Highly sensitive ultrafast response uv photodetector based on two-dimensional moire superlattice
By using a two-dimensional moiré superlattice-based ultraviolet photodetector, and leveraging the Auger effect multiplication and exciton separation of torsion two-dimensional transition metal sulfides and Dirac half-metal materials, combined with a low dead-time circuit, the sensitivity and response speed problems of existing ultraviolet detectors under atmospheric background radiation and weak light signal environments are solved, achieving high-sensitivity and low-energy-consumption ultraviolet photodetection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG UNIV CITY COLLEGE
- Filing Date
- 2026-03-31
- Publication Date
- 2026-07-03
AI Technical Summary
Existing ultraviolet detectors struggle to achieve both high sensitivity and low dark current in environments with atmospheric background radiation and weak light signals. Furthermore, traditional equipment is bulky, fragile, and requires high-voltage power supplies, and complex optical systems are difficult to meet the needs of practical applications.
An ultraviolet photodetector based on a two-dimensional moiré superlattice structure is used, including a superlattice substrate, a photosensitive layer, a Schottky metal region, an anti-reflection layer, and electrodes. It utilizes twisted two-dimensional transition metal sulfide materials and Dirac half-metals or carbon-based materials to enhance photocurrent through Auger effect multiplication and exciton separation efficiency, combined with a low dead-time circuit design.
It achieves high sensitivity, high speed response and low dead time for ultraviolet light, adapts to a variety of optical detection scenarios, improves the flexibility and practicality of the detector, and reduces the complexity and energy consumption of the equipment.
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Figure CN122340919A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photodetector technology, and particularly relates to a highly sensitive, ultrafast response ultraviolet photodetector based on a two-dimensional moiré superlattice. Background Technology
[0002] With the development of modern photoelectric detection technology, the ultraviolet band has received increasing attention, becoming an important photoelectric detection technology after laser detection and infrared detection. Ultraviolet light in the 200–280 nm band is also known as solar-blind ultraviolet light. As the strongest light source, the solar spectrum covers the entire spectral region from extremely deep ultraviolet to extremely far infrared, directly or indirectly generating atmospheric background radiation, causing severe background interference to photoelectric detection systems operating near the ground and in adjacent space. This interference not only increases the burden on system signal processing but also generates false alarms.
[0003] In practical applications, due to the harsh atmospheric environment, the intensity of ultraviolet light from the target is usually low. The environment contains a large number of gas molecules or dust particles with strong absorption and scattering capabilities for ultraviolet light, resulting in a very weak ultraviolet light signal reaching the detector. Therefore, improving the detection capability of ultraviolet detectors for weak light is crucial. However, for most semiconductor photoconductive detectors, high responsivity is often accompanied by high dark current. Improving material quality and reducing defects lowers the dark current, but this reduces responsivity, making it difficult to improve the detector's detectivity. Traditional ultraviolet detection typically uses photomultiplier tubes or ultraviolet-enhanced silicon photodiodes; however, these devices are fragile, bulky, require high-voltage power supplies, and necessitate complex optical systems to block visible light and infrared photons. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a highly sensitive, ultrafast response ultraviolet photodetector based on a two-dimensional moiré superlattice.
[0005] Firstly, a highly sensitive, ultrafast-response ultraviolet photodetector based on a two-dimensional moiré superlattice is provided, including: Superlattice substrate, photosensitive layer, Schottky metal region, anti-reflection layer and electrodes; The photosensitive layer, the Schottky metal region, and the anti-reflection layer are sequentially arranged along the direction away from the superlattice substrate. The photosensitive layer comprises N stacked twisted two-dimensional transition metal sulfide materials, where N is an even number. The Schottky metal region is composed of hexagonal boron nitride and Dirac half-metal, or hexagonal boron nitride and carbon-based materials.
[0006] Preferably, the torsional two-dimensional transition metal sulfide material includes molybdenum disulfide and tungsten diselenide.
[0007] Preferably, the electrodes are located in the anti-reflection layer, the Schottky metal region, the photosensitive layer, and the superlattice substrate, respectively. The electrode in the Schottky metal region is used as the source electrode, the electrode in the photosensitive layer is used as the drain electrode, and the anti-reflection layer electrode and the superlattice substrate electrode together form the top back gate.
[0008] Preferably, the anti-reflection layer is made of aluminum oxide, and the superlattice substrate is made of sapphire.
