A pn junction type gallium oxide-based self-powered ultraviolet detector and a preparation method thereof

Abstract

The application belongs to the technical field of photoelectric detectors, and particularly relates to a pn junction type gallium oxide-based self-powered ultraviolet detector and a preparation method thereof. The detector comprises a substrate, a p-Cr2O3 layer, an n-Ga2O3 layer, a double-layer graphene layer, a first metal electrode and a second metal electrode. The p-Cr2O3 layer is located on one side of the substrate, the area of the n-Ga2O3 layer is smaller than that of the p-Cr2O3 layer, the n-Ga2O3 layer and the second metal electrode are both located on the side of the p-Cr2O3 layer away from the substrate, and the n-Ga2O3 layer and the second metal electrode do not directly contact each other. The double-layer graphene layer is located on the side of the n-Ga2O3 layer away from the p-Cr2O3 layer, and the first metal electrode is located on the side of the double-layer graphene layer away from the n-Ga2O3 layer. The p-Cr2O3 layer and the n-Ga2O3 layer form a Cr2O3 / Ga2O3 pn junction. The detector can work under 0V bias, has the characteristics of zero-power consumption for detecting ultraviolet light signals, and has wide applications in military and civilian fields such as missile tracking, ultraviolet communication and corona monitoring.

Description

Technical Field

[0001] This invention belongs to the field of photodetector technology, specifically relating to a pn junction type gallium oxide-based self-powered ultraviolet detector and its fabrication method. Technical Background

[0002] Ultraviolet (UV) photodetectors have many important applications, such as space-to-space UV communication, missile plume detection and tracking, flame detection, ozone layer monitoring, high-voltage corona monitoring, and maritime search and rescue. Traditional UV photodetectors typically require an external power supply to achieve the desired light response. This not only significantly increases the size and energy consumption of the equipment but also greatly limits their long-term application in hazardous or harsh environments, such as outer space and unmanned vehicles. Self-powered UV detectors offer significant advantages in environments without an external power source.

[0003] Generally, self-powered ultraviolet detectors operate on the traditional photovoltaic effect, achieved through the construction of Schottky junctions, pn junctions, and heterojunctions. Among these, pn junction devices can rapidly separate and transport photogenerated carriers to the corresponding electrodes using a built-in electric field, enabling a fast response to incident light. Ga2O3 is a novel wide-bandgap semiconductor material with excellent chemical and thermal stability, and it often exhibits n-type conductivity, allowing it to form pn junctions with p-type semiconductor materials. Summary of the Invention

[0004] The purpose of this invention is to provide a pn junction gallium oxide-based self-powered ultraviolet detector and its fabrication method. This detector can operate at a 0V bias voltage and has the characteristic of zero-power detection of ultraviolet light signals.

[0005] To address the aforementioned technical problems, this invention provides a pn junction type gallium oxide-based self-powered ultraviolet detector, comprising a substrate, a p-Cr2O3 layer, an n-Ga2O3 layer, a bilayer graphene layer, a first metal electrode, and a second metal electrode. The p-Cr2O3 layer is located on one side of the substrate, and the area of ​​the n-Ga2O3 layer is smaller than that of the p-Cr2O3 layer. Both the n-Ga2O3 layer and the second metal electrode are located on the side of the p-Cr2O3 layer facing away from the substrate, and the n-Ga2O3 layer and the second metal electrode are not in direct contact. The bilayer graphene layer is located on the side of the n-Ga2O3 layer facing away from the p-Cr2O3 layer, and the first metal electrode is located on the side of the bilayer graphene layer facing away from the n-Ga2O3 layer. The p-Cr2O3 layer and the n-Ga2O3 layer form a Cr2O3 / Ga2O3 pn junction.

[0006] The thickness of the p-Cr2O3 layer is 500 nm to 10 μm. The p-Cr2O3 layer is grown on the substrate by magnetron sputtering. The sputtering pressure is in the range of 1.0 to 3.0 Pa, the sputtering power is in the range of 100 W to 300 W, the sputtering gas flow ratio O2 / Ar = 0% to 100%, the sputtering time is in the range of 1 h to 10 h, and the sputtering temperature is room temperature.

