A multi-wavelength surface plasmon hot electron photodetector and a preparation method and application thereof

Abstract

The present application relates to a kind of multi-wavelength surface plasmon hot electron photodetector and its preparation method and application, its structure includes substrate, two-dimensional material layer, vanadium dioxide micro-nano structure, graphene layer and top driving electrode.The detector realized by the present application not only has the characteristics such as wide spectrum, real-time tuning, room temperature operation and wavelength selectivity, and the detection performance is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detection, and specifically relates to a multi-wavelength surface plasmon thermal electron photodetector, its preparation method, and its application. Background Technology

[0002] Infrared detection technology is a crucial core technology in the military field. As this technology matures, low-cost infrared detectors are gradually being applied to civilian sectors such as security, medicine, and commerce. Infrared detectors can provide stable observations in harsh weather conditions and have significant application prospects in meteorological satellites, aerospace, security systems, and autonomous driving technologies. They are core components related to my country's cutting-edge technologies and the well-being of its people. With the increasing demand for infrared detectors, the requirements for infrared detection methods and performance are also gradually increasing. Traditional infrared detection devices have reached a point where further improvements in responsivity, response rate, and detection wavelength are difficult, and they also suffer from problems such as the need for cryogenic cooling, large size making integration difficult, and high cost. Therefore, it is essential to develop infrared detectors with higher responsivity, faster response rates, and wide-spectrum multi-wavelength detection using new principles and technologies.

[0003] Two-dimensional (2D) materials are ultrathin materials with a thickness of only one atomic layer, possessing unique optical and electrical properties and promising applications in electronics and optoelectronics. 2D materials not only exhibit high mobility, but their ultrathin thickness also allows for easy modulation via electrostatic gate voltage, thus suppressing dark noise. Furthermore, they offer advantages such as good compatibility and ease of integration into chips, making them ideal active layer materials for high-sensitivity photodetectors. However, the ultrathin nature of 2D materials limits their light absorption capacity, and the detection wavelength range of 2D material detectors, typically based on photoconductivity or photovoltaic effects, is still limited by their band gap. 2D materials alone cannot meet the requirements of higher-performance infrared detectors. To address these issues, research has combined 2D materials with metallic nanostructures, utilizing the localized surface plasmon resonance enhancement effect of metallic nanostructures to improve the light absorption of 2D materials. In addition, surface plasmons can induce the transfer of hot electrons to 2D materials, overcoming the bottleneck of band gap limitation in response wavelength. However, the wavelengths of currently reported two-dimensional material / metal nanocomposite structure detectors are controlled by the size and geometry of the nanostructure, meaning that the detectors are statically designed. Once the device is fabricated, the detection performance is determined and cannot be effectively actively tuned. Furthermore, the currently reported composite structure detectors are usually in the visible to near-infrared band, and no mid-infrared detectors have been reported. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the technical problem to be solved by this invention is to provide a multi-wavelength surface plasmon thermal electron photodetector that directly modulates the surface plasmon resonance peak of vanadium dioxide micro / nano structures through voltage driving. This solves the problem of passive wavelength tuning in traditional noble metal surface plasmon detectors. When combined with two-dimensional materials, it also has the advantages of room temperature operation, band selectivity, high responsivity, and fast response speed.

[0005] The present invention provides a multi-wavelength photodetector, which comprises, from bottom to top, a substrate 1, a two-dimensional material layer 2, a vanadium dioxide micro / nano structure 4, a graphene layer 5, and a top driving electrode 6; wherein a metal source electrode 31 and a metal drain electrode 32 are respectively provided on both sides of the two-dimensional material layer.

[0006] The substrate 1 is one of silicon dioxide, sapphire, or polyethylene terephthalate flexible polymers with a thickness of 80 nm to 300 nm that is thermally grown on a heavily doped silicon substrate.

[0007] The two-dimensional material layer 2 is made of one of the following: graphene, transition metal chalcogenides (such as MoS2, MoTe2, WS2, WSe2, molybdenum diselenide MoSe2, etc.), or black phosphorus. It can be prepared by mechanical exfoliation, chemical vapor deposition, ultrasonic exfoliation, or molecular beam epitaxy. The thickness of the two-dimensional material layer 2 is 0.3-50 nm, and its length is 1-500 μm.

