A two-dimensional noble metal chalcogenide-based near-infrared detector array and a preparation method and application thereof

Abstract

This invention relates to a near-infrared detector array based on two-dimensional noble metal chalcogenides, its fabrication method, and its applications, belonging to the field of image sensor technology. First, an underpotential deposition method is used to drive noble metal atoms to self-confinedly deposit on the silicon substrate surface using the potential difference between the noble metal and the silicon substrate, obtaining a wafer-level noble metal thin film. Then, chemical vapor deposition is used to sulfide, selenize, or tellurize the wafer-level noble metal thin film, transforming it in situ into a wafer-level two-dimensional noble metal chalcogenide thin film. Finally, a near-infrared detector array is fabricated using micro-nano fabrication processes. The two-dimensional noble metal chalcogenide near-infrared detector of this invention possesses advantages such as good mechanical flexibility, high mobility, and excellent stability, significantly improving the detector's detection performance.

Description

Technical Field

[0001] This invention belongs to the field of image sensor technology, and more specifically, relates to a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound, its preparation method and application. Background Technology

[0002] With the development of technology and the improvement of people's living standards, smart wearable devices are becoming increasingly popular in daily life, and the global wearable device market is expected to reach $150 billion by 2025. Photodetectors are the core component of wearable health devices, but currently commercially available wearable health devices mainly use rigid silicon-based photodetectors, which have drawbacks such as poor adhesion to the human body and inaccurate detection data. In contrast, photodetectors made of flexible materials have good adhesion to the human body, and can anchor to specific areas of the wearer even when the body is in motion, resulting in more accurate detection results and a higher fault tolerance. Current flexible photodetectors mainly use organic polymers, perovskites, and graphene, which suffer from problems such as low mobility, poor stability, and low light absorption, making it difficult to meet application requirements. Therefore, exploring suitable flexible semiconductor materials is key to developing high-performance flexible photodetectors and applying them to smart wearable devices. Summary of the Invention

[0003] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound, its fabrication method, and its application. Constructing a near-infrared detector array on a two-dimensional noble metal chalcogenide compound offers advantages such as good mechanical flexibility, high mobility, and excellent stability, significantly improving the detector's detection performance. This solves the technical problems of low mobility, poor stability, and low light absorption in existing photodetectors.

[0004] According to a first aspect of the present invention, a method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound is provided, comprising the following steps: (1) First, the underpotential deposition method is used to drive noble metal atoms to self-containedly deposit on the surface of the silicon substrate by utilizing the potential difference between the noble metal and the silicon substrate, so as to achieve uniform film formation of noble metal within the wafer range and obtain wafer-level noble metal thin film. (2) Chemical vapor deposition is used to sulfide, selenize or tellurize the wafer-level noble metal film, so that the wafer-level noble metal film is transformed in situ into a wafer-level two-dimensional noble metal chalcogenide film. (3) Photoresist is spin-coated onto the wafer-level two-dimensional noble metal chalcogenide thin film, and the source and drain electrodes are patterned by photolithography mask to obtain micro-nano electrode patterns with clear edge morphology. (4) Source and drain electrodes are deposited using electron beam evaporation, and then the residual photoresist is removed to obtain a near-infrared detector array based on two-dimensional noble metal chalcogenide compounds.

[0005] Preferably, step (1) specifically involves adding a silicon substrate to a hydrofluoric acid solution containing a noble metal precursor, and using the potential difference between the noble metal and the silicon substrate to drive the noble metal atoms to self-containedly deposit on the substrate surface.

[0006] Preferably, the noble metal is Pt or Pd.

[0007] Preferably, step (2) specifically involves: placing the wafer-level noble metal thin film in the central temperature zone of a tube furnace, placing a sulfur source, selenium source, or tellurium source in the upstream temperature zone of the tube furnace, adjusting the temperature of the central temperature zone to 400-600℃, reacting for 5-10 minutes, so that the wafer-level noble metal thin film is converted in situ into a wafer-level two-dimensional noble metal chalcogenide thin film.