[0007] The thickness of the n-Ga2O3 layer is 20nm to 500nm. The n-Ga2O3 layer is grown on the p-Cr2O3 layer by magnetron sputtering. The sputtering pressure is in the range of 1.0 to 3.0 Pa, the sputtering power is in the range of 50W to 300W, the sputtering gas Ar flow rate is 5sccm to 20sccm, the sputtering time is in the range of 0.1h to 4h, and the sputtering temperature is room temperature.

[0008] The substrate can be a flexible substrate or a rigid substrate.

[0009] The first metal electrode and the second metal electrode are any one or a combination of several of Au, Pt, Ag, In, Ti, Ni and Cu.

[0010] The present invention also includes a second technical solution, a method for preparing the above-mentioned pn junction type gallium oxide-based self-powered ultraviolet detector, comprising the following steps:

[0011] (1) Continuous graphene was grown on both surfaces of copper foil by chemical vapor deposition. PMMA with a concentration range of 10-100 mg / ml was spin-coated on one side of the graphene surface using a spin coater. After spin coating, the graphene was placed on a constant temperature table and baked at 168-172℃ for 5-6 minutes and then dried.

[0012] (2) Place the uncoated PMMA graphene surface in a plasma cleaner for 1-2 min to remove the uncoated PMMA graphene on the copper foil. Then, etch the copper foil in a FeCl3 solution with a concentration range of 1-10 mol / L for 25-35 min. After etching, transfer it to deionized water for 8-12 min. Then, transfer it to a FeCl3 solution with a concentration range of 1-10 mol / L to etch the remaining copper foil for 2-2.5 h to remove the flocculent material on the copper foil. After the copper foil is completely etched, transfer it to deionized water to clean the remaining FeCl3 etching solution. Then, transfer it to dilute hydrochloric acid to further clean the remaining FeCl3 etching solution and other impurities on its surface to obtain bilayer graphene / PMMA.

[0013] (3) A p-Cr2O3 layer is formed on the substrate by magnetron sputtering;

[0014] (4) Part of the p-Cr2O3 layer is shielded, and an n-Ga2O3 layer is magnetron sputtered on the p-Cr2O3 layer to form a Cr2O3 / Ga2O3pn junction. The Cr2O3 / Ga2O3pn junction is then hydrophilically treated, and graphene / PMMA is retrieved from the Cr2O3 / Ga2O3pn junction and transferred to the Cr2O3 / Ga2O3pn junction.

[0015] (5) After air-drying the sample obtained in step (4) for 8 hours, place it on a constant temperature table to completely dry the sample, and then put it into a dichloromethane solution at 40°C to remove the PMMA adhesive, thereby obtaining a substrate-based Cr2O3 / Ga2O3pn junction / graphene composite.

[0016] (6) Fabricate a first metal electrode and a second metal electrode on the graphene surface and the n-Ga2O3 layer.

[0017] Specifically, a p-Cr2O3 layer is generated by magnetron sputtering, with sputtering pressure in the range of 1.0 to 3.0 Pa, sputtering power in the range of 100 W to 300 W, sputtering gas flow ratio O2 / Ar = 0% to 100%, sputtering time in the range of 1 h to 10 h, and sputtering temperature at room temperature.

[0018] Specifically, an n-Ga2O3 layer was magnetron sputtered onto a p-Cr2O3 layer. The sputtering pressure was in the range of 1.0 to 3.0 Pa, the sputtering power was in the range of 50 W to 300 W, the sputtering gas Ar flow rate was 5 sccm to 20 sccm, the sputtering time was in the range of 0.1 h to 4 h, and the sputtering temperature was room temperature.

[0019] The first and second metal electrodes are fabricated by sputtering, thermal evaporation, spin coating, or pressing.

[0020] The first metal electrode and the second metal electrode are any one or a combination of several of Au, Pt, Ag, In, Ti, Ni and Cu.

