Photovoltaic photoelectric logic gate device of CoAl2O4-based heterojunction film and preparation method of photovoltaic photoelectric logic gate device

Abstract

The invention discloses a photovoltaic type photoelectric logic gate device of a CoAl2O4-based heterojunction film and a preparation method thereof, and aims to solve the problems that a traditional photoelectric logic gate device is limited in response wave band, needs to be driven by external bias voltage, is relatively high in energy consumption and is single in logic function. According to the photovoltaic type photoelectric logic gate device of the CoAl2O4-based heterojunction thin film, the CoAl2O4 thin film is deposited on the upper surface of the SiC substrate through pulse laser, a plurality of surface electrodes are arranged on the CoAl2O4 thin film, a bottom electrode is arranged on the lower surface of the SiC substrate, and different logic gate functions are achieved by changing different positions, irradiated by the laser, of the CoAl2O4 thin film. According to the CoAl2O4 thin film provided by the invention, the separation of photo-induced electron-hole pairs is effectively promoted by forming a CoAl2O4 / SiC structure, the recombination rate is reduced, and under the irradiation of a 266nm light source, along with the change of an illumination position, the logic gate state is switched quickly.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectric detection, and specifically relates to a CoAl2O4-based heterostructure device based on a laser pulse deposition method and a preparation method thereof, and uses the device as a photoelectric logic gate device. Background Art

[0002] In recent years, due to the continuous advancement of technologies such as big data and artificial intelligence, data volumes have increased significantly. Current electronic logic gates are limited in accuracy and computational speed. The explosive demand for large-scale data processing has sparked interest in new logic gate platforms. Compared to electronic logic gates, optoelectronic logic gates offer lower device integration, lower power consumption, and faster computational speeds, attracting significant attention in fields such as visible light communications, lidar, and artificial intelligence optical computing. Traditional optoelectronic logic gates typically rely on polarization control or multiple optical-electrical inputs to achieve multi-state logic, resulting in complex processes and limited response bands. Furthermore, most current devices typically require an external bias voltage to drive, resulting in high energy consumption. Their limited logic functionality makes them difficult to cascade directly using optical signals. Therefore, there is an urgent need for optoelectronic logic gates with a simple structure, fast response, and the ability to perform multiple logical operations.

[0003] The lateral photovoltaic effect is a special surface photovoltaic effect phenomenon. Its most notable feature is that the photoelectric response signal output by the device changes as the light spot moves across the semiconductor surface. Current semiconductor heterojunction photodetectors based on the lateral photovoltaic effect have the advantages of simple structure, high detection sensitivity, and no need for external power supply. They can also regulate the separation and transmission of photogenerated carriers through band structure, further improving photoelectric performance. Furthermore, due to the high dependence of the signal intensity of such detectors on the position of illumination, multiple logic gate structures can be realized by processing the device surface when the laser illuminates different positions on the surface.

[0004] SiC materials have characteristics such as a wide bandgap, high temperature resistance, radiation resistance, high breakdown electric field, and low dielectric constant. Spinel oxides, with their complex lattice structure and distribution of variable-valence ions, are widely used in spin logic devices, electrochemical energy materials, and semiconductor materials. Among them, CoAl2O4 spinel oxide films exhibit excellent physical and chemical stability in complex environments. Their p-type conduction at room temperature and epitaxial growth on substrates with larger lattice mismatches make them ideal candidates for designing heterojunction optoelectronic devices. Combining CoAl2O4 with SiC to form a heterojunction can effectively create a built-in electric field, maximizing the advantages of spinel oxide materials in optoelectronic devices and facilitating the preparation of novel optoelectronic logic gate devices with high sensitivity and ultrafast response speeds. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of traditional photoelectric logic gate devices, such as complex process, limited response band, requirement for external bias to drive, high energy consumption and single logical function, and to propose a photovoltaic photoelectric logic gate device of CoAl2O4-based heterojunction thin film and a preparation method thereof. The method has the advantages of simple preparation process, convenient operation, low cost and easy control of experimental conditions. The device has the characteristics of self-power supply and realizes multiple photoelectric logic gate structures by changing the light position at an ultra-fast response speed, and is suitable for the field of photoelectric detection.

