Polarization sensitive type narrow-band solar blind self-driven photoelectric detector and preparation method thereof

Abstract

The invention discloses a polarization-sensitive narrow-band solar blind self-driven photoelectric detector and a preparation method thereof, and belongs to the technical field of semiconductor photoelectric devices. The detector comprises an n-type conductive single Ga2O3 micron wire, a p-type conductive GaN substrate, a PET substrate and a two-dimensional graphene film. According to the device, Ni / Au alloy is selected as a positive electrode, and a two-dimensional graphene film is used as a transparent window of ultraviolet solar blind light and a negative electrode of the device. By means of built-in potential formed by the n-Ga2O3 / p-GaN heterojunction and a Schottky barrier of Ga2O3 / Graphene, high-sensitivity detection of solar-blind ultraviolet light under the self-driving condition is achieved. The device has relatively high responsivity, specific detection rate and external quantum efficiency. The preparation method comprises the following steps: cleaning the GaN substrate, evaporating the Ni / Au electrode, adhering the PET substrate with the channel, transferring the Ga2O3 micron wire to form the heterojunction, and transferring and curing the graphene electrode. The device has the characteristics of polarization sensitivity and low power consumption, and can be applied to the fields of ultraviolet solar blind band encryption communication and environment monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a polarization-sensitive narrow-band solar-blind self-driven photoelectric detector and a preparation method thereof. Background Art

[0002] With the widespread use and rapid development of third-generation semiconductors, polarization detection devices have broad application prospects in fields such as bioimaging, military radar, and environmental monitoring. Currently, research on polarization detector detection bands focuses primarily on the visible and near-infrared ranges. Polarization detectors operating in the ultraviolet, especially the solar-blind band, are extremely scarce. Detectors in the solar-blind band offer the advantages of low noise, low false alarm rates, and high signal-to-noise ratios. They can also increase the amount of information about detected targets by combining spatial spectral and polarization information, reducing the impact of environmental interference on information transmission and thus enabling encrypted information transmission in complex environments. Therefore, it is of great significance to construct high-performance, solar-blind polarization detectors using suitable semiconductor materials.

[0003] With the continuous advancement of integrated circuit technology, the demand for device miniaturization, integration, and software-based design is increasing. However, existing optoelectronic devices in the ultraviolet solar-blind band are large in size, complex in fabrication, have limited functionality, and consume high power, presenting certain disadvantages in industrial applications. Therefore, it is of great significance to construct a multifunctional, self-driven, polarization-based solar-blind photodetector that is miniaturized, integrated, and unaffected by complex environments. Summary of the Invention

[0004] The present invention aims to address the above-mentioned problems and provides a polarization-sensitive, narrowband, solar-blind, self-driven photodetector and its preparation method. This invention constructs an effective pn structure using a single n-Ga2O3 micron wire and a p-GaN substrate, and uses a graphene electrode as the top transparent electrode. Graphene's extremely high transmittance in the deep ultraviolet band allows the Schottky barrier formed by the graphene electrode and the n-Ga2O3 micron wire to greatly facilitate the transmission, collection, and capture of photogenerated electrons. Under self-driven conditions (0V bias), high responsivity to ultraviolet light, high specific detectivity, and high external quantum efficiency are achieved. Furthermore, the graphene electrode exhibits excellent optical transparency and transmittance in the ultraviolet solar-blind band, significantly reducing losses in optical signal transmission and ensuring polarization sensitivity, rapid response, and stable performance in the ultraviolet solar-blind band. Furthermore, by integrating the device with a transimpedance amplifier and a single-chip microcontroller, the single-chip microcontroller rapidly analyzes the photocurrent signal generated by the detector, resulting in the device having the dual functions of photodetection and polarization-encrypted signal transmission.