[0021] The advantages and beneficial effects of this invention are as follows:

[0022] (1) The pn-junction gallium oxide-based self-powered ultraviolet detector of the present invention can operate at 0V bias voltage and has the characteristic of zero-power detection of ultraviolet light signals. It has wide applications in military and civilian fields such as missile tracking, ultraviolet communication, and corona monitoring, and can work for a long time in environments without external power sources, such as outer space and the North and South Poles. In the embodiments of the present invention, the bilayer graphene has high transmittance and high conductivity to ultraviolet / extreme ultraviolet light. The embodiments of the present invention improve the conductivity of the electrode and reduce the power consumption of the detector by using a composite electrode made of bilayer graphene and a first metal electrode.

[0023] (2) The fabrication method of the pn-junction gallium oxide-based self-powered ultraviolet detector of the present invention is simple, employs a low-cost magnetron sputtering method, and prepares p-type Cr2O3 and n-type Ga2O3 thin films at room temperature. It offers advantages such as low cost, strong process controllability, ease of operation, good repeatability, and large-area fabrication capability. Furthermore, both materials are oxide semiconductors with matched structures. Graphene is a crystal composed of a single atomic layer of tightly packed carbon atoms. It exhibits high optical transmittance and excellent electrical conductivity in the ultraviolet-visible band, which can improve the photoelectric response performance of the device. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a pn junction type gallium oxide-based self-powered ultraviolet detector according to an embodiment of the present invention;

[0025] Figure 2 This is an IV curve of the pn junction gallium oxide-based self-powered ultraviolet detector of the present invention under 254nm ultraviolet light irradiation;

[0026] Figure 3 This is the IT response curve of the pn junction gallium oxide-based self-powered ultraviolet detector of the present invention to 254nm ultraviolet light of different intensities under a 0V bias voltage;

[0027] Figure 4 This embodiment of the invention describes a pn-junction gallium oxide-based self-powered ultraviolet detector with a bias voltage of 0V and a power output of 2500 μW / cm. 2 IT curve and response time fitting of 254nm ultraviolet light intensity. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments, but these are not intended to limit the scope of the invention. Unless otherwise specified, the means used in the embodiments are conventional means in the art.

[0029] Example 1:

[0030] A method for fabricating a pn junction type gallium oxide-based self-powered ultraviolet detector is as follows:

[0031] (1) Cut the purchased 2-inch (0001) faceted sapphire into 10×10mm pieces. 2 The samples were then ultrasonically cleaned for 10 minutes each with acetone, anhydrous ethanol, and deionized water, and then dried in an oven.

[0032] (2) The cleaned and dried substrate was placed in the sputtering chamber and a p-Cr2O3 thin film was grown by magnetron sputtering. The specific parameters are as follows: the back vacuum is 3.0 × 10⁻⁶. -4The working atmosphere was vacuum, the sputtering pressure was 2.0 Pa, the substrate temperature was room temperature, the sputtering gas ratio was Ar / O2 = 24 / 16, the sputtering power was 300 W, the target spacing was 8 cm, and the sputtering time was 5 h.

[0033] (3) Using the p-Cr2O3 layer deposited on the (0001) facet sapphire substrate prepared above as the substrate, an n-Ga2O3 thin film was grown by magnetron sputtering in a magnetron sputtering chamber (half of the substrate area was covered by a sapphire sheet during the growth process) to prepare a Cr2O3 / Ga2O3pn junction. The specific parameters are as follows: background vacuum is 3.0 × 10⁻⁶. -4 The working atmosphere was vacuum, the sputtering pressure was 1.0 Pa, the substrate temperature was room temperature, the sputtering gas was 10 sccm of Ar, the sputtering power was 200 W, the target spacing was 5 cm, and the sputtering time was 2 h.

[0034] (4) Continuous graphene was grown on a copper foil with a thickness of 24-25 μm by chemical vapor deposition. A 100 mg / ml concentration of PMMA was spin-coated onto the graphene surface using a spin coater. After spin coating, the graphene was placed on a constant temperature table and baked at 168-172 °C for 5-6 min.