[0008] The vanadium dioxide micro / nanostructure 4 is made of high-purity vanadium dioxide or tungsten-doped vanadium dioxide. The vanadium dioxide micro / nanostructure 4 comprises unit structures arranged periodically. These unit structures are either isotropic or anisotropic. The unit structures are spherical, triangular, rectangular, T-shaped, rod-shaped, or butterfly-shaped, with a size of 50-500 nm. Further, the vanadium dioxide micro / nanostructure uses high-purity vanadium dioxide or tungsten-doped vanadium dioxide. The vanadium dioxide thin film can be prepared by magnetron sputtering or laser pulse deposition, and then etched into periodic structural patterns by ion beam etching. The shapes include isotropic structures such as circles or anisotropic structures such as rods and butterflies, with unit structure sizes between 50 nm and 500 nm. Alternatively, vanadium dioxide micro / nanostructures can be directly prepared using solution methods or AAO template methods.

[0009] The graphene layer 5 has a thickness of 0.3 nm and a length of 1 μm to 500 μm.

[0010] The graphene layer is a single-layer structure. Graphene not only has good conductivity, but its high light transmittance also allows the underlying two-dimensional material to interact better with light. The preparation method is to transfer the single-layer graphene grown by chemical vapor deposition onto the vanadium dioxide micro-nano structure using a PDMS dry method.

[0011] The top driving electrode 6 is made of metal material, with a thickness of 50-100 nm and a length of 100 nm to 800 nm.

[0012] The top driving electrode is made of metal materials such as gold, silver, copper, or chromium, and is used to apply Joule heating generated by current regulation to the graphene layer.

[0013] The method involves applying different currents to the graphene layer through the top driving electrode to change the Joule heating generated in the graphene layer, thereby continuously and rapidly controlling the phase transition of vanadium dioxide between the metallic and semiconductor states.

[0014] The materials of the metal source 31 and metal drain 32 depend on the two-dimensional semiconductor material used. When the two-dimensional material is an n-type semiconductor, the metal source 31 and metal drain 32 are low work function metals; when the two-dimensional material is a p-type semiconductor, the metal source 31 and metal drain 32 are high work function metals. The thickness of the metal source 31 and metal drain 32 is 50-100 nm, and the length is 50 μm to 5000 μm. The low work function metal is one of aluminum, titanium, and scandium; the high work function metal is one of gold, platinum, and nickel.

[0015] The metal source electrode 31 and the metal drain electrode 32 can be prepared by magnetron sputtering, electron beam evaporation or thermal evaporation.

[0016] The present invention provides a method for fabricating a multi-wavelength photodetector, comprising:

[0017] (1) Loading a two-dimensional material layer on the substrate surface;

[0018] (2) Metal source and drain electrodes are fabricated at both ends of the two-dimensional material layer, respectively;

[0019] (3) Vanadium dioxide micro-nano structures are formed on the surface of the two-dimensional material layer;

[0020] (4) The monolayer graphene is transferred to the vanadium dioxide micro / nano structure by PDMS dry transfer, and then the top driving electrode is formed on the monolayer graphene layer.

[0021] The present invention relates to an application of the multi-wavelength photodetector in the field of photoelectric detection.

[0022] This invention utilizes the surface plasmon effect and phase transition characteristics of vanadium dioxide micro / nanostructures to tune and enhance the detection performance of two-dimensional materials. A graphene layer electrically drives the phase transition of the vanadium dioxide micro / nanostructure, allowing for real-time reversible phase transitions between semiconductor and metallic states that can be controlled by voltage. When vanadium dioxide is in the metallic phase, unlike the static tuning of noble metals, the surface plasmon resonance peaks of vanadium dioxide can be actively and dynamically tuned with voltage, covering the visible-near-infrared-mid-infrared bands. This overcomes the bandgap limitation of two-dimensional materials, significantly extending the detection wavelength and offering advantages such as wavelength selectivity and room-temperature operation. When vanadium dioxide is in the semiconductor phase, a built-in electric field is formed through contact with the energy bands of the two-dimensional material, effectively separating photogenerated carriers and generating a huge optical gain under bias, significantly improving responsivity and quantum efficiency. By designing anisotropic vanadium dioxide nanostructures, the device also possesses polarization detection capabilities.