[0005] The specific technical solution is as follows: To achieve the above purpose, the present invention adopts the following technical solution:

[0006] A polarization-sensitive, narrowband, solar-blind, self-driven photodetector comprises an n-Ga2O3 micron wire, a p-GaN substrate, a graphene electrode, a Ni / Au alloy electrode, and two PET (polyethylene terephthalate) substrates. The p-GaN substrate is plated with a Ni / Au alloy electrode on one short side. The two PET substrates are bonded to the p-GaN substrate surface, with a trench corresponding to the diameter of the n-Ga2O3 micron wire. The graphene electrode is partially adhered to the n-Ga2O3 micron wire, while the remaining portion is attached to the PET. The single n-Ga2O3 micron wire is located in the trench. After fabrication, the device is integrated with a transimpedance amplifier and a single-chip microcontroller, and the results are output via a program.

[0007] Furthermore, the p-GaN substrate has a thickness of 350 μm and an electron mobility of 2000 cm 2 / V·s; the thickness of the metal Ti / Au alloy electrode is 100nm, the thickness of Ni is 50nm, and the thickness of Au is 50nm; the thickness of the PET is 5μm.

[0008] Furthermore, the width of the channel is 15 μm, which is consistent with the diameter of a single sheet n-Ga2O3 micron wire; the sheet n-Ga2O3 micron wire has a diameter of 15 μm, a length of 0.5 to 0.6 cm, and an electron concentration of 10 18 / cm3, and the carrier mobility is 90cm 2 / V·s.

[0009] Furthermore, the graphene electrode has a thickness of 0.35 nm, a surface resistivity of 400-600 Ω / □, and a size of 0.4 cm×0.4 cm;

[0010] Furthermore, the PET substrate has a thickness of 4 μm and a size of 0.4 cm×0.3 cm.

[0011] The present invention also provides a method for preparing the polarization-sensitive narrow-band solar-blind self-driven photodetector, and the technical scheme adopted is as follows: 1) cleaning the p-GaN substrate; 2) using electron beam evaporation to evaporate Ni / Au alloy electrodes of the same thickness on the p-GaN, and annealing after the evaporation is completed; 3) under a 5X optical microscope, two PET substrates of the same thickness and size are transferred and pasted to the surface of the p-GaN substrate, leaving a trench in the middle that matches the diameter of the flaky n-Ga2O3 micron wire; 4) selecting high-quality crystalline , the flaky n-Ga2O3 micron wire with smooth surface and uniform size is transferred and pressed into the groove between two PET substrates, contacting with the p-GaN substrate to form a pn junction and constructing an n-Ga2O3 / p-GaN heterostructure; 5) the copper foil on the copper-based graphene standard is cleaned and dried to prepare a single-layer graphene electrode, which is transferred and tightly attached to the flaky n-Ga2O3 micron wire as the top transparent electrode, and then placed in an oven for curing to obtain a polarization-sensitive narrow-band solar-blind self-driven photodetector.

[0012] Furthermore, step 1) substrate cleaning: the p-GaN substrate is placed in a clean beaker, trichloroethylene is added to completely submerge it, and the p-GaN substrate is cleaned using an ultrasonic cleaner for 15 minutes. After cleaning, it is cleaned again using acetone, ethanol, and deionized water in an ultrasonic cleaner for 15 minutes each. Then, the residual liquid on the surface of the substrate is cleaned with high-purity nitrogen gas, and finally the cleaned p-GaN substrate is dried in a constant temperature drying oven at 80°C.

[0013] Furthermore, in step 2), a Ni / Au alloy electrode is deposited on the p-GaN substrate: a mask is used to cover the portion of the p-GaN substrate where no electrode is to be deposited, and a Ni film is deposited on the surface of the p-GaN substrate using electron beam evaporation at a deposition rate of 8 to 10 pm / s and a thickness of 50 nm. (S2) The target is replaced, and a further Au film is deposited on the surface of the deposited Ni film at a deposition rate of 8 to 10 pm / s and a thickness of 50 nm. A uniform Ni / Au alloy electrode with a thickness of 100 nm is then deposited on the exposed portion of the p-GaN substrate. The mask is removed, and the substrate is annealed in a tube furnace at 500°C for 10 to 15 minutes. After annealing, the Ni / Au electrode is tested for its IV characteristic curve.