[0035] (5) After drying, place the uncoated PMMA side into a plasma cleaner for 1-2 minutes to remove the double-layer graphene on the copper foil on the back side. Then, etch the copper foil in a 5 mol / L FeCl3 solution for 25-35 minutes. After etching, transfer it to deionized water for 8-12 minutes. Then, transfer it to a new 5 mol / L FeCl3 solution to etch the remaining copper foil for 2-2.5 hours to remove the flocculent material on the copper foil. After the copper foil is completely etched, transfer it to deionized water to clean the remaining FeCl3 etching solution. Then, transfer it to dilute hydrochloric acid to further clean the remaining FeCl3 etching solution and other impurities on its surface.

[0036] (6) After cleaning, the Cr2O3 / Ga2O3 base is hydrophilically treated, and then used to retrieve bilayer graphene and transfer the bilayer graphene to the Cr2O3 / Ga2O3pn junction.

[0037] (7) After air-drying the sample obtained in step (6) for 8 hours, place it on a constant temperature table to bake the sample completely dry, and then put it into a dichloromethane solution at 40°C to remove the PMMA adhesive.

[0038] (8) An Ag electrode with a diameter of about 2 mm is prepared on the double graphene layer and Cr2O3 layer obtained in step (7) by drop coating and connected to the Cu line as the external electrode of the Cr2O3 / Ga2O3pn junction.

[0039] The above method can be used to prepare a self-powered ultraviolet detector based on an Ag / bilayer graphene layer / Cr2O3 / Ga2O3 / Agpn junction, such as... Figure 1 As shown, in this self-powered ultraviolet detector, p-Cr2O3 is connected to the positive electrode and n-Ga2O3 is connected to the negative electrode. Under ±5V bias and 254nm ultraviolet light irradiation, it exhibits obvious rectification characteristics, such as... Figure 2 As shown, the rectification ratio is I. 254nm (5V) / I 254nm (-5V)=2.56μA / -0.62μA≈4.13. For example... Figure 3 As shown, under 0V bias and 254nm illumination, the photocurrent increases significantly, and the photocurrent also increases with the increase of illumination intensity, exhibiting self-powered characteristics. Figure 4 At 0V bias, 2500μW / cm 2 Fitting curve under illumination intensity, rise time τ r and decay time τ d The measurements were taken at 0.34 s and 3.65 s, respectively, at a voltage of 0 V. The instantaneous change in current indicates that the detector has high sensitivity under 254 nm ultraviolet light irradiation in the solar blind zone.

[0040] Example 2

[0041] The substrate in Example 1 was changed to an ITO substrate. In this application, the ITO substrate is a flexible substrate. A Cr2O3 / Ga2O3pn junction self-powered ultraviolet detector based on the ITO substrate was fabricated. The IT curve was measured at 0V. It was found that the current changed instantaneously when the ultraviolet lamp was switched on and off, indicating that the detector has high sensitivity to 254nm ultraviolet light.

[0042] Example 3

[0043] In Example 1, the Cr2O3 growth was changed from sputtering gas to pure Ar sputtering, thus obtaining Cr2O 3 / The Ga2O3pn junction self-powered ultraviolet detector's IT curve was measured at 0V. It was found that the current changed instantaneously when the ultraviolet lamp was switched on, indicating that the detector has high sensitivity to 254nm ultraviolet light.

[0044] Example 4

[0045] A method for fabricating a pn junction type gallium oxide-based self-powered ultraviolet detector is as follows:

[0046] (1) Continuous bilayer graphene was grown on the surface of a copper foil with a thickness of 24-25 μm by chemical vapor deposition. A concentration of 100 mg / ml PMMA was spin-coated onto the surface of the bilayer graphene using a spin coater. After spin coating, the graphene was placed on a constant temperature table and baked at 168 °C for 5-6 min.

[0047] (2) After drying, place the uncoated PMMA side into a plasma cleaner for 1-2 minutes to remove the double-layer graphene on the copper foil on the back side. Then, etch the copper foil in a 1 mol / L FeCl3 solution for 35 minutes. After etching, transfer it to deionized water for 8 minutes. Then, transfer it to a new 1 mol / L FeCl3 solution to etch the remaining copper foil for 2 hours to remove the flocculent material on the copper foil. After the copper foil is completely etched, transfer it to deionized water to clean the remaining FeCl3 etching solution. Then, transfer it to dilute hydrochloric acid to further clean the remaining FeCl3 etching solution and other impurities on its surface.