[0008] Preferably, between steps (2) and (3), the wafer-level two-dimensional noble metal chalcogenide thin film is transferred onto a flexible substrate using a dry transfer method.

[0009] Preferably, the dry transfer specifically involves: subjecting the wafer-level two-dimensional noble metal chalcogenide film to oxygen plasma treatment, then spin-coating a transfer medium onto the film surface, and then vertically peeling it off using a heat-release tape; hot-pressing the tape onto a flexible substrate with a hydrophilic surface to transfer the wafer-level two-dimensional noble metal chalcogenide film onto the flexible substrate, and then removing the transfer medium to obtain the wafer-level two-dimensional noble metal chalcogenide film located on the flexible substrate.

[0010] Preferably, the transfer medium is polymethyl methacrylate.

[0011] Preferably, the flexible substrate is mica or polydimethylsiloxane.

[0012] According to another aspect of the present invention, a flexible near-infrared detector array based on a two-dimensional noble metal chalcogenide compound is provided.

[0013] According to another aspect of the present invention, the application of the aforementioned near-infrared detector array based on two-dimensional noble metal chalcogenides in the fabrication of wearable smart health monitoring devices is provided. Preferably, the wearable smart health monitoring device is used to detect heart rate, blood oxygen saturation, or blood pressure.

[0014] In summary, the fabrication method and application of the flexible near-infrared photodetector array based on two-dimensional noble metal chalcogenides described in this invention have the following advantages compared with existing achievements and technologies: (1) The two-dimensional noble metal chalcogenide of this invention adopts an underpotential deposition-in-situ conversion process, and the thin film can be prepared in a wafer-level controllable manner. Two-dimensional noble metal chalcogenides are a class of layered crystals with atomic-level thickness, which have good mechanical flexibility, high mobility, and excellent stability, and fully meet the requirements of flexible photodetectors. This type of two-dimensional material exhibits groundbreaking comprehensive performance: carrier mobility exceeds 200 cm² / (V·s); the band structure has a wide-range tunable characteristic of 0~1.8 eV; and in terms of mechanical flexibility, it can still maintain more than 90% of the original electrical properties at a curvature radius of 2 μm. Compared with the millisecond-level photoelectric delay (response time >10 ms) of traditional polymer semiconductors in the prior art, and the photoelectric conversion efficiency of graphene-based devices is generally less than 10%, the two-dimensional layered structure design based on two-dimensional noble metal chalcogenides has broken through the performance balance problem between response rate and energy conversion efficiency.

[0015] (2) The present invention employs an underpotential deposition-in-situ conversion strategy to deposit two-dimensional metal sulfide thin films, which can achieve high-quality, large-area uniform preparation of metal thin films. The provided method for preparing flexible near-infrared photodetector arrays based on two-dimensional noble metal chalcogenides is easy to operate and can realize the construction of photodetector arrays on various substrates, providing convenience for the integration and packaging of flexible photodetector devices.

[0016] (3) This invention has significant advantages in terms of flexibility, adaptability, response speed, and detection rate, and possesses stable photoelectric conversion capability and microsecond-level ultra-fast light response. It can effectively overcome the influence of factors such as signal noise and individual differences in complex scenarios, and accurately detect key human health indicators such as heart rate, blood oxygen saturation, and blood pressure. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the principle of the underpotential deposition technique used in Example 1.

[0018] Figure 2 It is the noble metal sulfide (PtS2) thin film prepared on a 1 × 1 cm silicon substrate obtained in Example 1.

[0019] Figure 3 This is a schematic diagram of the near-infrared detector structure constructed based on PtS2 in Example 1.

[0020] Figure 4 This is a flowchart of the near-infrared detector array constructed based on PtS2 thin film in Example 1.

[0021] Figure 5 This is a schematic diagram of the near-infrared detector array constructed based on PtS2 thin film in Example 1.

[0022] Figure 6 The light response of the near-infrared detector constructed in Example 1 under different light intensities is shown, with 10 light pulses.