[0009] In a second aspect, a method for fabricating an ultraviolet photodetector as described in any of the first aspects is provided, comprising: Step 1: Provide a superlattice substrate; Step 2: Spin-coat photoresist onto the superlattice substrate, and perform photolithography and development of the electrode pattern on the photoresist coating; then place the developed substrate into an electron beam evaporation device to perform electrode deposition and growth, and then remove the photoresist to form the corresponding electrode pattern; Step 3: Stack a two-dimensional transition metal sulfide layer at the corners of the substrate to form a photosensitive layer; the photosensitive layer is provided with electrodes; Step 4: Stack a Schottky metal region on the photosensitive layer; the Schottky metal region is provided with electrodes; Step 5: Sputter an anti-reflection layer over the Schottky metal region; the anti-reflection layer is made of aluminum oxide; electrodes are disposed on the aluminum oxide. Step 6: Lead wires to interconnect the electrodes on the aluminum oxide and the superlattice substrate; the electrodes on the aluminum oxide and the superlattice substrate together form the top gate and the back gate; the electrodes in the Schottky metal region form the source electrode, and the electrodes in the photosensitive layer form the drain electrode.
[0010] Preferably, in step 2, the spin coating of photoresist includes a low-speed spin coating stage and a high-speed spin coating stage, wherein the duration of the high-speed spin coating stage is longer than the duration of the low-speed spin coating stage.
[0011] Preferably, in step 3, two-dimensional transition metal sulfides are obtained by mechanical stripping or chemical vapor deposition, and corner stacking is achieved by cutting.
[0012] Preferably, in step 4, the Schottky metal region is composed of hexagonal boron nitride and Dirac half-metal, or hexagonal boron nitride and carbon-based material; the hexagonal boron nitride and Dirac half-metal or carbon-based material is obtained by mechanical exfoliation.
[0013] The beneficial effects of this invention are: 1. This invention utilizes the Fermi level of Dirac half-metals or carbon-based materials, which can be adjusted by an external voltage to achieve selective detection of the response wavelength. This tunable band detection capability enables the photodetector to adapt to various optical detection scenarios, significantly improving its application flexibility and practicality.
[0014] 2. This invention is based on the discovery and optimization of the strong coupling mechanism between ultraviolet photons and excitons in two-dimensional moiré superlattices. By enhancing Auger effect multiplication and exciton separation efficiency, a prototype detector that can efficiently capture and utilize ultraviolet photons is developed, achieving faster, more efficient and more sensitive ultraviolet detection. Attached Figure Description
[0015] Figure 1 A schematic diagram of the structure of a high-sensitivity, ultrafast-response ultraviolet photodetector based on a two-dimensional moiré superlattice provided by the present invention; Figure 2 A comparison chart of the responsivity of single-layer to multi-layer Dirac semimetals or carbon-based materials provided by the present invention.
[0016] Figure 3 The core circuit diagram of the avalanche detector provided by this invention. Detailed Implementation
[0017] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. Example 1:
[0018] To address the problems of the prior art, Embodiment 1 of this application provides a highly sensitive, ultrafast response ultraviolet photodetector based on a two-dimensional moiré superlattice, comprising: Superlattice substrate, photosensitive layer, Schottky metal region, anti-reflection layer and electrodes; The photosensitive layer, the Schottky metal region, and the anti-reflection layer are sequentially arranged along the direction away from the superlattice substrate. The photosensitive layer comprises N layers of twisted two-dimensional transition metal sulfide (TMDC) material, where N is an even number. The Schottky metal region is composed of hexagonal boron nitride and Dirac half-metal, or hexagonal boron nitride and carbon-based material.
[0019] Specifically, the torsional two-dimensional transition metal sulfide material includes molybdenum disulfide and tungsten diselenide. The torsional TMDC heterojunction (photosensitive layer) formed by tungsten diselenide and molybdenum disulfide facilitates the separation of interlayer ultraviolet excitons, thereby increasing photocurrent through Auger interaction, trapping separated hot electrons in the torsional moiré potential well, enhancing light absorption through the torsional TMDC superlattice, increasing photocurrent through ballistic avalanche, and raising the moiré potential through the topological insulating state cascade effect, thus improving the signal-to-noise ratio. Figure 1 As shown, the stacked photosensitive layer consists of six layers. By stacking the corner TMDC heterojunctions in a topological structure, high-efficiency optoelectronic performance, reliability, and integration are still maintained. The material thickness of each stack of photosensitive layers is approximately 0.3 nm. Furthermore, the TMDC material is not limited to the periodic moiré structure of Wse2 / Mos2.
[0020] Furthermore, assuming that the Schottky metal region is composed of hexagonal boron nitride and graphene (GR), the total thickness of the detector is controlled within 100 nm (excluding the superlattice substrate and the top oxide layer), and the thickness of the graphene layer is controlled at around 10 nm.