[0048] (3) Cut the purchased 2-inch (0001) faceted sapphire into 10×10mm pieces. 2 The samples were then ultrasonically cleaned for 10 minutes each with acetone, anhydrous ethanol, and deionized water, and then dried in an oven.

[0049] (4) Place the cleaned and dried substrate into the sputtering chamber and grow a p-Cr2O3 thin film by magnetron sputtering. The specific parameters are as follows: background vacuum is 3.0 × 10⁻⁶. -4 The working atmosphere was vacuum, the sputtering pressure was 1.0 Pa, the substrate temperature was room temperature, the sputtering gas ratio was O2, the sputtering power was 100 W, the target spacing was 8 cm, and the sputtering time was 1 h.

[0050] (5) Using the p-Cr2O3 layer deposited on the (0001) facet sapphire substrate prepared above as a substrate, an n-Ga2O3 thin film was grown by magnetron sputtering in a magnetron sputtering chamber (half of the substrate area was covered by a sapphire sheet during the growth process) to prepare a Cr2O3 / Ga2O3pn junction. The specific parameters are as follows: background vacuum is 3.0 × 10⁻⁶. -4 The working atmosphere was vacuum, the sputtering pressure was 1.0 Pa, the substrate temperature was room temperature, the sputtering gas was 5 sccm of Ar, the sputtering power was 200 W, the target spacing was 5 cm, and the sputtering time was 0.1 h.

[0051] (6) After cleaning, the Cr2O3 / Ga2O3 base is hydrophilically treated, and then used to retrieve bilayer graphene and transfer the bilayer graphene to the Cr2O3 / Ga2O3pn junction.

[0052] (7) After air-drying the sample obtained in step (6) for 8 hours, place it on a constant temperature table to bake the sample completely dry, and then put it into a dichloromethane solution at 40°C to remove the PMMA adhesive.

[0053] (8) An Ag electrode with a diameter of about 2 mm is prepared on the bilayer graphene layer and the p-Cr2O3 layer obtained in step (7) by drop coating. The first Ag electrode and the bilayer graphene layer form a composite electrode as the upper electrode; the Ag electrode on the p-Cr2O3 layer serves as the second metal electrode.

[0054] Cr2O was prepared by the above method 3 / The Ga2O3pn junction self-powered ultraviolet detector's IT curve was measured at 0V. It was found that controlling the ultraviolet lamp switch caused an instantaneous change in current, indicating that the detector has high sensitivity to 254nm ultraviolet light. The test results are similar to those in Example 1.

[0055] Example 5

[0056] A method for fabricating a pn junction type gallium oxide-based self-powered ultraviolet detector is as follows:

[0057] (1) Continuous bilayer graphene was grown on the surface of a copper foil with a thickness of 24-25 μm by chemical vapor deposition. A concentration of 100 mg / ml PMMA was spin-coated onto the surface of the bilayer graphene using a spin coater. After spin coating, the graphene was placed on a constant temperature table and baked at 172 °C for 5-6 min.

[0058] (2) After drying, the side without PMMA spin coating is placed in a plasma cleaner for 1-2 minutes to remove the double-layer graphene on the copper foil on the back. Then, the PMMA / double-layer graphene layer / copper foil is placed in a 10 mol / L FeCl3 solution to etch the copper foil. After etching for 25 minutes, it is transferred to deionized water and soaked for 12 minutes. Then, it is transferred to a new 10 mol / L FeCl3 solution to etch the remaining copper foil for 2.5 hours to remove the flocculent material on the copper foil. After the copper foil is completely etched, it is transferred to deionized water to clean the remaining FeCl3 etching solution. Then, it is transferred to dilute hydrochloric acid to further clean the remaining FeCl3 etching solution and other impurities on its surface.

[0059] (3) Cut the purchased 2-inch (0001) faceted sapphire into 10×10mm pieces. 2 The samples were then ultrasonically cleaned for 10 minutes each with acetone, anhydrous ethanol, and deionized water, and then dried in an oven.