[0023] When electrically driven vanadium dioxide is in a metallic state, localized surface plasmon resonances occur on the surface of the vanadium dioxide micro / nanostructure under infrared light irradiation. This is not due to radiative decay excitation generating hot carriers, but rather to the transfer of these carriers to the Schottky junction between vanadium dioxide and the two-dimensional material. At energies higher than the interface Schottky barrier, a photocurrent is formed, with the transfer time on the order of picoseconds. By applying a bias voltage to the graphene through the driving electrode, a continuous real-time phase transition in vanadium dioxide is induced, modulating the resonant peak position of the plasmons. This allows the detection wavelength of the infrared photodetector to be actively and rapidly tuned in the near-infrared to mid-infrared band. When electrically driven vanadium dioxide is in a semiconductor state, by constructing a type II band contact between vanadium dioxide and the two-dimensional material, one type of carrier in vanadium dioxide is transferred to the two-dimensional material under the influence of the built-in electric field, while the other type of carrier is localized within the vanadium dioxide, acting as a local gate, thereby modulating the conductivity of the two-dimensional material. This photoinduced gate voltage effect produces a significant optical gain, improving the device's responsivity. Furthermore, by designing anisotropic vanadium dioxide micro / nano structures, the light absorption of vanadium dioxide varies under incident light with different polarization angles, thereby enabling polarized light detection.

[0024] Beneficial effects

[0025] (1) Currently, the detection wavelength range of surface plasmon-enhanced two-dimensional material detectors is the visible-near-infrared band, and they are statically designed. That is, once the surface plasmon structure is fabricated, the resonance peak cannot be directly tuned, and there are no reports of actively tunable surface plasmon thermionic photodetectors. This invention uses a vanadium dioxide micro / nano structure as a phase change material. Under electric drive, its surface plasmon resonance peak can be tuned in real time in the near-infrared-mid-infrared band. This not only breaks the limitation of the response band by the semiconductor bandgap and extends the detection band from visible light to mid-infrared, but also has multi-wavelength detection capabilities. By designing anisotropic vanadium dioxide nanostructures, the detector exhibits different light responses to linearly polarized light with different polarization angles, thereby identifying linearly polarized light with different polarization angles.

[0026] (2) Currently, most vanadium dioxide micro / nano structure optoelectronic devices tune their phase transition characteristics by changing the temperature. However, temperature-controlled phase transition response times are slow, which is not conducive to rapid photoelectric response. Furthermore, the heating device is bulky, which is not conducive to integration and chip fabrication. In this invention, graphene and an input electrode are laid on top of the phase transition metal vanadium dioxide. By adjusting the bias voltage of the input electrode, Joule heating is generated inside the graphene, which causes the vanadium dioxide to complete a phase transition (on the order of microseconds). The phase transition speed is significantly improved compared to traditional thermal control and is precisely adjustable. The excellent light transmittance of graphene effectively avoids the influence of light absorption on the two-dimensional material layer. This electrically driven method is also conducive to the integration and miniaturization of the device.

[0027] (3) By designing the band contact between vanadium dioxide and two-dimensional materials, this invention can achieve efficient charge transfer, combined with gate voltage regulation to achieve high gain, and suppress dark noise of the device. Therefore, the device can achieve ultrasensitive detection and has significantly improved wide-spectrum detection performance.

[0028] (4) When vanadium dioxide is in the metallic state, hot electrons induced by surface plasmon resonances in the vanadium dioxide micro / nano structure are injected into the active layer of the two-dimensional material, achieving broad-spectrum detection that breaks through the band gap of the two-dimensional material. The detection wavelength can be extended to the mid-infrared band and can be directly controlled by voltage, with the advantage of rapid response. When vanadium dioxide is in the semiconductor state, high-gain photoelectric detection is achieved through charge transfer mechanism under the influence of the built-in electric field of vanadium dioxide and the two-dimensional material, with the advantages of high responsivity and quantum efficiency. Compared with some existing two-dimensional material photodetectors, the detector realized by this invention not only significantly improves the detection performance, but also has the characteristics of broad spectrum, real-time tuning, room temperature operation, and wavelength selectivity. Attached Figure Description

[0029] Figure 1 This is a front view of a broadband photodetector based on electrically driven vanadium dioxide dynamic control of two-dimensional materials.

[0030] Figure 2 (a) is a top view of an isotropic vanadium dioxide micro / nanostructure, and (b) is a top view of an anisotropic vanadium dioxide micro / nanostructure.

[0031] Figure 3 The simulation results are for the tuning of the plasmonic resonance peak during the vanadium dioxide phase transition process.

[0032] Figure 4 This is a schematic diagram of the band structure of plasmonic-induced hot electron transfer at the interface between vanadium dioxide and two-dimensional materials.