[0006] The photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film of the present invention includes a SiC substrate, a CoAl2O4 thin film, multiple surface electrodes and a bottom electrode. A CoAl2O4 thin film with a thickness of 10 to 60 nm is deposited on the upper surface of the SiC substrate using a pulsed laser. Multiple surface electrodes are arranged on the CoAl2O4 film. A bottom electrode is arranged on the lower surface of the SiC substrate. Different logic gate functions are achieved by changing the position of the laser irradiation on the CoAl2O4 film.

[0007] The present invention uses the lateral photovoltaic between different surface electrodes as the input value and the longitudinal photovoltaic between the surface electrode and the bottom electrode as the output value. When the laser is irradiated at different positions of the CoAl2O4 film, a variety of photoelectric logic gate functions can be realized.

[0008] The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film of the present invention is implemented by the following steps: 1. Mix Co2O3 powder and Al2O3 powder, press into tablets through a mold, and then sinter at 900~1100℃ to obtain CoAl2O4 target; 2. Placing the SiC substrate in acetone, anhydrous ethanol and deionized water in turn for ultrasonic cleaning to obtain a cleaned SiC substrate; 3. Place the cleaned SiC substrate on a tray in the chamber. After the chamber is evacuated and oxygen is introduced, the SiC substrate is heated. An excimer laser is used to irradiate the CoAl2O4 target. The pulsed laser output is controlled to have an energy of 200mJ and a repetition frequency of 1-5Hz to perform pulsed laser deposition of a thin film. After holding the temperature, the film is naturally cooled to obtain a CoAl2O4 / SiC heterojunction material. 4. A plurality of surface electrodes are provided on the CoAl2O4 thin film of the CoAl2O4 / SiC heterojunction material, and a bottom electrode is provided on the lower surface of the SiC substrate, thereby obtaining a photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film.

[0009] The application of the photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film of the present invention is as a photoelectric logic gate device.

[0010] This invention uses a wide-bandgap semiconductor, SiC, as a substrate and CoAl2O4 as a thin film material to form a semiconductor heterojunction to fabricate a photoelectric logic gate device. SiC is a wide-bandgap semiconductor material, and its detection range approaches the shortwave region and can extend into the solar-blind zone, facilitating detection in specific environments.

[0011] The photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film and the preparation method thereof of the present invention have the following beneficial effects: 1. The CoAl2O4 thin film provided by the present invention effectively promotes the separation of photogenerated electron-hole pairs by forming a CoAl2O4 / SiC structure, reduces the recombination rate, and significantly improves the photoelectric performance of the detector; 2. The photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film provided by the present invention has inexpensive and readily available raw materials, a simple process, energy conservation and emission reduction, and greatly reduces costs; 3. The photovoltaic photoelectric logic gate device based on the CoAl2O4 heterojunction thin film provided by the present invention switches the logic gate state rapidly as the illumination position changes under 266nm light source illumination, making it suitable for multiple logic gate photoelectric detection applications. 4. The photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film provided by the present invention realizes multiple photoelectric logic gates using a single device, exhibits excellent performance, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the structure of the photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film in Example 1; Figure 2 This is a graph showing the relationship between the potential difference between the surface electrode and the bottom electrode of the CoAl2O4 / SiC structure prepared in Example 1 and the change in laser power; Figure 3 This is a graph showing the relationship between the potential difference between two adjacent surface electrodes of the CoAl2O4 / SiC structure prepared in Example 1 and the change in laser power; Figure 4 This is a truth table diagram of an “AND gate” for a multiple logic gate test of a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film prepared in Example 1; Figure 5 This is a truth table diagram of an "XOR gate" for a multiple logic gate test of a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film prepared in Example 1; Figure 6 This is a truth table diagram of an "XNOR gate" for a multiple logic gate test of a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film prepared in Example 1; Figure 7This is a truth table diagram of a "NOR gate" for multiple logic gate tests of a photovoltaic photoelectric logic gate device based on a CoAl2O4-based heterojunction thin film prepared in Example 1; Figure 8 This is a test diagram of the "AND gate" results of the multiple logic gate test of the photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film prepared in Example 1; Figure 9 This is a test diagram of the "XOR gate" result of the multiple logic gate test of the photovoltaic photoelectric logic gate device based on the CoAl2O4 heterojunction thin film prepared in Example 1; Figure 10 This is a test diagram of the "XNOR gate" result of the multiple logic gate test of the photovoltaic photoelectric logic gate device based on the CoAl2O4 heterojunction thin film prepared in Example 1; Figure 11 This is a test diagram of the "NOR gate" results of the multiple logic gate test of the photovoltaic photoelectric logic gate device based on the CoAl2O4 heterojunction thin film prepared in Example 1. DETAILED DESCRIPTION