[0060] (4) Place the cleaned and dried substrate into the sputtering chamber and grow a p-Cr2O3 thin film by magnetron sputtering. The specific parameters are as follows: background vacuum is 3.0 × 10⁻⁶. -4The working atmosphere was vacuum, the sputtering pressure was 3.0 Pa, the substrate temperature was room temperature, the sputtering gas ratio was O2 / Ar = 19%~, the sputtering power was 100 W, the target spacing was 8 cm, and the sputtering time was 10 h.

[0061] (5) Using the p-Cr2O3 layer deposited on the (0001) facet sapphire substrate prepared above as a substrate, an n-Ga2O3 thin film was grown by magnetron sputtering in a magnetron sputtering chamber (half of the substrate area was covered by a sapphire sheet during the growth process) to prepare a Cr2O3 / Ga2O3pn junction. The specific parameters are as follows: background vacuum is 3.0 × 10⁻⁶. -4 The working atmosphere was vacuum, the sputtering pressure was 3.0 Pa, the substrate temperature was room temperature, the sputtering gas was 20 sccm of Ar, the sputtering power was 200 W, the target spacing was 5 cm, and the sputtering time was 4 h.

[0062] (6) After cleaning, the Cr2O3 / Ga2O3 base is hydrophilically treated, and then used to retrieve bilayer graphene and transfer the bilayer graphene to the Cr2O3 / Ga2O3pn junction.

[0063] (7) After air-drying the sample obtained in step (6) for 8 hours, place it on a constant temperature table to bake the sample completely dry, and then put it into a dichloromethane solution at 40°C to remove the PMMA adhesive.

[0064] (8) A Pt electrode is fabricated on the bilayer graphene layer and the p-Cr2O3 layer obtained in step (7) using magnetron sputtering. The diameter of the Pt electrode is 2 mm. The Pt electrode on the bilayer graphene layer is the first metal electrode, and the Pt electrode and the bilayer graphene layer form a composite electrode as the upper electrode. The Pt electrode on the p-Cr2O3 layer is the second metal electrode. In other embodiments, Au, In, Ti, Ni, or Cu electrodes, or any combination of one or more of them, can also be fabricated by thermal evaporation or pressing to serve as the first and second metal electrodes.

[0065] Cr2O was prepared by the above method 3 / The Ga2O3pn junction self-powered ultraviolet detector's IT curve was measured at 0V. It was found that controlling the ultraviolet lamp switch caused an instantaneous change in current, indicating that the detector has high sensitivity to 254nm ultraviolet light. The test results are similar to those in Example 1.

[0066] In other embodiments, steps (1) and (2) may occur after step (5), or step (3) may not be required.

[0067] Example 6

[0068] This application provides a pn junction type gallium oxide-based self-powered ultraviolet detector, which is prepared by the preparation method of the above embodiment. The detector includes a substrate 1, a p-Cr2O3 layer 2, an n-Ga2O3 layer 3, a bilayer graphene layer 41, a first metal electrode 42, and a second metal electrode 5. The p-Cr2O3 layer 2 is located on one side of the substrate 1, and the area of ​​the n-Ga2O3 layer 3 is smaller than the area of ​​the p-Cr2O3 layer 2. The n-Ga2O3 layer 3 and the second metal electrode 5 are both located on the side of the p-Cr2O3 layer 2 away from the substrate 1, and the n-Ga2O3 layer 3 and the second metal electrode 5 are not in direct contact. The bilayer graphene layer 41 is located on the side of the n-Ga2O3 layer 3 away from the p-Cr2O3 layer 2, and the first metal electrode 42 is located on the side of the bilayer graphene layer 41 away from the n-Ga2O3 layer. The p-Cr2O3 layer 2 and the n-Ga2O3 layer 3 form a Cr2O3 / Ga2O3 pn junction.

[0069] The pn-junction gallium oxide-based self-powered ultraviolet detector of this invention operates at 0V bias and features zero-power detection of ultraviolet light signals. It has wide applications in military and civilian fields such as missile tracking, ultraviolet communication, and corona monitoring, and can operate long-term in environments without external power sources, such as outer space and the Arctic / Antarctic regions. In this embodiment, the bilayer graphene exhibits high transmittance and high conductivity for ultraviolet / extreme ultraviolet light. This embodiment improves the conductivity of the electrode and reduces the power consumption of the detector by using a composite electrode made of bilayer graphene and a first metal electrode.

