Self-driven ultraviolet detector based on MXene / 4H-SiC Schottky junction and preparation method and use method thereof

Abstract

The invention discloses a novel self-driven ultraviolet photoelectric detector of a Schottky junction and a preparation method and a use method of the novel self-driven ultraviolet photoelectric detector. The invention provides an asymmetric structure. A p-type 4H-SiC substrate layer and an MXene nanosheet film layer prepared by a minimum strength layer stripping method form a Schottky junction. A Ti / Au metal electrode layer is arranged on the 4H-SiC substrate layer; an Au metal electrode layer is arranged on the MXene thin film layer; and an insulating layer is arranged between the 4H-SiC substrate layer and the Au metal electrode layer. The MXene thin film layer has excellent electronic conduction and hydrophilic characteristics, and ultraviolet light can effectively penetrate through the MXene thin film layer to reach the response layer, so that the photoelectric conversion efficiency of the ultraviolet detector is remarkably improved. The 4H-SiC substrate layer provides an ideal working environment for ultraviolet photoelectric detection by virtue of excellent high-temperature stability and wide forbidden band characteristics, and is particularly suitable for efficient detection of ultraviolet light.

Description

Technical Field

[0001] The present invention belongs to the field of ultraviolet photodetectors, and particularly relates to a self-driven ultraviolet photodetector based on an MXene / 4H-SiC Schottky junction, a preparation method thereof, and a usage method thereof. Background Art

[0002] 4H-SiC is a semiconductor material with a wide bandgap and excellent thermal stability, and is widely used in high-power, high-temperature, and high-frequency electronic ultraviolet detectors. Its excellent ultraviolet response characteristics and low dark current make it an ideal material for ultraviolet photodetectors. However, traditional 4H-SiC ultraviolet photodetectors based on p-n junctions generally face challenges such as slow response speed, low working efficiency, and difficulty in stable operation. Two-dimensional material MXene has gradually become a potential candidate material for a new generation of ultraviolet photodetectors due to its unique electronic structure, excellent conductivity, and good optical properties. Therefore, by adopting a Schottky structure with 4H-SiC as the substrate and combining the advantages of MXene materials to optimize the interface properties and electronic structure, the performance of ultraviolet detectors can be effectively improved.

[0003] Although the MXene / 4H-SiC Schottky junction self-driven ultraviolet photodetector has broad application prospects, the current related research is still in its infancy. Especially in aspects such as the preparation process, performance optimization, and long-term stability of ultraviolet detectors, there is still much room for improvement. Existing research mainly focuses on the single characteristics of materials, which severely limits the detection performance of devices.

[0004] Therefore, there is an urgent need for a higher-performance and more stable MXene / 4H-SiC Schottky junction self-driven ultraviolet photodetector. Summary of the Invention

[0005] To solve the problems that the performance and stability of ultraviolet photodetectors in the prior art need to be improved, the present invention constructs a self-driven ultraviolet photodetector with strong performance and high stability through an innovative preparation process and interface engineering.

[0006] The technical solution disclosed by the present invention is a self-driven ultraviolet photodetector based on an MXene / 4H-SiC Schottky junction, comprising:

[0007] A 4H-SiC substrate;

[0008] An MXene / 4H-SiC Schottky junction response layer, located on the 4H-SiC substrate, comprising an insulating layer and an MXene thin film, and the insulating layer is located between the 4H-SiC substrate and the MXene thin film;

[0009] A Ti / Au electrode, located on the 4H-SiC substrate;

[0010] Au electrode, located on the MXene thin film.

[0011] Furthermore, the detector structure is an asymmetric Schottky junction.

[0012] Furthermore, the contact formed by the Ti / Au electrode and the 4H-SiC substrate is an ohmic contact; the contact formed by the MXene thin film and the 4H-SiC substrate is a Schottky contact; the contact formed by the Au electrode and the MXene thin film is an ohmic contact.

