires: Select a smooth ZnO:Ga microwire, fix the ZnO:Ga microwire to the glass slide surface using indium (In) particles, and uniformly spin-coat Ag nanowires onto the surface of the ZnO:Ga microwire using a spin-coating method to obtain n-AgNWs@ZnO:Ga microwire 5, for later use. The electron concentration of the n-AgNWs@ZnO:Ga microwire is 10. 17 / cm 3 The electron mobility is 150 cm⁻¹ 2 / V·s.

[0099] Step 7: Use tweezers to place the n-AgNWs@ZnO:Ga microwire 5 in the position blocked in step 5, ensuring that the n-AgNWs@ZnO:Ga microwire 5 is in close contact with the MgO electron blocking layer 4;

[0100] Step 8: Cover the conductive surface of the ITO conductive glass 1 with Au thin film electrode 2 obtained in step 2 onto the surface of the n-AgNWs@ZnO:Ga microwire 5, and clamp the entire device with two metal clips.

[0101] Example 4

[0102] A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires includes the following steps:

[0103] Step 1: Fabrication of gallium-doped zinc oxide microwires (ZnO:Ga MW):

[0104] (1) Use an electronic balance to weigh a specific weight of high-purity ZnO powder, gallium oxide powder and carbon powder, and grind and mix them in a mass ratio of 9:1:10. After the mixture is fully ground, put it into a bottle for later use.

[0105] (2) Take 6 grams of mixed powder into a corundum boat and place it into the heating zone of a dual-temperature zone high-temperature tube furnace;

[0106] (3) Open the argon (Ar) valve connected to the high-temperature tube furnace, set the gas flow rate to 112 sccm, and then start the high-temperature tube furnace heating program to raise the temperature to 1130 degrees Celsius at a rate of 18 degrees Celsius per minute.

[0107] (4) After the temperature rises to 1130 degrees Celsius and the reactants are heated stably for 32 minutes, the oxygen (O2) valve connected to the high-temperature tube furnace is opened, the gas flow rate is set to 18 sccm and the heating continues for 23 minutes.

[0108] (5) When the reaction time is over, turn off the high-temperature tube furnace and let it cool to room temperature naturally. Take out the corundum boat and obtain a ZnO:Ga microwire with a quadrilateral cross-section, a side length of 13μm and a length of 1cm, for later use.

[0109] Step 2: Construct Au thin film electrode 2 on the conductive surface of ITO conductive glass 1:

[0110] (1) Place ITO conductive glass 1 in acetone, ethanol and deionized water in sequence, clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0111] (2) An Au thin film electrode 2 with a width of 5 mm and a thickness of 43 nm was deposited on one end of the conductive surface of the ITO conductive glass 1 using an electron beam evaporation apparatus, while maintaining a vacuum level of 6.7 × 10⁻⁶ in the electron beam evaporation apparatus. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at For backup.

[0112] Step 3: Construct thin film electrode 6 on the surface of p-GaN thin film 7:

[0113] (1) The p-GaN thin film 7 was grown on the sapphire substrate 8 using the MBE method, with a hole concentration of 10. 19 / cm 3 Hole mobility is 50cm 2 / V·s, with a thickness of 320μm.

[0114] (2) Take a 5mm×10mm (length×width) p-GaN film 7 and place it in acetone, ethanol and deionized water in sequence. Clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0115] (3) Using an electron beam evaporation apparatus, Ni thin film electrodes with a thickness of 35 nm and Au thin film thickness of 35 nm were sequentially deposited on one end of the p-GaN thin film 7, while maintaining a vacuum degree of 6.7 × 10⁻⁶. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at A thin film electrode 6 with a thickness of 70 nm was obtained for later use.