[0013] Specific embodiment 1: The preparation method of the photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film in this embodiment is implemented according to the following steps: 1. Mix Co2O3 powder and Al2O3 powder, press into tablets through a mold, and then sinter at 900~1100℃ to obtain CoAl2O4 target; 2. Placing the SiC substrate in acetone, anhydrous ethanol and deionized water in turn for ultrasonic cleaning to obtain a cleaned SiC substrate; 3. Place the cleaned SiC substrate on a tray in the chamber. After the chamber is evacuated and oxygen is introduced, the SiC substrate is heated. An excimer laser is used to irradiate the CoAl2O4 target. The pulsed laser output is controlled to have an energy of 200mJ and a repetition frequency of 1-5Hz to perform pulsed laser deposition of a thin film. After holding the temperature, the film is naturally cooled to obtain a CoAl2O4 / SiC heterojunction material. 4. A plurality of surface electrodes are provided on the CoAl2O4 thin film of the CoAl2O4 / SiC heterojunction material, and a bottom electrode is provided on the lower surface of the SiC substrate, thereby obtaining a photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film.

[0014] This CoAl2O4-based heterojunction thin film photovoltaic logic gate device utilizes the lateral photovoltaic energy generated between different surface electrodes and the longitudinal photovoltaic energy generated between the surface and bottom electrodes as the logic gate input and output. By varying the laser irradiation position, multiple optoelectronic logic gate characteristics can be achieved. This CoAl2O4 / SiC device utilizes the heterojunction's band-matching mechanism to promote the separation of photogenerated carriers, effectively improving optoelectronic performance and enabling the construction of multiple optoelectronic logic gates.

[0015] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the molar ratio of Co2O3 powder to Al2O3 powder in step 1 is 1:2.

[0016] Specific embodiment three: This embodiment differs from specific embodiments one or two in that the sintering treatment time in step one is 10 to 15 hours.

[0017] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that the SiC substrate described in step 2 is a 4H-SiC substrate.

[0018] Specific embodiment 5: This embodiment differs from any one of specific embodiments 1 to 4 in that the oxygen is introduced in step 3 to control the pressure to be 0.01-20 Pa.

[0019] Specific embodiment 6: This embodiment differs from any one of specific embodiments 1 to 5 in that in step 3, the temperature of the SiC substrate is raised to 600-650°C.

[0020] Specific embodiment seven: This embodiment differs from any one of specific embodiments one to six in that in step three, the pulsed laser output is controlled to have an energy of 200 mJ and a repetition frequency of 1 Hz for pulsed laser deposition of thin films.

[0021] Specific embodiment eight: This embodiment differs from any one of specific embodiments one to seven in that in step three, the film is deposited by pulse laser and then kept warm for 20 to 30 minutes.

[0022] Specific embodiment 9: The difference between this embodiment and any one of specific embodiments 1 to 8 is that the material of the surface electrode in step 4 is gold, and the bottom electrode is formed by drying silver paste.

[0023] Specific embodiment 10: In this embodiment, the application of the photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film is as a photoelectric logic gate device.