[0033] Figure 5 The results are simulation results of polarized light absorption of anisotropic vanadium dioxide micro / nano structures. Detailed Implementation

[0034] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0035] Example 1

[0036] like Figure 1 As shown, based on a multi-wavelength surface plasmon thermal electron photodetector, the detector structure includes a substrate 1, a two-dimensional material layer 2 on the substrate surface, a metal source electrode 31 and a metal drain electrode 32 on both sides of the two-dimensional material layer, and a vanadium dioxide micro-nano structure 4, a graphene layer 5 and a top driving electrode 6 on the top of the two-dimensional material layer.

[0037] Preparation methods include:

[0038] The silicon wafer with a 300nm oxide layer was ultrasonically cleaned sequentially with acetone and isopropanol for 15 minutes, and then dried with nitrogen.

[0039] Two-dimensional molybdenum diselenide material layers were prepared by mechanical exfoliation. The molybdenum disulfide crystal material was repeatedly peeled off using 3M tape and then transferred to a cleaned silicon wafer. Single-crystal few-layer molybdenum diselenide material was selected using an optical microscope.

[0040] The metal source and metal drain were patterned on both ends of the molybdenum diselenide material using ultraviolet photolithography with a channel width of 5 μm. Then, 5 nm chromium and 70 nm gold were prepared by electron beam evaporation, with chromium serving as an adhesion layer. After that, the excess photoresist was removed by acetone stripping. Finally, the electrode was annealed in a nitrogen environment for 2 hours to reduce the contact resistance between the electrode and the molybdenum disulfide.

[0041] The plasmon layer is a spherical nanostructure composed of phase-change metal vanadium dioxide, such as... Figure 2As shown in Figure a, vanadium dioxide particles with a particle size of 100 nm were prepared by hydrothermal method and spin-coated onto the surface of a molybdenum diselenide device.

[0042] A single layer of graphene was transferred onto vanadium dioxide nanoparticles via PDMS, and a 50 nm thick driving top electrode was fabricated on the graphene using electron beam lithography. The material was copper.

[0043] When no current is applied, vanadium dioxide is in a semiconductor state. In this state, the electron-hole pairs generated by photoexcitation of vanadium dioxide are effectively separated under the influence of the built-in electric field formed with selenium disulfide. Furthermore, the holes localized in vanadium dioxide act as an additional gate voltage to modulate the conductivity of molybdenum disulfide, causing a lateral shift in its threshold voltage. The lower the incident light power, the greater the responsivity; during operation, the responsivity can reach 10. 4 The A / W ratio indicates that the device can detect near-infrared light with high sensitivity. Applying a 200mA current to the graphene through the top electrode causes vanadium dioxide to transition from a semiconductor to a metallic state. The electrically driven phase transition response time is approximately 65ms, and the recovery time after stopping the applied current is 245ms. Due to the localized surface plasmon resonance effect, the resonance peak of vanadium dioxide before and after the phase transition from semiconductor to metallic state redshifts from 900nm to 1200nm. Figure 3 As shown, localized surface plasmon resonance generates hot electrons through nonradiative transitions, which then cross the Schottky barrier and inject into molybdenum disulfide, thereby enabling multi-wavelength infrared detection that breaks through the molybdenum disulfide bandgap. Figure 4 As shown, and because the generation and injection time of hot electrons is on the sub-picosecond scale, the response speed of the surface plasmon hot electron photodetector based on vanadium dioxide nanoparticles can be improved by more than three orders of magnitude compared with a single two-dimensional material photodetector.

[0044] Example 2

[0045] Based on a multi-wavelength surface plasmon thermal electron photodetector, the detector structure includes a substrate 1, a two-dimensional material layer 2 on the substrate surface, a metal source electrode 31 and a metal drain electrode 32 on both sides of the two-dimensional material layer, and a vanadium dioxide micro-nano structure 4, a graphene layer 5 and a top driving electrode 6 on the top of the two-dimensional material layer.

[0046] Preparation methods include:

[0047] The silicon wafer with a 300nm oxide layer was ultrasonically cleaned sequentially with acetone and isopropanol for 15 minutes, and then dried with nitrogen.

[0048] Two-dimensional molybdenum disulfide material layers are prepared by chemical vapor deposition, and then the molybdenum disulfide thin film is etched into micron-scale patterns by ultraviolet lithography and oxygen plasma etching.