[0014] Furthermore, step 4) is a method for constructing an n-Ga2O3 / p-GaN heterostructure: under a 5X optical microscope, a sheet of n-Ga2O3 micron wires is transferred to the surface of a p-GaN substrate with exposed channels left in PET (polyethylene terephthalate), and an In particle electrode is pressed on the surface of a metal Ni / Au alloy electrode to construct an n-Ga2O3 / p-GaN heterojunction structure.

[0015] Furthermore, in step 5), a single-layer graphene electrode is prepared by selecting a single-layer graphene film with a copper base on one side and a PMMA film spin-coated on the other side, dissolving metallic copper in a FeCl3 solution, transferring the graphene to a cleaned silica substrate, and allowing it to dry naturally. Acetone is then used to dissolve the PMMA and transfer the graphene to the device. Finally, the device is heated in an oven with the oven temperature set to 80°C and the curing time set to 120 to 150 minutes, so that the graphene is tightly attached to the upper end of the n-Ga2O3 micron wire as a top transparent electrode and does not directly contact the bottom electrode.

[0016] To further achieve the above objectives, the device comprises a polarization-sensitive, narrowband, solar-blind, self-driven photodetector based on a prepared n-Ga2O3 / p-GaN heterojunction, a cross-group amplifier, a single-chip microcontroller chip, a level conversion module, a Wi-Fi module, and mobile terminal software. A program written in C language converts electrical signals into digital signals for output.

[0017] Beneficial effects: Compared with the existing technology, the present invention has the following significant effects: an effective heterojunction structure is constructed by a single sheet-like n-Ga2O3 micron wire and a p-GaN substrate, and a single-layer graphene electrode is used as the top transparent electrode. The good conductivity and extremely high transmittance in the solar-blind band are utilized to greatly improve the device's light absorption ability in the ultraviolet band. The device has good carrier transport efficiency and an efficient electron transport channel, achieving high responsiveness, high specific detectivity, and high external quantum efficiency at a 0V bias. At the same time, thanks to the anisotropy of the n-Ga2O3 micron wire, the device has the characteristics of polarization sensitivity in the solar-blind band and can maintain a high extinction ratio, realizing the application of the device in polarization-encrypted communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the device of the present invention.

[0019] Figure 2 The IV characteristic curves of the device of the present invention at 0V bias and different powers.

[0020] Figure 3 The IT curves of the device of the present invention at 0V bias and different powers.

[0021] Figure 4 It is the IT curve of the device of the present invention under 0V bias, equal power and different polarization angles.

[0022] Figure 5 Schematic diagram of the application of the device of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further explained and illustrated below in conjunction with embodiments and the accompanying drawings.

[0024] Embodiment 1

[0025] As Figure 1 shown, this embodiment discloses a polarization-sensitive narrowband solar-blind self-powered photodetector, including: sheet-like n-Ga2O3 micro-wires 1, p-GaN substrate 2, PET (polyethylene terephthalate) 3, single-layer graphene electrode 4, metal Ni / Au alloy electrode 5; the length of the sheet-like n-Ga2O3 micro-wires 1 is 0.5 - 0.6 cm, the diameter is 15 μm, the electron concentration is 10 18 / cm 3 and the carrier mobility is 90 cm 2 / V·s; a metal Ni / Au alloy electrode 5 with a thickness of 100 nm is evaporated on one end of the short side of the p-GaN substrate 2, the upper layer Au thickness in this electrode 5 is 50 nm, and the lower layer Ni thickness is 50 nm; there is a 15-μm channel between two PETs 3, and the two PETs 3 are symmetrically pasted on the part of the p-GaN substrate 2 where the metal Ni / Au alloy electrode 5 is evaporated without the electrode, the thickness of this p-GaN substrate 2 is 350 μm, the electron mobility is 2000 cm 2 / V·s, the size is 1 cm × 0.5 cm, the thickness of the single-layer graphene electrode 4 is 0.35 nm, the surface resistivity is 400 - 600 Ω / square, and the size is 0.4 cm × 0.4 cm; a single sheet-like n-Ga2O3 micro-wire 1 is located in the channel between two PETs 3, and the central part of the single-layer graphene electrode 4 is in close contact with the single sheet-like n-Ga2O3 micro-wire 1 to form a Schottky junction.