[0070] In this embodiment, the thickness of the p-Cr2O3 layer 2 is 500 nm to 10 μm. The p-Cr2O3 layer 2 is grown on the substrate 1 by magnetron sputtering. The sputtering pressure is in the range of 1.0 to 3.0 Pa, the sputtering power is in the range of 100 W to 300 W, the sputtering gas flow ratio O2 / Ar = 0% to 100%, the sputtering time is in the range of 1 h to 10 h, and the sputtering temperature is room temperature. Specifically, the thickness of the p-Cr2O3 layer 2 is 500 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 8 μm, or 10 μm, etc.

[0071] In this embodiment, the thickness of the n-Ga2O3 layer 3 is 20 nm to 500 nm. The n-Ga2O3 layer 3 is grown on the p-Cr2O3 layer 2 by magnetron sputtering. The sputtering pressure is in the range of 1.0 to 3.0 Pa, the sputtering power is in the range of 50 W to 300 W, the sputtering gas Ar flow rate is 5 sccm to 20 sccm, the sputtering time is in the range of 0.1 h to 4 h, and the sputtering temperature is room temperature. Specifically, the thickness of the n-Ga2O3 layer 3 is 20 nm, 50 nm, 100 nm, 200 nm, 30 nm, 400 nm, or 500 nm.

[0072] In this embodiment, substrate 1 is a rigid substrate, which can be sapphire or a flexible substrate.

[0073] In this embodiment, the first metal electrode 42 and the second metal electrode 5 are Ag, respectively. In this embodiment, the first metal electrode and the bilayer graphene form a bilayer graphene / Ag composite electrode. By using bilayer graphene and the first metal electrode to form a composite electrode, the conductivity of the electrode is improved and the power consumption of the detector is reduced. In other embodiments, the first metal electrode 42 and the second metal electrode 5 are any one or a combination of several of Au, Pt, In, Ti, Ni, and Cu. For example, the first metal electrode 42 and the second metal electrode 5 can be Pt / Au or Ag / Ti metal electrodes, respectively.

Claims

1. A pn-junction type gallium-oxide-based self-powered ultraviolet detector, characterized by, The application relates to a semiconductor device, which comprises a substrate, a p-Cr2O3 layer, an n-Ga2O3 layer, a double-layer graphene layer, a first metal electrode and a second metal electrode, wherein the p-Cr2O3 layer is located on one side of the substrate, the area of the n-Ga2O3 layer is smaller than that of the p-Cr2O3 layer, the n-Ga2O3 layer and the second metal electrode are both located on the side of the p-Cr2O3 layer away from the substrate, and the n-Ga2O3 layer and the second metal electrode do not directly contact each other; the double-layer graphene layer is located on the side of the n-Ga2O3 layer away from the p-Cr2O3 layer, and the first metal electrode is located on the side of the double-layer graphene layer away from the n-Ga2O3 layer; and the p-Cr2O3 layer and the n-Ga2O3 layer form a Cr2O3 / Ga2O3 pn junction. 2.The pn-junction gallium oxide-based self-powered ultraviolet detector according to claim 1, wherein, The thickness of the p-Cr2O3 layer is 500 nm to 10 microns, and the p-Cr2O3 layer is grown on the substrate by a magnetron sputtering method, wherein the sputtering pressure is in the range of 1.0 to 3.0 Pa, the sputtering power is in the range of 100 W to 300 W, the sputtering gas flow ratio O2 / Ar is 0% to 100%, the sputtering time is in the range of 1 h to 10 h, and the sputtering temperature is room temperature. 3.The pn-junction gallium oxide-based self-powered ultraviolet detector according to claim 1, wherein the n-type gallium oxide-based layer is a n-type gallium oxide-based layer with a thickness of 0.5-2.0 μm. The thickness of the n-Ga2O3 layer is 20 nm to 500 nm, and the n-Ga2O3 layer is grown on the p-Cr2O3 layer by a magnetron sputtering method, wherein the sputtering pressure is in the range of 1.0 to 3.0 Pa, the sputtering power is in the range of 50 W to 300 W, the sputtering gas Ar flow is 5 sccm to 20 sccm, the sputtering time is in the range of 0.1 h to 4 h, and the sputtering temperature is room temperature. 4.The pn-junction gallium oxide-based self-powered ultraviolet detector according to claim 1, wherein, The substrate is a flexible substrate or a rigid substrate.