[0023] Figure 7 This is a schematic diagram illustrating the principle of measuring blood oxygen saturation using a near-infrared photodetector constructed in Example 1. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] The two-dimensional noble metal chalcogenide thin film of this invention is prepared by first employing an underpotential deposition strategy, utilizing the high potential difference between the noble metal and the substrate to drive the self-confined deposition of metal atoms on the substrate surface, achieving uniform film formation within the wafer. Then, in-situ conversion processes are used to achieve sulfidation, selenization, and tellurization of the wafer-level noble metal thin film, thereby realizing the preparation of a wafer-level two-dimensional noble metal chalcogenide thin film. The thin film of this invention possesses wafer-level controllable preparation. A flexible near-infrared detector array based on two-dimensional noble metal chalcogenide includes, from bottom to top, a substrate, a two-dimensional noble metal chalcogenide, and source / drain electrodes.

[0026] In some embodiments, the two-dimensional noble metal chalcogenide thin films include, but are not limited to, PtTe2, PtSe2, PtS2, PdTe2, PdSe2, PdS2, etc.

[0027] In some embodiments, the two-dimensional noble metal chalcogenide film is a wafer-level continuous film with a diameter of 2 inches or 4 inches and a smooth surface.

[0028] In some embodiments, the flexible near-infrared detector array is based on a two-dimensional noble metal chalcogenide compound, and the source and drain electrodes include, but are not limited to, gold, silver, platinum, copper, graphene, ITO, or aluminum. The substrate includes, but is not limited to, silicon, mica, glass, or PDMS.

[0029] This invention also provides a method for preparing a flexible near-infrared detector array of two-dimensional noble metal chalcogenides, comprising the following steps: (1) Two-dimensional noble metal chalcogenide thin films are prepared on a substrate.

[0030] (2) Near-infrared detector arrays are fabricated using micro-nano fabrication technology. The micro-nano fabrication technology involves first exposing the electrode pattern and then depositing the electrode.

[0031] The two-dimensional noble metal chalcogenide thin film in step (1) is prepared on a single-crystal silicon substrate by an underpotential deposition-in-situ conversion strategy, or by mechanically transferring the two-dimensional noble metal chalcogenide thin film on the silicon substrate to other substrates (such as mica or PDMS).

[0032] The underpotential deposition environment described in step (1) is an atmospheric environment, and the deposition time is 5~20 min.

[0033] The exposure electrode method in step (2) is one of electron beam exposure, photolithography, or laser direct writing. The deposition electrode method is one of thermal evaporation deposition, magnetron sputtering deposition, or electron beam deposition.

[0034] In some embodiments, the exposure electrode uses one of electron beam lithography, photolithography, or laser direct writing to create a pattern on the surface of a two-dimensional metal sulfide so that some areas of the two-dimensional metal sulfide are covered and protected, while other areas are exposed.

[0035] The following are specific examples.

[0036] Example 1 The present invention fabricates a near-infrared detector array based on two-dimensional PtS2, specifically as follows: (1) Two-dimensional PtS2 thin films were prepared on single-crystal silicon substrates using an underpotential deposition-in-situ conversion strategy. Platinum powder was used as a raw material and prepared as a platinum precursor in hydrofluoric acid solution. The pretreated single-crystal silicon substrate was placed in the reaction solution. The high potential difference between the noble metal and the single-crystal silicon substrate was used to drive platinum atoms to self-containedly deposit on the surface of the single-crystal silicon substrate to form a wafer-level platinum atom thin film. The substrate was then placed in a tube furnace with the sulfur source placed in the upstream temperature zone of the tube furnace and the temperature of the central temperature zone adjusted to 600 °C. The reaction was carried out for 10 min and then naturally cooled to obtain two-dimensional PtS2 thin films. (2) Photoresist was spin-coated onto a two-dimensional PtS2 thin film, and the source and drain electrodes were patterned using a photomask. After exposure, the electrodes were treated with a developer for 45 s to obtain micro / nano electrode patterns with clear edge morphology. (3) A 10 nm Cr / 50 nm Au electrode was deposited using electron beam evaporation. Then, a lift-off process was used to remove the residual photoresist. Specifically, the sample was immersed in a 60 °C acetone solution for 5 min to remove the residual photoresist, and then washed with anhydrous ethanol and ultrapure water in sequence. Finally, it was gently dried with nitrogen gas to complete the fabrication of the PtS2-based detector source and drain electrodes.