[0026] Embodiment 2

[0027] This embodiment provides a polarization-sensitive narrowband solar-blind self-powered photodetector and its preparation method, including the following steps:

[0028] The first step: First, put the p-GaN substrate 2 into a clean beaker, add trichloroethylene to completely submerge it, use an ultrasonic cleaner to clean the p-GaN substrate 2 for 15 min, after the cleaning is over, then use acetone, ethanol, and deionized water to clean it in an ultrasonic cleaner for 15 min respectively, then use high-purity nitrogen to clean the residual liquid on the surface of the substrate, and finally dry the cleaned p-GaN substrate 2 in an 80°C constant-temperature drying oven to ensure that the surface of the substrate is dry, clean, and free of other impurities.

[0029] Step 2: First, use a mask to block the part of the cleaned p-GaN substrate 2 that does not need to be evaporated with an electrode. Use electron beam evaporation to evaporate a layer of metal Ni film on the surface of the p-GaN substrate 2 at a deposition rate of 8 to 10 pm / s and a thickness of 50 nm. After replacing the target, continue to multiply the metal Au film on the surface of the deposited metal Ni film at a deposition rate of 8 to 10 pm / s and a thickness of 50 nm. Then, a uniform metal Ni / Au alloy electrode 5 with a thickness of 100 nm is plated on the surface of the exposed part of the p-GaN substrate 2. Remove the mask and anneal at 500°C in a tube furnace for 10 to 15 minutes. After annealing, test the IV characteristic curve of the metal Ni / Au electrode (5). The successfully evaporated metal Ni / Au alloy electrode 5 serves as an anode to form an ohmic contact with the p-GaN substrate 2.

[0030] Step 3: Cut out two pieces of PET3 with a size of 0.4 cm × 0.3 cm and a thickness of 4 μm, transfer them to the p-GaN substrate 2 under a 5X optical microscope and stick them together, leaving a 15 μm trench between the two pieces of PET3.

[0031] Step 4: Under a 5X optical microscope, transfer the sheet-like n-Ga2O3 micron wire 1 to the channel position left by PET3 and place it on top of the p-GaN substrate 2. Apply slight pressure to make the n-Ga2O3 micron wire 1 and the p-GaN substrate 2 close together to ensure that the two form an n-Ga2O3 / p-GaN heterojunction structure; finally, cut a piece of In particle with an area of 1 / 5 of the area of the metal Ni / Au alloy electrode 5 and press it on the center position of the evaporated metal Ni / Au alloy electrode 5 as a protective electrode.

[0032] Step 5: Cut the copper-based graphene film to a size of 0.4 cm x 0.4 cm and apply stress to flatten it. Once flattened, spin the film at 400 rpm for 10 seconds, then increase the speed to 1500 rpm and maintain for 20 seconds. Then, spin-coat PMMA onto the surface, ensuring that it is evenly coated on the surface of the single-layer graphene film. After spin-coating, dry and cure the film in a 100°C oven to ensure close contact between the PMMA film and the single-layer graphene film. Then, prepare an FeCl₃ solution in a beaker. Use tweezers to evenly immerse the sample prepared in the previous step, copper-side down, in the FeCl₃ solution. Clean the copper substrate on one side of the graphene film using a displacement reaction. After soaking for 5 minutes, remove the sample with tweezers and rinse it in a beaker of deionized water. Repeat this process three times to completely remove the copper substrate and dilute the remaining FeCl₃ solution on the sample surface, leaving only the graphene film with PMMA spin-coated on the other side. Using surface tension, the graphene film is completely flattened on the water surface, with the PMMA-coated surface facing upward. Next, remove the ultrasonically cleaned quartz wafer and steadily lift the graphene film upward from the bottom, placing it flat on the wafer surface. This completes the first transfer of the graphene film. Lift the graphene film vertically upward, ensuring it is always centered on the device and evenly adheres to the surface of the n-Ga2O3 microwires. Place the transferred device and graphene film perpendicularly, allowing any remaining water between them to slowly separate from the film under gravity. After air drying, both are placed in an oven at 80°C for 120-150 minutes to ensure a tight bond between the single-layer graphene film and the quartz wafer. Remove the wafer and allow it to cool naturally at room temperature. Then, the device was placed with the graphene film side facing up and slowly immersed in a beaker of acetone for 2 hours. The PMMA film on the surface of the graphene film was corroded with acetone. Finally, the prepared sample was placed in a fume hood to allow the acetone on the surface of the graphene film to evaporate naturally, obtaining a single-layer graphene electrode as a transparent top electrode.