[0024] This embodiment uses a light source with a wavelength of 266nm to irradiate the CoAl2O4-based heterojunction thin film, which can be used to construct multiple photoelectric logic gates.

[0025] Example 1: The preparation method of the photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film of this embodiment is carried out according to the following steps: 1. Mix Co2O3 and Al2O3 powders in a molar ratio of 1:2, press into tablets through a mold, and then sinter at 1000℃ for 12h to obtain CoAl2O4 target; 2. The SiC substrate was sequentially placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 10 minutes each to obtain a cleaned SiC substrate; 3. Place the cleaned SiC substrate on the tray in the chamber and pump the background vacuum to 4×10 -4 Pa, with the cleaned SiC substrate as the substrate, pure oxygen was introduced to control the gas pressure to 0.1 Pa, the temperature of the SiC substrate was adjusted to 620℃, and an excimer laser was used to irradiate the CoAl2O4 target. The single pulse energy was controlled to 200mJ and the pulse frequency was 1Hz to perform pulsed laser deposition of a CoAl2O4 layer with a thickness of 15nm. After the deposition, the layer was kept in situ for 30min and finally cooled naturally to room temperature to obtain a photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film.

[0026] The SiC substrate described in step 2 of this embodiment was purchased from Tianke Heda Blue Light Semiconductor Co., Ltd., and the excimer laser described in step 3 was a KrF gas laser from Compex, Germany.

[0027] The construction process of photovoltaic photoelectric logic gate device test equipment is as follows: Figure 1 This is a schematic diagram of a photovoltaic optoelectronic logic gate device based on a CoAl2O4-based heterojunction thin film fabricated in Example 1. A laser (wavelength of 266 nm) is mounted on a stable support. A lens with a focal length of 1 cm is placed in the optical path after a beam expander, focusing the laser spot on the thin film at a point approximately 0.1 mm in diameter. Several pieces of gold are pressed onto the thin film surface as surface electrodes, and silver paste is applied to the underside of the substrate as the ground electrode. The surface electrode has a diameter of less than 0.5 mm. An electric motor controls the movement of a two-dimensional translation stage, thereby changing the illumination position.

[0028] The near-ultraviolet light-sensitive sensor prepared in Example 1, under the irradiation of a laser with a wavelength of 266 nm and a power of 1 mW, has a maximum potential difference between the surface and bottom electrodes of the CoAl2O4 / SiC structure of 422.13 mV / mm ( Figure 2 ), the potential difference between two adjacent electrodes on the surface reached a maximum of 411.37mV / mm ( Figure 3 ).

[0029] Testing method for multiple optoelectronic logic gates: A laser (wavelength of 266nm) is mounted on a stable bracket. A lens with a focal length of 1cm is placed in the optical path after a beam expander. This focuses the laser spot on a point on the film with a diameter of approximately 0.1mm. Several pieces of gold are pressed onto the film surface as surface electrodes, and silver paste is applied to the bottom surface of the substrate as a bottom electrode. The surface electrode has a diameter of less than 0.5mm. An electric motor controls the movement of a two-dimensional translation stage, thereby changing the illumination position. An oscilloscope, model Tektronix DP05054, was used to observe in real time the potential differences between the surface electrodes a and b, and between the surface electrodes a and c of the CoAl2O4 / SiC structure (this was defined as input signals 1 and 2). By continuously changing the laser irradiation position on the device surface (from surface electrode a to surface electrode d), the potential difference between the surface electrode a and the bottom electrode, the potential difference between the surface electrode d and the bottom electrode, the potential difference between the surface electrode a and the surface electrode d, and the potential difference between the surface electrode b and the surface electrode d at different irradiation positions were observed in turn (this was defined as the output signal). By comparing with the truth table, it was found that the construction of multiple logic gates, including "AND gate", "XOR gate", "XNOR gate", and "NOR gate", was achieved. The structural diagram and truth table of the multiple photoelectric logic gate test are shown in the figure. Figure 4-Figure 7 and Figures 8-11 As shown, the lateral photovoltaics generated between the electrodes on different surfaces of the device and the longitudinal photovoltaics between the surface and the bottom of the device are used as the input and output of the logic gate, and the multiple photoelectric logic gate characteristics of the device are observed by changing the laser irradiation position.