[0013] The present invention also discloses a preparation method of a self-powered ultraviolet photodetector based on an MXene / 4H-SiC Schottky junction, including:

[0014] (1) Cleaning the substrate material to remove contaminants on the substrate surface;

[0015] (2) Depositing a Ti thin film and an Au thin film on one side region of the 4H-SiC substrate by electron beam evaporation to form a Ti / Au electrode;

[0016] (3) Using electron beam evaporation to deposit an insulating layer on the other side region of the 4H-SiC substrate; chemically etching the Al layer in the Ti3AlC2 material with a LiF and HCl solution to prepare an MXene nanosheet solution, and uniformly coating the MXene solution on the surface of the 4H-SiC substrate and the insulating layer after hydrophilic treatment by the drop coating method;

[0017] (4) Depositing an Au thin film on the surface of the MXene thin film on the insulating layer by electron beam evaporation to form an Au electrode.

[0018] Furthermore, the substrate adopts an epitaxial growth technique to obtain the 4H-SiC substrate by epitaxially growing a layer of p-type 4H-SiC on an n-type 4H-SiC material.

[0019] Furthermore, the cleaning of the substrate material includes ultrasonic cleaning with acetone, alcohol, and deionized water in sequence, and drying with nitrogen after cleaning.

[0020] Furthermore, the thickness of the Au thin film in the Ti / Au electrode is the same as that of the Au thin film in the Au electrode.

[0021] The present invention also discloses a ranging device for a self-powered ultraviolet photodetector based on an MXene / 4H-SiC Schottky junction, connecting the self-powered ultraviolet photodetector to an external system through an interface circuit, and the external system includes:

[0022] An ultraviolet light source for sending ultraviolet light signals;

[0023] A signal modulation unit, configured to receive the signal output from the self-powered ultraviolet photodetector and perform signal modulation;

[0024] A data processing unit, configured to use a suitable algorithm to process the data obtained by the signal modulation unit in combination with actual needs and output the processing result.

[0025] Beneficial effects: The present invention combines MXene material with 4H-SiC, and compared with traditional ultraviolet detectors, it has the following remarkable advantages:

[0026] Excellent detection performance. The present invention uses MXene material and p-type 4H-SiC to form a Schottky junction. MXene has high conductivity and good light transmittance, which can effectively enhance the response to ultraviolet light, improve the photoelectric conversion efficiency and light response performance of the ultraviolet detector.

[0027] Good stability. The present invention uses p-type 4H-SiC as the substrate. 4H-SiC has good thermal stability and low dark current, ensuring the long-term stable operation of the ultraviolet detector.

[0028] Self-powered characteristic. The ultraviolet detector prepared by the present invention benefits from the prepared MXene / 4H-SiC Schottky junction. The built-in electric field formed at the junction interface enables the detector to achieve self-powered operation through light illumination without bias voltage, which makes the detector have the characteristics of low power consumption and high sensitivity and is suitable for practical applications in portable devices. Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the self-powered ultraviolet photodetector of the present invention;

[0030] Figure 2 It is the I-V characteristic curve of the self-powered ultraviolet photodetector of the present invention in the dark field;

[0031] Figure 3 It is the I-V characteristic curve of the self-powered ultraviolet photodetector of the present invention under different 320nm light illuminations;

[0032] Figure 4 It is a schematic diagram of the responsivity performance index of the self-powered ultraviolet photodetector of the present invention;

[0033] Figure 5 It is a test diagram of the response rate of the self-powered ultraviolet photodetector of the present invention under a 320nm pulsed laser;

[0034] Figure 6 It is a long-period stability on / off test diagram of the self-powered ultraviolet photodetector of the present invention. Detailed Embodiments

[0035] The present invention will be further clarified below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, those skilled in the art will fall within the scope defined by the appended claims of this application for various equivalent modifications of the present invention.