[0037] Figure 1This is a schematic diagram of the underpotential deposition technique used in Example 1. It illustrates the microscopic electrochemical process and band potential principle of the self-confined growth of noble metal atoms on the silicon substrate surface in the underpotential deposition technique. In a solution system containing fluoride ions, the spontaneous potential difference between silicon and noble metal complex ions constitutes the driving force for deposition because the oxidation potential of silicon is significantly lower than the reduction potential of the noble metal complex ions. The silicon substrate locally loses electrons and is oxidized and dissolved, while the noble metal complex ions in the solution gain electrons and are reduced and deposited on the silicon surface. When the surface is covered by a complete layer of noble metal atoms, the underlying silicon is physically blocked, the galvanic cell reaction automatically stops, thereby achieving extremely uniform atomic layer self-confined deposition at the wafer level.

[0038] Figure 2 This is a macroscopic photograph of a two-dimensional continuous PtS2 thin film prepared on a 1 × 1 cm single-crystal silicon substrate using the aforementioned underpotential deposition combined with in-situ conversion process. It can be seen that the synthesized two-dimensional film completely and uniformly covers the substrate surface, exhibiting a flat and continuous dark morphology.

[0039] Figure 3 This is a schematic cross-sectional view of a single near-infrared photodetector device constructed based on this PtS2 thin film. The device employs a bottom-gate top-contact field-effect transistor configuration. The gray light bar in the center of the figure illustrates the working state when near-infrared light is perpendicularly irradiated onto the two-dimensional material channel region.

[0040] Figure 4 This is a flowchart of the near-infrared detector array constructed based on PtS2 in Example 1. First, a photoresist layer is spin-coated onto the thin film surface on a wafer substrate; then, exposure and development are performed using a photomask to cut out the designed array electrode pattern on the photoresist; next, an electron beam evaporation technique is used to cover the entire sample surface with a metal electrode layer; finally, an organic solvent is used to peel off the remaining photoresist along with the attached metal, ultimately leaving a high-precision metal transistor array structure on the substrate thin film.

[0041] Figure 5 This image shows the overall appearance and a magnified 3D schematic of a wafer-level near-infrared detector array constructed based on a 2D PtS2 thin film. The left side shows multiple device array modules regularly distributed on a circular wafer, demonstrating the mass production potential of this fabrication process for large areas and high integration. The magnified view on the right side shows in detail one of the high-density 10 × 10 pixel micro-nano photodetector arrays, with each independent detection unit arranged in a matrix pattern.

[0042] Figure 6 This refers to the light response of the near-infrared detector constructed based on PtS2 in Example 1 under different light intensities, with 10 light pulses. Figure 6As can be seen, under periodic illumination of 10 consecutive near-infrared light pulses, the detector's photocurrent exhibits a step-like response highly synchronized with the light pulses. The curves of different shades of gray in the figure represent the test results of the device under different incident light intensities. This curve strongly demonstrates that the detector not only has extremely fast response speed and recovery capability to near-infrared light, but also that its photoelectric response maintains excellent operational stability under multiple illumination cycles.

[0043] Figure 7 This diagram illustrates the application scenario of measuring heart rate and blood oxygen saturation based on this two-dimensional flexible near-infrared photodetector array. The diagram shows that during system operation, near-infrared and red light emitted by LEDs penetrate the skin and illuminate subcutaneous blood vessels. Due to the significant differences in absorption and reflection characteristics of these two wavelengths of light between oxygen-rich and hypoxic cells in the blood vessels, the reflected characteristic light signals are precisely captured by the high-density attached two-dimensional detector array. Utilizing the high spatial resolution and high responsivity of the array, the drawbacks of traditional single-point devices, which are susceptible to motion noise interference, are effectively overcome, thus accurately resolving core physiological indicators such as blood oxygen and heart rate.

