Multimode photodetector and method of making the same

Abstract

The application provides a multi-mode photodetector and a preparation method thereof, and belongs to the technical field of photoelectricity. The multi-mode photodetector comprises a substrate, a functional layer and an electrode. The functional layer is arranged on the substrate, and the functional layer comprises a molybdenum disulfide material; the electrode is arranged on the functional layer; and in the functional layer, the molybdenum disulfide material has a 1T phase and a 2H phase. The multi-mode photodetector has the ability of multi-response mode dynamic switching, and in different working scenes, the photodetector can flexibly switch the response mode according to actual requirements, so that effective detection of various scenes is realized, and the limitation of the traditional photodetector which only has a single conductive effect detection mode is broken.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronics, and in particular to a multi-mode photodetector and a preparation method thereof. BACKGROUND

[0002] As the sensing core of modern optoelectronic information systems, the performance of photodetectors directly determines the detection sensitivity, environmental adaptability and functional expandability of optoelectronic systems. Under the traditional technical framework, photodetectors mostly use fixed material systems to realize the conversion of optical signals to electrical signals through single physical structures such as PN junctions, PIN junctions or avalanche diodes. The response wavelength band and working mode of such devices are strictly limited by physical parameters such as material band gap, device geometric configuration and electrode arrangement during the preparation stage, resulting in the need for multiple-band imaging systems to be realized through optical elements or detector array splicing, which significantly increases the complexity of the optical system.

[0003] With the iterative upgrade of intelligent sensing technology, the application requirements of dynamic and multi-scene fusion have put forward requirements for multi-detection modes of single-film photodetectors. For example, in the field of autonomous driving, laser radars need to dynamically switch between the 1550nm eye-safe band and the 905nm high-sensitivity band to adapt to different weather conditions; in quantum communication systems, photodetectors are required to quickly reconfigure between single-photon counting mode and linear detection mode. The traditional solution relies on mechanical or electronic switching of multiple independent detector modules, which not only leads to a doubling of the system size, but also causes a significant increase in power consumption due to circuit redundancy, making it difficult to meet the stringent requirements of portable devices and low-orbit satellite payloads.

[0004] Therefore, it is necessary to design a multi-mode photodetector and a preparation method thereof to improve the above problems. SUMMARY

[0005] In view of the above shortcomings of the prior art, the present application provides a multi-mode photodetector and a preparation method thereof to solve the technical problem that photodetectors are difficult to realize multiple dynamic switching response modes in a single material film layer due to limitations on material band gap, device configuration and other parameters.

[0006] To achieve the above object and other related objects, the present application provides a multi-mode photodetector, which comprises a substrate, a functional layer and an electrode.

[0007] The functional layer is arranged on the substrate, and the functional layer comprises a molybdenum disulfide material; the electrode is arranged on the functional layer; in the functional layer, the molybdenum disulfide material has a 1T phase and a 2H phase.

[0008] In an example of the present application, the functional layer has a capacitor structure formed by 1T phase molybdenum disulfide and 2H phase molybdenum disulfide.

[0009] In an example of the present application, the multi-mode photodetector has a conductive detection mode when a bias voltage is applied, and has a capacitive detection mode or a photovoltaic detection mode when no bias voltage is applied.

[0010] In an example of the present application, when the functional layer thickness is less than 31 nm, the multi-mode photodetector has a capacitive detection mode when no bias voltage is applied, and has a conductive detection mode when a bias voltage is applied.

[0011] In an example of the present application, when the functional layer thickness is greater than or equal to 31 nm, the multi-mode photodetector has a photovoltaic detection mode when no bias voltage is applied, and has a conductive detection mode when a bias voltage is applied.

[0012] The present application also provides a method for preparing a multi-mode photodetector, comprising the following steps:

[0013] providing a substrate;

[0014] electrochemically intercalating a molybdenum disulfide raw material;

[0015] preparing a molybdenum disulfide nanosheet solution using the molybdenum disulfide raw material;

[0016] coating the molybdenum disulfide nanosheets on the surface of the substrate, and forming a functional layer on the surface of the substrate after drying;

[0017] plating an electrode on the functional layer to form a multi-mode photodetector.

[0018] In an example of the present application, the step of providing a substrate further comprises: performing a hydrophilic treatment on the surface of the substrate.

[0019] In an example of the present application, the step of electrochemically intercalating a molybdenum disulfide raw material comprises: placing a bulk carbon material and the molybdenum disulfide raw material into an intercalation agent solution; applying a voltage to the intercalation agent solution to electrochemically intercalate the molybdenum disulfide raw material, so that the molybdenum disulfide raw material has a 1T phase and a 2H phase.

[0020] In an example of the present application, the step of preparing a molybdenum disulfide nanosheet solution using the molybdenum disulfide raw material comprises: crushing the molybdenum disulfide raw material to obtain molybdenum disulfide nanosheets; and dispersing the molybdenum disulfide nanosheets into an organic solvent to obtain a molybdenum disulfide nanosheet solution.

[0021] The application provides a multi-mode photoelectric detector, which integrates a 1T phase structure and a 2H phase structure of a molybdenum disulfide material in a same functional layer film, so that the device functional layer has an atomic-level heterogeneous integration capability, and the capacitor-conductance dual detection mode is realized in a single material functional layer of the device, thereby having the advantages of multiple functions, a simplified structure, a small size and easy integration.

[0022] The multi-mode photoelectric detector has the capability of dynamically switching multiple response modes, and in different working scenes, the detector can flexibly switch the response mode according to actual requirements, so that effective detection of multiple scenes is realized, and the limitation of the traditional photoelectric detector with only a single conductance effect detection mode is broken. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other embodiments can also be obtained from these drawings without creative labor.