[0021] The electrodes are located in the anti-reflection layer, the Schottky metal region, the photosensitive layer, and the superlattice substrate, respectively. The source metal interconnect wires and the drain metal interconnect wires are connected to the Schottky metal region and the photosensitive layer, respectively (that is, the electrode in the Schottky metal region is used as the source electrode and the electrode in the photosensitive layer is used as the drain electrode). The anti-reflection layer electrode and the superlattice substrate electrode together form the top gate and the back gate.
[0022] The anti-reflection layer is made of aluminum oxide, and the superlattice substrate is made of sapphire to achieve the effect of anti-ultraviolet reflection.
[0023] In addition, such as Figure 3 As shown, this application provides a quenching circuit with a low dead time for a high-sensitivity, ultrafast-response ultraviolet photodetector based on a two-dimensional moiré superlattice. By combining passive quenching with the fast voltage drop of active components, an exceptionally short dead time can be achieved to maintain a low dead time. This circuit achieves a low dead time to improve photon detection efficiency.
[0024] like Figure 1 As shown, the ultraviolet photodetector provided in this application has the advantages of high sensitivity and high speed, quantum cascade structure, Schottky junction, and solar-blind ultraviolet phototransistor, and is the preferred structure for ultraviolet photodetectors.
[0025] like Figure 2 As shown, this application embodiment stacks corner TMDC heterojunctions with different numbers of layers (2, 4, 6, 8, and 10). The six devices were tested at different power levels, and their responsivity was calculated. It is clear that the number of layers is directly proportional to the responsivity.
[0026] like Figure 3 The diagram shown is the core circuit diagram of the detector provided in this application in a practical circuit scenario. Example 2:
[0027] Based on Example 1, Example 2 of this application provides a method for fabricating an ultraviolet photodetector, comprising: Step 1: Provide a superlattice substrate.
[0028] Step 2: Spin-coat photoresist onto the superlattice substrate, and perform photolithography and development of the electrode pattern on the photoresist coating; then place the developed substrate into an electron beam evaporation device to perform electrode deposition and growth, and then remove the photoresist to form the corresponding electrode pattern.
[0029] In step 2, the spin coating of photoresist includes a low-speed spin coating stage and a high-speed spin coating stage, wherein the duration of the high-speed spin coating stage is longer than the duration of the low-speed spin coating stage.
[0030] Step 3: Stack a two-dimensional transition metal sulfide layer at the corners of the substrate to form a photosensitive layer.
[0031] In step 3, two-dimensional transition metal sulfides are obtained by mechanical stripping or chemical vapor deposition, and corner stacking is achieved by cutting.
[0032] Step 4: Stack Schottky metal regions on the photosensitive layer; the photosensitive layer is provided with electrodes.
[0033] In step 4, the Schottky metal region is composed of hexagonal boron nitride and Dirac half-metal, or hexagonal boron nitride and carbon-based material; the hexagonal boron nitride and Dirac half-metal or carbon-based material grown by CVD is obtained by mechanical exfoliation; the Schottky metal region is provided with electrodes.
[0034] Step 5: Sputter an anti-reflection layer over the Schottky metal region; the anti-reflection layer is made of aluminum oxide; electrodes are disposed on the aluminum oxide.
[0035] Step 6: Lead wires to interconnect the electrodes on the aluminum oxide and the superlattice substrate. The electrodes on the aluminum oxide and the superlattice substrate together form the top gate and the back gate; the electrodes in the Schottky metal region form the source electrode, and the electrodes in the photosensitive layer form the drain electrode.
[0036] It should be noted that the method provided in this embodiment is the method corresponding to the product provided in Embodiment 1. Therefore, the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application. Example 3:
[0037] Based on Example 2, Example 3 of this application provides another method for fabricating an ultraviolet photodetector, including: Step 1: Provide sapphire as a substrate.
[0038] Step 2: After growing molybdenum disulfide on the substrate by vapor-source phase deposition, spin-coating photoresist is performed to pattern it. Electrodes of the molybdenum disulfide layer are obtained by sputtering, and excess photoresist is washed away.
[0039] Step 3: After growing tungsten diselenide on another substrate in the same manner as in Step 2, stack the two substrates at a certain rotation angle. Repeat the above steps multiple times to obtain a corner TMDC heterojunction stacked in a topological structure.
[0040] Step 4: Deposit a hexagonal boron nitride (h-BN) film on the surface of the heterojunction.
[0041] Specifically, h-BN films are prepared by chemical vapor deposition to provide excellent insulation properties and mechanical flexibility.