[0036] In a first aspect, the present invention provides a self-powered ultraviolet photodetector based on the MXene and 4H-SiC Schottky structure. By using the excellent characteristics of MXene material and 4H-SiC semiconductor material, and through reasonable design of the Schottky contact, the response speed, photoelectric conversion efficiency, stability and long-term reliability of the ultraviolet photodetector are improved. Mxene is a two-dimensional transition metal carbide and nitride material with high conductivity and optical transparency, having high conductivity, excellent hydrophilicity and good electromagnetic shielding performance. The high ion migration rate of Mxene enables it to have wide applications in fields such as supercapacitors, lithium / sodium ion batteries, and electrocatalysis.

[0037] As Figure 1 shown in the figure is an ultraviolet photodetector according to an embodiment of the present invention, including: a 4H-SiC substrate (1), a Ti / Au electrode, an insulating layer (4), an MXene thin film (5), and an Au electrode (6), and the Ti / Au electrode is composed of a Ti part (2) and an Au part (3).

[0038] The 4H-SiC substrate (1) uses a p-type 4H-SiC single crystal substrate semiconductor material, which has excellent optoelectronic properties. The bandgap of 4H-SiC is 3.26 eV, which is suitable for ultraviolet light detection, and has strong thermal stability and radiation resistance, and can maintain stable operation under harsh environmental conditions. The substrate adopts an epitaxial growth technique, and by epitaxially growing a layer of p-type 4H-SiC on an n-type 4H-SiC substrate, the substrate has good optoelectronic characteristics and stability.

[0039] On one side of the 4H-SiC substrate (1), a 20-nm Ti thin film and a 60-nm Au thin film are deposited by electron beam evaporation to construct a Ti / Au electrode that forms an ohmic contact with 4H-SiC. This structure can ensure the stable flow of current and reduce the contact resistance of the ultraviolet detector.

[0040] To prevent short circuit, an insulating layer (4) with a thickness of 100 nm is used to ensure effective isolation between the electrode and the substrate. This layer can also play a role in stabilizing the performance of the ultraviolet detector. Preferably, MgO is used as the insulating layer material in this embodiment.

[0041] According to the characteristics of the MXene material, the work function of MXene is higher than that of 4H-SiC, and electrons transfer from 4H-SiC to MXene. Therefore, a Schottky contact is formed between the MXene thin film (5) and the 4H-SiC substrate (1). At the same time, the MXene material has excellent transparency and conductivity, which can effectively enhance the response to ultraviolet light and improve the charge collection efficiency, thereby increasing the response speed and sensitivity of the ultraviolet detector.

[0042] On the surface of the MXene thin film (5) above the MgO insulating layer (4), a 60-nm-thick thin film Au electrode (6) is deposited by electron beam evaporation. The Au electrode (6) forms an ohmic contact with the MXene thin film (5) to ensure the efficient collection and output of photocurrent.

[0043] In a second aspect, the present invention also discloses a preparation method of the self-powered ultraviolet photodetector as described above, including the following steps:

[0044] Step (1) Cleaning treatment of the 4H-SiC substrate: The p-type 4H-SiC single crystal substrate is ultrasonically cleaned successively with acetone, alcohol, acetone, alcohol, and deionized water. The ultrasonic cleaning time is 10 minutes each to ensure the removal of contaminants on the substrate surface. After cleaning, the substrate surface is dried with nitrogen to ensure a clean surface.

[0045] Step (2) Deposition of the Ti / Au electrode: In a region on one side of the 4H-SiC substrate, a 20-nm Ti thin film and a 60-nm Au thin film are deposited by electron beam evaporation to form a Ti / Au electrode, which forms an ohmic contact with the 4H-SiC substrate. The Ti electrode plays a role in improving the contact, while the Au electrode ensures good conductivity. After completing the above steps, the ultraviolet photodetector based on the MXene / 4H-SiC Schottky structure is completed. The ultraviolet detector has good optoelectronic response performance and self-powered characteristics.

[0046] Step (3) Deposition of the MgO insulating layer: Using electron beam evaporation, a 100-nm-thick MgO insulating layer is deposited in a region on the other side of the 4H-SiC substrate.

[0047] Step (4) Preparation of the MXene thin film: The Al layer in the Ti3AlC2 material is chemically etched using LiF and HCl solutions to prepare a MXene nanosheet solution. The MXene solution is uniformly coated on the surface of the ozone-treated 4H-SiC substrate and the MgO insulating layer by the drop-casting method. After coating, it is dried in a vacuum environment.