[0044] Example 2 A two-dimensional PtSe2 near-infrared detector array based on a mica substrate was fabricated using a dry transfer method, comprising the following steps: (1) Two-dimensional PtSe2 thin films were prepared on single-crystal silicon substrates using an underpotential deposition-in-situ conversion strategy. The pre-processing steps were the same as in Example 1, with the key difference being that the sulfur source placed in the upstream temperature zone of the tube furnace was replaced with a selenium source, and the reaction temperature in the central temperature zone was adjusted to 700 °C. After the reaction was completed, the film was naturally cooled to obtain two-dimensional PtSe2 thin films. (2) The two-dimensional PtSe2 film based on the silicon substrate is subjected to oxygen plasma treatment, and a PMMA layer with a thickness of 300 nm is spin-coated on the surface of the film. Then, the heat release tape is flatly attached to it and vertically peeled off to remove the two-dimensional PtSe2 film from the silicon substrate. (3) Immerse the mica sheet in a HCl / H2O2 mixture with a volume ratio of 1:1 for 10 min, then rinse it with deionized water and blow it dry to obtain a hydroxylated hydrophilic surface. (4) Attach the side of the tape with the film peeled off in step (2) to the mica sheet, heat it to 80 ℃ and apply 0.5 MPa pressure simultaneously for 60 s, so that the heat release tape loses its stickiness and peels off automatically when heated. (5) After gradient cooling to room temperature, the PMMA layer was removed sequentially with acetone (60 °C) and isopropanol. A two-dimensional PtSe2 film on a mica substrate was obtained. (6) Photoresist was spin-coated onto a two-dimensional PtSe2 thin film, and the source and drain electrodes were patterned using a photomask. After exposure, the electrode was treated with a developer for 45 s to obtain micro / nano electrode patterns with clear edge morphology; (7) A 10 nm Cr / 50 nm Au electrode was deposited using an electron beam evaporation process. Then, a stripping process was used to remove the residual photoresist. Specifically, the sample was immersed in a 60 °C acetone solution for 5 min to remove the residual photoresist, and then washed with anhydrous ethanol and ultrapure water in sequence. Finally, it was gently dried with nitrogen gas to complete the fabrication of the PtSe2-based detector source and drain electrodes.

[0045] Example 3 A two-dimensional PtSe2 near-infrared detector array based on a PDMS flexible substrate was fabricated using a dry transfer method, comprising the following steps: (1) Two-dimensional PtSe2 thin films were prepared on single-crystal silicon substrates using the same underpotential deposition-in-situ conversion strategy as in Example 1, except that the sulfur source placed in the upstream temperature zone of the tube furnace was replaced with a selenium source and the temperature of the central temperature zone was adjusted to 700 °C. (2) The two-dimensional PtSe2 film based on the single crystal silicon substrate is subjected to oxygen plasma treatment, and a double layer of PMMA is spin-coated on the surface of the film as a protective layer. Then, the heat release tape is flatly attached to it and vertically peeled off, so that the two-dimensional PtSe2 film is separated from the single crystal silicon substrate. (3) The PDMS flexible substrate is subjected to oxygen plasma treatment, and immediately coated with a 1% APTES ethanol solution by spin coating on its surface for surface modification, followed by drying to remove the solvent; (4) Under a microscope, the heat release tape with the thin film is precisely positioned on the modified PDMS substrate. First, a pressure of 0.2 MPa is applied to make it adhere tightly. Then, the temperature is raised to 120 °C and maintained for 60 s, so that the tape loses its stickiness and peels off automatically. (5) After gradient cooling to room temperature, the PMMA layer on the surface is removed sequentially with acetone and isopropanol at 60 °C to obtain a two-dimensional PtSe2 film on a PDMS substrate. (6) Photoresist is spin-coated onto the two-dimensional PtSe2 thin film, exposed through a photomask, and then treated with a developer for 45 s to obtain a micro-nano electrode pattern with clear edge morphology. (7) Electron beam evaporation was used to deposit Cr / Au metal layers with thicknesses of 10 nm and 50 nm as electrodes. Then, a stripping process was used to remove the residual photoresist. Specifically, the sample was immersed in acetone at 60 °C for 5 min to remove the residual photoresist, then washed with anhydrous ethanol and ultrapure water in sequence, and finally gently dried with nitrogen gas to complete the fabrication of the PtSe2-based detector source and drain electrodes.