[0030] The present invention compresses and sinters a mixed powder of Co2O3 and Al2O3 in a specific ratio to obtain a CoAl2O4 target. Using SiC as a substrate, a CoAl2O4 thin film is deposited on the substrate surface via pulsed laser deposition. After deposition, the device is insitu heat-insulated and then naturally cooled to room temperature to obtain a CoAl2O4 / SiC heterojunction device. The lateral photovoltaics generated between electrodes on different surfaces of the device and the longitudinal photovoltaics between the device surface and bottom are used as the input and output of logic gates. The multiple photoelectric logic gate characteristics of the device are observed by varying the laser irradiation position. Tests have shown that the prepared CoAl2O4 / SiC device promotes the separation of photogenerated carriers through the band-matching mechanism of the heterojunction, thereby effectively improving photoelectric performance and having application in the construction of multiple photoelectric logic gates.

Claims

1. Photovoltaic photoelectric logic gate device based on CoAl2O4 heterojunction thin film, characterized by The photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film includes a SiC substrate, a CoAl2O4 thin film, multiple surface electrodes and a bottom electrode. A CoAl2O4 thin film with a thickness of 10 to 60 nm is deposited on the upper surface of the SiC substrate using a pulsed laser. Multiple surface electrodes are arranged on the CoAl2O4 film, and a bottom electrode is arranged on the lower surface of the SiC substrate. Different logic gate functions are achieved by changing the position of the laser irradiation on the CoAl2O4 film.

2. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 1, characterized in that The preparation method of the photovoltaic photoelectric logic gate device is implemented according to the following steps:

1. Mix Co2O3 powder and Al2O3 powder, press into tablets through a mold, and then sinter at 900~1100℃ to obtain CoAl2O4 target; 2. Placing the SiC substrate in acetone, anhydrous ethanol and deionized water in turn for ultrasonic cleaning to obtain a cleaned SiC substrate; 3. Place the cleaned SiC substrate on a tray in the chamber. After the chamber is evacuated and oxygen is introduced, the SiC substrate is heated. An excimer laser is used to irradiate the CoAl2O4 target. The pulsed laser output is controlled to have an energy of 200mJ and a repetition frequency of 1-5Hz to perform pulsed laser deposition of a thin film. After holding the temperature, the film is naturally cooled to obtain a CoAl2O4 / SiC heterojunction material.

4. A plurality of surface electrodes are provided on the CoAl2O4 thin film of the CoAl2O4 / SiC heterojunction material, and a bottom electrode is provided on the lower surface of the SiC substrate, thereby obtaining a photovoltaic photoelectric logic gate device of the CoAl2O4-based heterojunction thin film.

3. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 2, characterized in that In step 1, the molar ratio of Co2O3 powder to Al2O3 powder is 1:

2.

4. The method for preparing a photovoltaic type photoelectric logic gate device of a CoAl2O4 based heterojunction thin film according to claim 2, characterized in that The sintering treatment time in step 1 is 10 to 15 hours.

5. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 2, characterized in that The SiC substrate described in step 2 is a 4H-SiC substrate.

6. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 2, characterized in that In step 3, oxygen is introduced to control the pressure to be 0.01~20Pa.

7. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 2, characterized in that In step 3, the SiC substrate is heated to 600-650°C.

8. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 2, characterized in that In step 3, the pulsed laser output is controlled to have an energy of 200 mJ and a repetition frequency of 1 Hz to perform pulsed laser deposition of thin films.

9. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 2, characterized in that In step 3, after the pulsed laser deposition of the thin film, the film is kept in situ for 20 to 30 minutes.

10. The method for preparing a photovoltaic photoelectric logic gate device of a CoAl2O4-based heterojunction thin film according to claim 2, characterized in that In step 4, the surface electrode is made of gold, and the bottom electrode is made by drying silver paste.

Images