[0116] Step 4: Deposit an MgO electron blocking layer 4 on the surface of the p-GaN thin film 7: The thin film electrode 6 is blocked with a mask, and an 11 nm thick MgO electron blocking layer 4 is deposited on the surface of the p-GaN thin film 7 using an electron beam evaporator, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0117] Step 5: Deposit an MgO insulating layer 3 on the surface of the MgO electron blocking layer 4: Use a mask to cover the portion of the thin film electrode 6 and the p-GaN thin film 7 surface where the n-AgNWs@ZnO:Ga microwire 5 will be placed, with a width of approximately 30 μm. Use an electron beam evaporator to deposit a 1 μm thick MgO insulating layer 3 on the surface of the p-GaN thin film 7, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0118] Step 6: Spin-coating Ag nanowires onto the surface of ZnO:Ga microwires: Select a smooth ZnO:Ga microwire, fix the ZnO:Ga microwire to the glass slide surface using indium (In) particles, and uniformly spin-coat Ag nanowires onto the surface of the ZnO:Ga microwire using a spin-coating method to obtain n-AgNWs@ZnO:Ga microwire 5, for later use. The electron concentration of the n-AgNWs@ZnO:Ga microwire is 10. 18 / cm 3 The electron mobility is 30 cm⁻¹ 2 / V·s.

[0119] Step 7: Use tweezers to place the n-AgNWs@ZnO:Ga microwire 5 in the position blocked in step 5, ensuring that the n-AgNWs@ZnO:Ga microwire 5 is in close contact with the MgO electron blocking layer 4;

[0120] Step 8: Cover the conductive surface of the ITO conductive glass 1 with Au thin film electrode 2 obtained in step 2 onto the surface of the n-AgNWs@ZnO:Ga microwire 5, and clamp the entire device with two metal clips.

[0121] Example 5

[0122] A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires includes the following steps:

[0123] Step 1: Fabrication of gallium-doped zinc oxide microwires (ZnO:Ga MW):

[0124] (1) Use an electronic balance to weigh a specific weight of high-purity ZnO powder, gallium oxide powder and carbon powder, and grind and mix them in a mass ratio of 9:1:10. After the mixture is fully ground, put it into a bottle for later use.

[0125] (2) Take 6 grams of mixed powder into a corundum boat and place it into the heating zone of a dual-temperature zone high-temperature tube furnace;

[0126] (3) Open the argon (Ar) valve connected to the high-temperature tube furnace, set the gas flow rate to 118 sccm, and then start the high-temperature tube furnace heating program to raise the temperature to 1140 degrees Celsius at a rate of 19 degrees Celsius per minute.

[0127] (4) After the temperature rises to 1140 degrees Celsius and the reactants are heated stably for 37 minutes, the oxygen (O2) valve connected to the high-temperature tube furnace is opened, the gas flow rate is set to 19 sccm and the heating continues for 27 minutes.

[0128] (5) When the reaction time is over, turn off the high-temperature tube furnace and let it cool to room temperature naturally. Take out the corundum boat and obtain ZnO:Ga microwires with a quadrilateral cross-section, a side length of 16μm and a length of 3cm, for later use.

[0129] Step 2: Construct Au thin film electrode 2 on the conductive surface of ITO conductive glass 1:

[0130] (1) Place ITO conductive glass 1 in acetone, ethanol and deionized water in sequence, clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0131] (2) An Au thin film electrode 2 with a width of 5 mm and a thickness of 49 nm was deposited on one end of the conductive surface of the ITO conductive glass 1 using an electron beam evaporation apparatus, while maintaining a vacuum level of 6.7 × 10⁻⁶ in the electron beam evaporation apparatus. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at For backup.

[0132] Step 3: Construct thin film electrode 6 on the surface of p-GaN thin film 7:

[0133] (1) The p-GaN thin film 7 was grown on the sapphire substrate 8 using the MBE method, with a hole concentration of 10. 18 / cm 3 Hole mobility is 100cm 2 / V·s, with a thickness of 340μm.

[0134] (2) Take a 5mm×10mm (length×width) p-GaN film 7 and place it in acetone, ethanol and deionized water in sequence. Clean it with an ultrasonic cleaner for 15 minutes, and then blow off the surface moisture with nitrogen.

[0135] (3) Using an electron beam evaporation apparatus, Ni and Au thin film electrodes with a thickness of 40 nm were sequentially deposited at one end of the p-GaN thin film 7, while maintaining a vacuum degree of 6.7 × 10⁻⁶. -4 Pa, electron beam current controlled at 0.96 mA, growth rate controlled at A thin film electrode 6 with a thickness of 80 nm was obtained for later use.