[0033] Step 6: Test the polarization-sensitive narrow-band solar-blind self-driven photodetector prepared in step 5. Under self-driven conditions (0V bias), draw the IV characteristic curve and the It curve, collect the detection response wavelength, and calculate the responsivity, detection rate, and external quantum efficiency of the device. Figure 2 、 Figure 3 The following are the IV characteristic curves and It characteristic curves of the polarization-sensitive narrow-band solar-blind self-driven photodetector under different light powers. Under 0V bias and 260nm light, the light-to-dark current ratio of the device reaches four orders of magnitude, and the device has a high sensitivity when the light power is from 30.4μW / cm 2 to 6728μW / cm 2The device performance is stable and the response is fast under illumination. The calculation shows that the polarization-sensitive narrow-band solar-blind self-driven photodetector based on n-Ga2O3 / p-GaN heterojunction has a response (R) of 0.211A / W at 0V and a specific detectivity (D*) of 2.15×10 12 Jones, the external quantum efficiency (EqE*) is 96.8%. In addition, Figure 4 As mentioned above, when UV light of different polarization angles is introduced, the device exhibits polarization-sensitive properties, with an extinction ratio of 10 and good stability. In summary, the polarization-sensitive narrowband solar-blind self-driven photodetector based on the n-Ga2O3 / p-GaN heterostructure not only has good performance in the solar-blind band and can stably detect incident light of different powers in the solar-blind band, but also has polarization sensitivity in the solar-blind band, fast response capability, and excellent stability, which can realize solar-blind polarization-encrypted information transmission.

[0034] Example 3

[0035] This embodiment provides an application method of a polarization-sensitive narrow-band solar-blind self-driven photoelectric detector, specifically including:

[0036] The detector integrates a transimpedance amplifier, a single-chip microcontroller, a level conversion module, and a WiFi module to form a complete ultraviolet signal processing and transmission system. A 260nm wavelength light beam passes through a polarizer and a rotating half-wave plate to generate a solar-blind ultraviolet light signal. This signal is converted into an electrical signal using the polarization-sensitive narrowband solar-blind self-driven photodetector. After amplification by a transimpedance amplifier, the signal is acquired. The single-chip microcontroller performs analog-to-digital conversion and polarization angle decryption using an algorithm written in C language. The signal level is then adjusted by the level conversion module. Finally, the WiFi module wirelessly transmits the data to a mobile terminal software, displaying light intensity, polarization status, and environmental warning information in real time. This enables intelligent sensing, encrypted communication, and remote monitoring of ultraviolet solar-blind band optical signals.

Claims

1. A polarization-sensitive narrow-band solar-blind self-driven photoelectric detector and its preparation method, characterized in that: include: p-GaN substrate (2); n-Ga2O3 micron wire (1), forming a heterojunction with the p-GaN substrate (2); Two PET substrates (3) are symmetrically arranged on the surface of the p-GaN substrate (2), and a channel for accommodating the n-Ga2O3 micron wire (1) is formed between the two substrates; A metal Ni / Au alloy electrode (5) is arranged on the edge of the p-GaN substrate (2); A graphene electrode (4) is covered on the surface of the n-Ga2O3 micron wire (1) as a transparent top electrode.

2. The polarization-sensitive narrow-band solar-blind self-driven photoelectric detector according to claim 1, characterized in that: The p-GaN substrate (2) has a thickness of 350 μm, a size of 1 cm×0.5 cm, and an electron mobility of 2000 cm 2 / V·s; the metal Ni / Au alloy electrode (5) has a thickness of 100 nm, the Ni thickness is 50 nm, and the Au thickness is 50 nm; the PET substrate (3) has a thickness of 4 μm and a specification of 0.4 cm×0.3 cm.