[0048] Step (5) Deposition of the Au electrode: Using electron beam evaporation, a 60-nm-thick Au electrode is deposited on the MXene thin film above the MgO insulating layer to ensure that the current flows through the MXene thin film to the external circuit.

[0049] To evaluate the performance of the ultraviolet detector of the present invention, the optoelectronic characteristics of the ultraviolet detector prepared according to the present invention were tested. The test environment was a test system with a dark room and a controllable ultraviolet light source to ensure the accuracy and repeatability of the test. The test parameters included spectral response, response time, dark current, and photocurrent at different wavelengths. All tests were carried out at a room temperature of 25 °C and an air humidity of 45%.

[0050] In this embodiment, the optoelectronic characteristics of the ultraviolet detector prepared according to the above method were tested. Specifically, the bandgap width of the p-type 4H-SiC ultraviolet detector prepared in this embodiment was 3.26 eV; the p-type 4H-SiC layer was a thin film structure with a thickness of 400 nm and a resistivity of about 0.08 Ω·cm; the thickness of the MgO insulating layer was 100 nm, the thicknesses of Ti / Au on the substrate surface were 20 nm and 60 nm respectively, the thickness of the MXene material layer was 2 μm, and the thickness of the Au thin film electrode on the surface of the MXene material layer was 60 nm.

[0051] The current-voltage (I-V) characteristic curves of the obtained ultraviolet detector under dark field and 320 nm ultraviolet light illumination are as Figure 2 、 Figure 3 shown. The experimental results show that the ultraviolet detector has ideal Schottky junction rectification characteristics and exhibits significant optical response tunability under ultraviolet light illumination with different power densities. This indicates that the ultraviolet detector has excellent optoelectronic conversion ability and is suitable for ultraviolet light detection applications.

[0052] As Figure 4 shown is the spectral response characteristic of the ultraviolet detector prepared in this embodiment. In the self-driven mode, the ultraviolet detector exhibits excellent responsivity in the ultraviolet light region, indicating that the constructed ultraviolet detector has excellent self-driven ultraviolet detection ability. The strongest responsivity is 193.25 mA / W at 320 nm, and this high responsivity further proves the competitive advantage of the detector in ultraviolet detection applications.

[0053] As Figure 5 shown are the test results of the response speed of the ultraviolet detector prepared in this embodiment. Under the illumination of 320 nm pulsed light at 50 Hz, the rise time (τ r ) of the ultraviolet detector in the unbiased mode was 3.82 ms, and the fall time (τ d ) was 4.79 ms. This response speed is excellent among similar ultraviolet detectors. It indicates that the ultraviolet detector has the ability of fast response and is suitable for ultraviolet detection applications with fast response.

[0054] In the stability test after three months, the current-time (I-T) curve of the ultraviolet detector was tested under the same conditions, and the changes in photocurrent and dark current were small. As Figure 6 shown, it indicates that the ultraviolet detector prepared by the present invention can maintain high reliability and stability during long-term operation and is suitable for long-term use in practical applications.

[0055] In a third aspect, the present invention also discloses a method for using the self-powered ultraviolet detector. The practical use of the self-powered ultraviolet detector based on the Mxene / 4H-SiC Schottky junction provided by the present invention depends on an external system. The ultraviolet detector prepared by the foregoing method of the present invention is integrated into the external system and connected to the devices of the external system through an interface circuit to achieve data acquisition, processing, and display. The external system includes:

[0056] A signal modulation unit for receiving the signal output by the self-powered ultraviolet photodetector and performing signal modulation;

[0057] A data processing unit for using a suitable algorithm to process the data obtained by the signal modulation unit in combination with actual needs and outputting a processing result.