[0136] Step 4: Deposit an MgO electron blocking layer 4 on the surface of the p-GaN thin film 7: The thin film electrode 6 is blocked with a mask, and an 18 nm thick MgO electron blocking layer 4 is deposited on the surface of the p-GaN thin film 7 using an electron beam evaporator, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0137] Step 5: Deposit an MgO insulating layer 3 on the surface of the MgO electron blocking layer 4: Use a mask to cover the portion of the thin film electrode 6 and the p-GaN thin film 7 surface where the n-AgNWs@ZnO:Ga microwire 5 will be placed, with a width of approximately 30 μm. Use an electron beam evaporator to deposit a 3 μm thick MgO insulating layer 3 on the surface of the p-GaN thin film 7, maintaining a vacuum level of 3.0 × 10⁻⁶ in the electron beam evaporator. -4 Pa, electron beam current controlled at 0.85 mA, growth rate controlled at For backup.

[0138] Step 6: Spin-coating Ag nanowires onto the surface of ZnO:Ga microwires: Select a smooth ZnO:Ga microwire, fix the ZnO:Ga microwire to the glass slide surface using indium (In) particles, and uniformly spin-coat Ag nanowires onto the surface of the ZnO:Ga microwire using a spin-coating method to obtain n-AgNWs@ZnO:Ga microwire 5, for later use. The electron concentration of the n-AgNWs@ZnO:Ga microwire is 10. 19 / cm 3 The electron mobility is 110 cm⁻¹ 2 / V·s.

[0139] Step 7: Use tweezers to place the n-AgNWs@ZnO:Ga microwire 5 in the position blocked in step 5, ensuring that the n-AgNWs@ZnO:Ga microwire 5 is in close contact with the MgO electron blocking layer 4;

[0140] Step 8: Cover the conductive surface of the ITO conductive glass 1 with Au thin film electrode 2 obtained in step 2 onto the surface of the n-AgNWs@ZnO:Ga microwire 5, and clamp the entire device with two metal clips.

[0141] Of the above embodiments, Embodiment 1 is the best embodiment.

[0142] Comparative Example 1

[0143] The remaining steps of this comparative example are the same as those in Example 1, except that the MgO insulating layer 3 is replaced with a CaO insulating layer, and the MgO electron blocking layer 4 is replaced with a CaO electron blocking layer. The results showed that CaO is a relatively reactive compound that can undergo chemical reactions or react with other components under certain conditions, leading to corrosion, oxidation, or degradation, and impairing the performance and lifespan of the device.

[0144] Comparative Example 2

[0145] The remaining steps of this comparative example are the same as in Example 1, except that the n-AgNWs@ZnO:Ga microwire 5 is replaced with an n-AgNWs@CuO:Ga microwire. The results showed that copper oxide (CuO) has a lower conductivity than zinc oxide (ZnO). Therefore, replacing ZnO with CuO may lead to a decrease in the overall conductivity of the microwire, thereby limiting the current transport capability and performance of the device.

[0146] Comparative Example 3

[0147] The remaining steps in this comparative example are the same as in Example 1, except that the MgO electron blocking layer was not used. The results showed that, due to the absence of the MgO electron blocking layer, electron backflow could not be prevented, leading to electron-hole recombination and reduced photocurrent generation. Simultaneously, due to defects such as cracks and pinholes in the material itself, the dark current of the device increased significantly, impairing its performance and lifespan.

[0148] Comparative Example 4

[0149] The remaining steps in this comparative example are the same as in Example 1, except that AgNWs were not used; instead, the n-AgNWs@ZnO:Ga microwire 5 was replaced with an n-ZnO:Ga microwire. The results showed that, due to the lack of enhancement of electron mobility and electron concentration by AgNWs, the light transmission efficiency in the device was low, the photocurrent was reduced, and the response speed was slow.

[0150] Comparative Example 5

[0151] The remaining steps in this comparative example are the same as in Example 1, except that the Ga-doped ZnO microwires are replaced with undoped ZnO microwires. The results showed that without Ga doping, the electrical properties, thermal stability, and radiation resistance of the ZnO microwires were significantly weakened, and the photoelectric conversion efficiency decreased.