[0049] The metal source and metal drain were patterned on both ends of the molybdenum disulfide material using ultraviolet photolithography with a channel width of 5 μm. Then, 5 nm chromium and 70 nm gold were prepared by electron beam evaporation, with chromium serving as an adhesion layer. The excess photoresist was then removed by acetone stripping. Finally, the electrode was annealed in a nitrogen atmosphere for 2 hours to reduce the contact resistance between the electrode and the molybdenum disulfide.

[0050] Plasmon layers are anisotropic micro / nano structures composed of phase-change metal vanadium dioxide, such as... Figure 2 As shown in (b), a 100 nm thick vanadium dioxide film was prepared by magnetron sputtering, and then vanadium dioxide was processed into anisotropic periodic micro-nano structures by combining electron beam lithography and ion beam etching.

[0051] A single layer of graphene was transferred onto vanadium dioxide nanoparticles via PDMS, and a 50 nm thick driving top electrode was fabricated on the graphene using electron beam lithography. The material was copper.

[0052] like Figure 5 As shown, the anisotropic vanadium dioxide nanostructure enables the detector to exhibit different optical responses to linearly polarized light with different polarization angles (0°, 45° and 90°), thereby enabling the identification of linearly polarized light with different polarization angles.

Claims

1. A multi-wavelength photodetector, characterized in that, The detector consists of a substrate (1), a two-dimensional material layer (2), a vanadium dioxide micro / nano structure (4), a graphene layer (5), and a top driving electrode (6) from bottom to top. The two-dimensional material layer is provided with a metal source electrode (31) and a metal drain electrode (32) on both sides. By applying different currents to the graphene layer through the top driving electrode, the Joule heating generated in the graphene layer is changed, thereby regulating the phase transition of vanadium dioxide between the metallic and semiconductor states.

2. The multi-wavelength photodetector according to claim 1, characterized in that, The substrate (1) is one of silicon dioxide, sapphire, or polyethylene terephthalate with a thickness of 80 nm to 300 nm that is thermally grown on a heavily doped silicon substrate.

3. The multi-wavelength photodetector according to claim 1, characterized in that, The material of the two-dimensional material layer (2) is one of graphene, transition metal chalcogenide, and black phosphorus; the thickness of the two-dimensional material layer (2) is 0.3-50nm and the length is 1-500μm.

4. The multi-wavelength photodetector according to claim 1, characterized in that, The vanadium dioxide micro-nano structure (4) is made of vanadium dioxide or tungsten-doped vanadium dioxide. The vanadium dioxide micro-nano structure (4) has a unit structure, which is arranged periodically. The unit structure is one of spherical, triangular, rectangular, T-shaped, rod-shaped, or butterfly-shaped, and the unit structure size is 50-500nm.

5. The multi-wavelength photodetector according to claim 1, characterized in that, The graphene layer (5) has a thickness of 0.3 nm and a length of 1 μm to 500 μm.

6. The multi-wavelength photodetector according to claim 1, characterized in that, The top driving electrode (6) is a metal material, which is one or more of gold, silver, copper and chromium; the thickness of the top driving electrode (6) is 50-100 nm and the length is 100 nm to 800 nm.

7. The multi-wavelength photodetector according to claim 1, characterized in that, The materials of the metal source (31) and metal drain (32) depend on the two-dimensional semiconductor material used. When the two-dimensional material is an n-type semiconductor, the metal source (31) and metal drain (32) are low work function metals; when the two-dimensional material is a p-type semiconductor, the metal source (31) and metal drain (32) are high work function metals. The thickness of the metal source (31) and metal drain (32) is 50-100 nm and the length is 50 μm~5000 μm. The low work function metal is one of aluminum, titanium, and scandium; the high work function metal is one of gold, platinum, and nickel.

8. A method for fabricating a multi-wavelength photodetector according to any one of claims 1-7, comprising: (1) Loading a two-dimensional material layer on the substrate surface; (2) Metal source and drain electrodes are fabricated at both ends of the two-dimensional material layer, respectively; (3) Vanadium dioxide micro / nano structures are formed on the surface of the two-dimensional material layer; (4) The monolayer graphene is transferred to the vanadium dioxide micro / nano structure by PDMS dry transfer, and then the top driving electrode is formed on the monolayer graphene layer.

9. An application of the multi-wavelength photodetector of claim 1 in the field of photoelectric detection.

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