3. The polarization-sensitive narrow-band solar-blind self-driven photoelectric detector according to claim 1, characterized in that: The width of the channel is 15 μm, which matches the diameter of a single n-Ga2O3 micron wire (1). The single n-Ga2O3 micron wire (1) is a sheet structure with a diameter of 15 μm and a length of 0.5 to 0.6 cm.

4. The polarization-sensitive narrow-band solar-blind self-driven photoelectric detector according to claim 1, characterized in that: The graphene electrode (4) has a thickness of 0.35 nm, a surface resistivity of 400-600 Ω / □, and a size of 0.4 cm×0.4 cm.

5. A method for preparing a polarization-sensitive narrow-band solar-blind self-driven photoelectric detector according to any one of claims 1 to 4, characterized in that: The steps include: 1) cleaning the p-GaN substrate (2); 2) depositing a metal Ni / Au alloy electrode (5) on the p-GaN substrate (2) by electron beam evaporation, and performing annealing treatment; 3) symmetrically attaching PET substrates (3) to both sides of the p-GaN substrate (2), leaving a 15 μm wide trench between the two substrates for placing n-Ga2O3 micron wires (1) with the same diameter; 4) placing the n-Ga2O3 micron wire (1) in the trench so as to contact the bottom p-GaN substrate (2) to construct an n-Ga2O3 / p-GaN heterostructure; 5) The single-layer graphene electrode (4) is tightly attached to the n-Ga2O3 micron wire (1) as an n-type material electrode.

6. The preparation method according to claim 5, characterized in that Step 1) comprises: ultrasonically cleaning the p-GaN substrate (2) using trichloroethylene, acetone, ethanol and deionized water in sequence, drying with nitrogen and then baking.

7. The preparation method according to claim 5, characterized in that The step of evaporating a metal Ni / Au alloy electrode (5) on a p-GaN substrate (2) in step 2) is as follows: (S1) using a mask to cover the portion of the p-GaN substrate (2) where no electrode is to be evaporated, and using electron beam evaporation to deposit a metal Ni film on the surface of the p-GaN substrate (2) at a deposition rate of 8 to 10 pm / s and a thickness of 50 nm; (S2) replacing the target material, and continuing to deposit a metal Au film on the surface of the deposited metal Ni film at a deposition rate of 8 to 10 pm / s and a thickness of 50 nm; (S3) annealing the p-GaN substrate (2) on which the metal Ni / Au alloy electrode (5) has been evaporated at a temperature of 500°C for 10 to 15 minutes.

8. The preparation method according to claim 5, characterized in that In step 3), the thickness of the PET substrate (3) is 5 μm, which is smaller than the thickness of the sheet-like n-Ga2O3 micron wire (1).

9. The method for preparing a polarization-sensitive narrow-band solar-blind self-driven photoelectric detector according to claim 5, characterized in that: The step of constructing the n-Ga2O3 / p-GaNp-n heterostructure in step 4) includes: transferring the n-Ga2O3 micron wire (1) to the surface of the p-GaN substrate (2) exposed in the channel under a 5X optical microscope, pressing an In particle electrode on the surface of the metal Ni / Au alloy electrode (5) to construct the n-Ga2O3 / p-GaN heterostructure.

10. The method for preparing a polarization-sensitive narrow-band solar-blind self-driven photoelectric detector according to claim 5, characterized in that: Step 5) comprises: selecting a graphene with a copper base on one side and a PMMA film spin-coated on the other side, dissolving the metallic copper with a FeCl3 solution, transferring the graphene to a cleaned silicon dioxide substrate, allowing it to dry naturally, then dissolving the PMMA with acetone, transferring the graphene to the device, and finally heating the device in an oven with the oven temperature set to 60° C. and the curing time set to 120 to 150 minutes, so that the graphene is tightly attached to the upper end of the n-Ga2O3 micron wire (1) as a top transparent electrode and does not directly contact the bottom electrode.

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