Claims

1. A self-driven ultraviolet photodetector based on Ga-doped ZnO microwires, characterized in that: The device includes a conductive glass (1), on which an Au thin film electrode (2), an MgO insulating layer (3) and an n-AgNWs@ZnO:Ga microwire (5) are disposed. The n-AgNWs@ZnO:Ga microwire (5) is disposed between the MgO insulating layer (3). An electron blocking layer (4) is disposed on the side of the MgO insulating layer (3) and the n-AgNWs@ZnO:Ga microwire (5) away from the conductive glass (1). The electron blocking layer (4) is connected to a p-GaN thin film (7). A thin film electrode (6) is disposed on the side of the p-GaN thin film (7) facing the electron blocking layer (4), and a substrate (8) is disposed on the side away from the electron blocking layer (4). The preparation method of the n-AgNWs@ZnO:Ga microwire (5) is as follows: select a smooth ZnO:Ga microwire, fix the ZnO:Ga microwire to the surface of the glass slide using indium particles, and uniformly spin-coat the Ag nanowire onto the surface of the ZnO:Ga microwire using a spin-coating method to obtain the n-AgNWs@ZnO:Ga microwire (5).

2. The self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 1, characterized in that: The Au thin film electrode (2) has a thickness of 40~50 nm, the MgO insulating layer (3) has a thickness of 1~3 μm, the electron blocking layer (4) has a thickness of 10~20 nm, and the thin film electrode (6) has a thickness of 50~100 nm.

3. A self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 1, characterized in that: The ZnO:Ga microwires in the n-AgNWs@ZnO:Ga microwires (5) have a length of 1~3 cm, a side length of 10~20 µm, and a quadrilateral cross-section.

4. A self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 1, characterized in that: The p-GaN thin film (7) has a thickness of 300~350 μm and a hole concentration of 10. 18 ~10 19 / cm 3 Hole mobility is 20-150 cm. 2 / V·s.

5. A self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 1, characterized in that: The electron blocking layer (4) is an MgO electron blocking layer, the thin film electrode (6) is a Ni and Au composite thin film electrode, and the substrate (8) is a sapphire substrate.

6. A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires, characterized in that, Includes the following steps: Step 1: Deposit Au thin film electrode (2) at one end of the conductive surface of the conductive glass (1). Step 2: Deposit a thin film electrode (6) at one end of the surface of the p-GaN thin film (7). Step 3: Use a mask to cover the thin film electrode (6) and deposit an electron blocking layer (4) on the other end of the p-GaN thin film (7). Step 4: Use a mask to cover the area on the surface of the thin film electrode (6) and the p-GaN thin film (7) that is intended for subsequent placement of n-AgNWs@ZnO:Ga microwires (5), and deposit an MgO insulating layer (3) on the surface of the MgO electron blocking layer (4). Step 5: Spin-coat AgNWs uniformly onto the surface of Ga-doped ZnO microwires to obtain n-AgNWs@ZnO:Ga microwires (5). Step 6: Place the n-AgNWs@ZnO:Ga microwire (5) at the position blocked in step 4; Step 7: Cover the conductive surface of the conductive glass (1) obtained in Step 1 onto the surface of the n-AgNWs@ZnO:Ga microwire (5).

7. The method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 6, characterized in that: In step one, the conductive glass (1) is placed in acetone, ethanol and deionized water in sequence before vapor deposition, ultrasonically cleaned, and then the surface moisture is blown off with nitrogen.

8. A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 6, characterized in that: In step two, the p-GaN thin film (7) is grown on the substrate (8) using molecular beam epitaxy, with a hole concentration of 10. 18 ~10 19 / cm 3 Hole mobility is 20-150 cm. 2 / V·s, placed in acetone, ethanol and deionized water in sequence, ultrasonically cleaned, and then the surface moisture was blown off with nitrogen. Ni and Au were deposited in sequence at one end of the p-GaN thin film (7) to obtain the thin film electrode (6).

9. A method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 6, characterized in that: In step five, the method for preparing Ga-doped ZnO microwires is as follows: ZnO powder, gallium oxide powder, and carbon powder are ground and mixed in a mass ratio of 9:1:10, placed in a high-temperature tube furnace and heated. The gas flow rate is set to 110~120 sccm, and the temperature is increased to 1100~1150 degrees Celsius at a rate of 15~20 degrees Celsius per minute. After reacting for 30~40 minutes, the oxygen valve connected to the high-temperature tube furnace is opened, the gas flow rate is set to 15~20 sccm, and heating is continued for 20~30 minutes.

10. The method for fabricating a self-driven ultraviolet photodetector based on Ga-doped ZnO microwires according to claim 6, characterized in that: In step five, the Ga-doped ZnO microwires are fixed to the glass slide by indium particles, and the Ag nanowires are uniformly spin-coated on the surface of the Ga-doped ZnO microwires.

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