[0058] When ultraviolet light irradiates the MXene layer of the detector, the part of the photon energy greater than the semiconductor bandgap will be absorbed, causing electrons in the valence band to transition to the conduction band and generating electron-hole pairs. The Schottky barrier formed at the MXene / 4H-SiC interface will separate these photo-generated carriers, where electrons are collected by the MXene layer and holes are collected by the 4H-SiC substrate. Since the Ti / Au electrode forms an ohmic contact with the 4H-SiC substrate, holes can be smoothly exported to the external circuit; at the same time, the Au electrode on the MgO insulating layer collects electrons through the MXene thin film and exports them, forming a current in the external circuit in the direction from 4H-SiC(1) to MXene(5).

[0059] The current conducted by the ultraviolet detector passes through the modulation unit of the external system to form a current signal that can be recognized by the computer system. The data processing unit of the external system processes the current signal and outputs a processing result in combination with the actual usage scenario.

[0060] Optionally, the external system is connected to a display unit to provide a human-computer interaction interface for real-time display of the test results.

[0061] The self-powered ultraviolet detector disclosed by the present invention has excellent detection performance, high photoelectric conversion efficiency, low power consumption, good stability, and integration ability, and can meet the requirements for miniaturization, low energy consumption, and high performance of ultraviolet detectors in ultraviolet detection applications.

Claims

1. A self-powered ultraviolet photodetector based on MXene / 4H-SiC Schottky junction, characterized in that, Comprising: 4H-SiC substrate; MXene / 4H-SiC Schottky junction response layer, located on the 4H-SiC substrate, including an insulating layer and a MXene thin film, the insulating layer being located between the 4H-SiC substrate and the MXene thin film; Ti / Au electrode, located on the 4H-SiC substrate; Au electrode, located on the MXene thin film.

2. The self-powered ultraviolet photodetector according to claim 1, wherein The detector structure is a Schottky junction.

3. The preparation method according to claim 2, wherein The contact formed by the Ti / Au electrode and the 4H-SiC substrate is an ohmic contact.

4. The preparation method according to claim 3, characterized in that, The contact formed by the MXene thin film and the 4H-SiC substrate is a Schottky contact.

5. The preparation method according to claim 4, wherein, The contact formed by the Au electrode and the MXene thin film is an ohmic contact.

6. A preparation method of a self-powered ultraviolet photodetector based on an MXene / 4H-SiC Schottky junction, characterized in that, Comprising: (1) Cleaning the substrate material to remove contaminants on the substrate surface; (2) In one side region of the 4H-SiC substrate, depositing a Ti thin film and an Au thin film by electron beam evaporation to form a Ti / Au electrode; (3) Using electron beam evaporation to deposit an insulating layer in the other side region of the 4H-SiC substrate; chemically etching the Al layer in the Ti3AlC2 material with LiF and HCl solutions to prepare a MXene nanosheet solution, and uniformly coating the MXene solution on the surface of the 4H-SiC substrate and the insulating layer after hydrophilic treatment by drop coating; (4) Using electron beam evaporation to deposit an Au thin film on the surface of the MXene thin film on the insulating layer to form an Au electrode.

7. The preparation method according to claim 6, characterized in that, The substrate is obtained by epitaxial growth technology, by epitaxially growing a layer of p-type 4H-SiC on an n-type 4H-SiC material to obtain the 4H-SiC substrate.

8. The preparation method according to claim 7, characterized in that, The cleaning of the substrate material includes ultrasonic cleaning with acetone, alcohol, and deionized water in sequence, and drying with nitrogen after cleaning.

9. The preparation method according to claim 8, wherein The thickness of the Au thin film in the Ti / Au electrode is the same as the thickness of the Au thin film in the Au electrode.

10. A method for using a self-powered ultraviolet photodetector based on an MXene / 4H-SiC Schottky junction, characterized in that, Connect the self-powered ultraviolet photodetector according to claim 1 to an external system through an interface circuit to realize data acquisition, processing, and display. The external system includes: A signal modulation unit, for receiving the signal output by the self-powered ultraviolet photodetector and performing signal modulation; A data processing unit, for using a suitable algorithm to process the data obtained by the signal modulation unit in combination with actual needs and output a processing result.

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