[0046] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound, characterized in that, Includes the following steps: (1) First, the underpotential deposition method is used to drive noble metal atoms to self-containedly deposit on the surface of the silicon substrate by utilizing the potential difference between the noble metal and the silicon substrate, so as to achieve uniform film formation of noble metal within the wafer range and obtain wafer-level noble metal thin film. (2) Chemical vapor deposition is used to sulfide, selenize or tellurize the wafer-level noble metal film, so that the wafer-level noble metal film is transformed in situ into a wafer-level two-dimensional noble metal chalcogenide film. (3) Photoresist is spin-coated onto the wafer-level two-dimensional noble metal chalcogenide thin film, and the source and drain electrodes are patterned by photolithography mask to obtain micro-nano electrode patterns with clear edge morphology. (4) Source and drain electrodes are deposited using electron beam evaporation, and then the residual photoresist is removed to obtain a near-infrared detector array based on two-dimensional noble metal chalcogenide compounds.

2. The method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound as described in claim 1, characterized in that, The specific step (1) is as follows: the silicon substrate is added to a hydrofluoric acid solution containing a noble metal precursor, and the noble metal atoms are driven to self-containedly deposit on the substrate surface by utilizing the potential difference between the noble metal and the silicon substrate.

3. The method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound as described in claim 1 or 2, characterized in that, The precious metal is Pt or Pd.

4. The method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound as described in claim 1, characterized in that, The specific steps (2) are as follows: placing the wafer-level noble metal thin film in the central temperature zone of a tube furnace, placing the sulfur source, selenium source or tellurium source in the upstream temperature zone of the tube furnace, adjusting the temperature of the central temperature zone to 400-600℃, reacting for 5-10 minutes, so that the wafer-level noble metal thin film is transformed in situ into a wafer-level two-dimensional noble metal chalcogenide thin film.

5. The method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound as described in claim 1, characterized in that, Between steps (2) and (3), the wafer-level two-dimensional noble metal chalcogenide thin film is transferred onto a flexible substrate using a dry transfer method.

6. The method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound as described in claim 5, characterized in that, The dry transfer method specifically involves: subjecting the wafer-level two-dimensional noble metal chalcogenide film to oxygen plasma treatment, then spin-coating a transfer medium onto the film surface, and then vertically peeling it off using a heat-release tape; hot-pressing the tape onto a flexible substrate with a hydrophilic surface to transfer the wafer-level two-dimensional noble metal chalcogenide film onto the flexible substrate, and then removing the transfer medium to obtain the wafer-level two-dimensional noble metal chalcogenide film located on the flexible substrate.

7. The method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound as described in claim 6, characterized in that, The transfer medium is polymethyl methacrylate.

8. The method for fabricating a near-infrared detector array based on a two-dimensional noble metal chalcogenide compound as described in claim 6 or 7, characterized in that, The flexible substrate is mica or polydimethylsiloxane.

9. A flexible near-infrared detector array based on a two-dimensional noble metal chalcogenide prepared by any one of claims 1-8.

10. The application of the near-infrared detector array based on two-dimensional noble metal chalcogenides as described in claim 9 in the fabrication of wearable smart health monitoring devices; Preferably, the wearable smart health monitoring device is used to detect heart rate, blood oxygen saturation, or blood pressure.

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