[0042] Step 5: Spin-coat PMMA as a support layer on the surface of Dirac semimetal or carbon-based material, transfer the Dirac semimetal or carbon-based material from the surface of deionized water to h-BN using a chemical method, and dry for a certain period of time to remove residual moisture.
[0043] Step 6: Spin-coat photoresist and perform overlay processing. After obtaining the electrode layer of Dirac semi-metal or carbon-based material by sputtering, wash away the excess photoresist.
[0044] Step 7: Deposit a hexagonal boron nitride (h-BN) film on the surface of a Dirac semimetal or carbon-based material. The method is similar to step 4 and will not be repeated here.
[0045] Step 8: Deposit another layer of aluminum oxide on top of h-BN.
[0046] Step 9: Spin-coat photoresist and perform overlay processing. Obtain the aluminum oxide layer electrode by sputtering. Wash away the excess photoresist and sputter the electrode on the bottom of the substrate in the same way. The details are not repeated here.
[0047] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 2 can be referred to each other, and will not be repeated in this application.
[0048] In summary, this application discovers and optimizes the strong coupling mechanism between ultraviolet photons and excitons in a two-dimensional moiré superlattice. By enhancing Auger effect multiplication and exciton separation efficiency, a prototype detector capable of efficiently capturing and utilizing ultraviolet photons is developed. The device in this application is a photodetector based on a twisted TMDC topology, achieving faster detection speed and higher response speed compared to existing detectors.
Claims
1. A high-sensitivity, ultrafast-response ultraviolet photodetector based on a two-dimensional moiré superlattice, characterized in that, include: Superlattice substrate, photosensitive layer, Schottky metal region, anti-reflection layer and electrodes; The system comprises a photosensitive layer, a Schottky metal region, and an anti-reflection layer arranged sequentially along a direction away from the superlattice substrate. The photosensitive layer consists of N stacked twisted two-dimensional transition metal sulfide materials, where N is an even number. The Schottky metal region is composed of hexagonal boron nitride and Dirac half-metal, or hexagonal boron nitride and carbon-based materials. The electrodes are located in the anti-reflection layer, the Schottky metal region, the photosensitive layer, and the superlattice substrate, respectively. The electrodes in the Schottky metal region serve as the source electrodes, the electrodes in the photosensitive layer serve as the drain electrodes, and the electrodes in the anti-reflection layer and the superlattice substrate together form the top gate and the back gate. The anti-reflection layer is made of aluminum oxide, and the superlattice substrate is made of sapphire.
2. The high-sensitivity, ultrafast-response ultraviolet photodetector based on a two-dimensional moiré superlattice according to claim 1, characterized in that, The torsion two-dimensional transition metal sulfide material includes molybdenum disulfide and tungsten diselenide.
3. A method for fabricating an ultraviolet photodetector as described in any one of claims 1 to 2, characterized in that, include: Step 1: Provide a superlattice substrate; Step 2: Spin-coat photoresist onto the superlattice substrate, and perform photolithography and development of the electrode pattern on the photoresist coating; The developed substrate is then placed in an electron beam evaporation apparatus to deposit and grow electrodes, and the photoresist is removed to form the corresponding electrode pattern. Step 3: Stack a two-dimensional transition metal sulfide layer at the corners of the substrate to form a photosensitive layer; the photosensitive layer is provided with electrodes; Step 4: Stack a Schottky metal region on the photosensitive layer; the Schottky metal region is provided with electrodes; Step 5: Sputter an anti-reflection layer over the Schottky metal region; the anti-reflection layer is made of aluminum oxide; electrodes are disposed on the aluminum oxide. Step 6: Lead wires to interconnect the electrodes on the aluminum oxide and the superlattice substrate; the electrodes on the aluminum oxide and the superlattice substrate together form the top gate and the back gate; the electrodes in the Schottky metal region form the source electrode, and the electrodes in the photosensitive layer form the drain electrode.
4. The method for fabricating an ultraviolet photodetector according to claim 3, characterized in that, In step 2, the spin coating of photoresist includes a low-speed spin coating stage and a high-speed spin coating stage, wherein the duration of the high-speed spin coating stage is longer than the duration of the low-speed spin coating stage.
5. The method for fabricating an ultraviolet photodetector according to claim 4, characterized in that, In step 3, two-dimensional transition metal sulfides can be obtained by mechanical stripping or chemical vapor deposition, and corner stacking can be achieved by cutting.
6. The method for fabricating an ultraviolet photodetector according to claim 5, characterized in that, In step 4, the Schottky metal region is composed of hexagonal boron nitride and Dirac half-metal, or hexagonal boron nitride and carbon-based material; the hexagonal boron nitride and Dirac half-metal or carbon-based material is obtained by mechanical exfoliation.