5. The pn-junction gallium oxide based self-powered ultraviolet detector according to claim 1, wherein the gallium oxide based self-powered ultraviolet detector is a vertical structure. The first metal electrode and the second metal electrode are any one or a combination of Au, Pt, Ag, In, Ti, Ni and Cu.

6. A method for preparing the pn-junction type gallium oxide-based self-powered ultraviolet detector according to any one of claims 1 to 5, characterized by, The application further discloses a preparation method of the semiconductor device, which comprises the following steps: (1) growing continuous graphene on both surfaces of a copper foil by a chemical vapor deposition method, spin-coating PMMA with a concentration ranging from 10 to 100 mg / ml on the graphene surface of one of the surfaces by using a spin coater, and baking the PMMA / graphene layer on the constant temperature table at 168-172 DEG C for 5-6 min after the spin coating is completed; (2) placing the surface of the graphene without the spin-coated PMMA into a plasma cleaning machine for 1-2 min to remove the graphene on the copper foil without the PMMA, then placing the PMMA / double-layer graphene layer / copper foil into a FeCl3 solution with a concentration ranging from 1 to 10 mol / L to etch the copper foil, transferring the copper foil into deionized water for 8-12 min after etching for 25-35 min, then transferring the copper foil into the FeCl3 solution with a concentration ranging from 1 to 10 mol / L to etch the residual copper foil, removing the flocculation on the copper foil after etching for 2-2.5 h, transferring the copper foil into deionized water to clean the residual FeCl3 etching solution, and then transferring the copper foil into dilute hydrochloric acid to further clean the residual FeCl3 etching solution and other impurities on the surface, thereby obtaining the double-layer graphene / PMMA. (3) growing a p-Cr2O3 layer on the substrate by magnetron sputtering; (4) shielding part of the p-Cr2O3 layer, magnetron sputtering an n-Ga2O3 layer on the p-Cr2O3 layer to form a Cr2O3 / Ga2O3 pn junction, and performing a hydrophilic treatment on the Cr2O3 / Ga2O3 pn junction, then using the Cr2O3 / Ga2O3 pn junction to fish graphene / PMMA, and transferring the graphene / PMMA to the Cr2O3 / Ga2O3 pn junction; (5) after the sample obtained in step (4) is air-dried for 8 h, baking the sample completely on a constant temperature table, then putting the sample into a dichloromethane solution at 40℃ to remove the PMMA glue, and obtaining a Cr2O3 / Ga2O3 pn junction / graphene composite based on the substrate; (6) fabricating a first metal electrode and a second metal electrode on the graphene surface and the n-Ga2O3 layer.

7. The method of claim 6, wherein, The p-Cr2O3 layer is grown by magnetron sputtering, the sputtering pressure is in the range of 1.0-3.0 Pa, the sputtering power is in the range of 100 W-300 W, the sputtering gas flow ratio O2 / Ar is 0%-100%, the sputtering time is in the range of 1 h-10 h, and the sputtering temperature is room temperature.

8. The method of claim 6, wherein, The n-Ga2O3 layer is magnetron sputtered on the p-Cr2O3 layer, the sputtering pressure is in the range of 1.0-3.0 Pa, the sputtering power is in the range of 50 W-300 W, the sputtering gas Ar flow is 5-20 sccm, the sputtering time is in the range of 0.1 h-4 h, and the sputtering temperature is room temperature.

9. The method of claim 6, wherein, The first metal electrode and the second metal electrode are fabricated by sputtering, thermal evaporation, spin coating or pressing.

10. The method of claim 9, wherein, The first metal electrode and the second metal electrode are any one or a combination of several of Au, Pt, Ag, In, Ti, Ni and Cu.

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