[0024] Figure 1 FIG. 1 is a structural schematic diagram of a multi-mode photoelectric detector in an embodiment of the application;

[0025] Figure 2 FIG. 2 is a photoelectric detection data diagram of the capacitor detection mode and the conductance detection mode of the multi-mode photoelectric detector in an embodiment of the application under the irradiation of a wavelength 532nm laser;

[0026] Figure 3 FIG. 3 is a Raman spectrum test diagram of the functional layer of the multi-mode photoelectric detector in an embodiment of the application;

[0027] Figure 4 FIG. 4 is an absorption spectrum test diagram of the multi-mode photoelectric detector in an embodiment of the application when the thickness of the functional layer is 23nm and 50nm;

[0028] Figure 5 FIG. 5 is a flowchart of a preparation method of the multi-mode photoelectric detector in an embodiment of the application;

[0029] Figure 6 FIG. 6 is a preparation process flowchart of the multi-mode photoelectric detector in an embodiment of the application;

[0030] Figure 7 FIG. 7 is a flowchart of step S2 in an embodiment of the application;

[0031] Figure 8 FIG. 8 is a flowchart of step S3 in an embodiment of the application.

[0032] Element No.

[0033] 10, substrate; 20, functional layer; 30, electrode. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0035] It should be noted that the diagrams provided in the embodiments only schematically illustrate the basic concept of the present application, and only the components related to the present application are shown in the diagrams, rather than being drawn according to the number, shape and size of the components in actual implementation. The shape, number and proportion of each component in actual implementation can be arbitrarily changed, and the layout pattern of the components can be more complex.

[0036] In the present application, it should be noted that, if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like appear, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first" and "second" appear, they are only for description and distinction purposes, and cannot be understood as indicating or implying relative importance.

[0037] In one aspect, referring to Figures 1 to 3 The present application provides a multi-mode photodetector, which introduces a molybdenum disulfide film with 1T phase and 2H phase in a functional layer to realize dynamically switchable capacitance and conductance dual-mode detection in a single device.

[0038] Referring to Figure 1The aforementioned multimode photodetector includes a substrate 10, a functional layer 20, and an electrode 30. The substrate 10 can be made of a semiconductor material or an insulating material. The semiconductor material can be, for example, single-crystal silicon (Si), single-crystal germanium (Ge), silicon-germanium (SiGe), or silicon carbide (SiC). The insulating material can be an organic insulator, an inorganic insulator, or a combination thereof; for example, the insulating material can be silicon oxide (SiO2). The functional layer 20 is disposed on the substrate 10 and includes a molybdenum disulfide material, for example, the functional layer 20 is a molybdenum disulfide thin film after electrochemical intercalation. The electrode 30 is disposed on the functional layer 20 and is used to apply a bias voltage to the multimode photodetector and to extract the photocurrent generated by the functional layer 20 in response to illumination.

[0039] like Figure 3 As shown, in functional layer 20, the molybdenum disulfide material simultaneously possesses both 1T and 2H phase structures. The Raman spectrum of functional layer 20 reveals the presence of the 2H-MoS2 Raman peak E. 1 2g and A 1g (located at 383.2cm respectively) -1 and 406.8cm -1 (location), and also the Raman peak of 1T-MoS2 (located at 148.4 cm). -1 237.4cm -1 and 301.6cm -1 (place).

[0040] In the multi-mode photodetector, functional layer 20 simultaneously possesses a capacitor structure formed by stacked 1T-phase molybdenum disulfide nanosheets and a heterojunction structure formed by the composite of 1T-phase molybdenum disulfide and 2H-phase molybdenum disulfide. 1T-phase molybdenum disulfide, as an octahedral coordinated metallic phase, can form a distributed planar capacitor network in functional layer 20 due to its high carrier mobility and loose van der Waals stacking. The van der Waals stacked 1T-phase molybdenum disulfide uses the inter-sheet space as a "dielectric layer" and the nanosheets on both sides of the inter-sheet space as "electrode plates," thus possessing a capacitor structure that can efficiently capture and store photogenerated carriers through quantum capacitance effects. 2H-phase molybdenum disulfide, as a triangular prism coordinated semiconductor phase, can absorb photons to generate electron-hole pairs, providing a carrier source for the capacitance effect. The heterostructure formed by the coexistence of these two phases exhibits a significant capacitance effect, with the 1T-phase capacitor network dominating photocurrent storage when there is no bias voltage.

[0041] Due to the capacitive effect structure and heterojunction structure formed by the composite of 1T-phase and 2H-phase molybdenum disulfide introduced into the functional layer 20 of the multi-mode photodetector, in some embodiments, when a bias voltage is applied, the internal 1T-phase molybdenum disulfide exhibits conductive properties under the action of the external voltage, directly transmitting photogenerated carriers generated by the 2H-phase molybdenum disulfide under illumination, thus enabling the multi-mode photodetector to exhibit a conductive detection mode; when no bias voltage is applied, the internal composite of 1T-phase and 2H-phase molybdenum disulfide exhibits capacitive properties, which can capture photogenerated carriers generated by the 2H-phase molybdenum disulfide under illumination, enabling the multi-mode photodetector to exhibit a photovoltaic detection mode or a capacitive detection mode.

[0042] In addition, such as Figure 4 As shown, the functional layer 20 utilizes the synergistic effect of 1T phase and 2H phase molybdenum disulfide materials to further expand the optical response band of the multi-mode photodetector, thereby covering a wider detection band and realizing photoelectric detection of more types of optical signals, thus greatly improving the versatility and adaptability of the detector.

[0043] In some embodiments, when the thickness of the functional layer 20 is less than 31 nm, the multi-mode photodetector has a capacitance detection mode when no bias voltage is applied, and a conductivity detection mode when a bias voltage is applied. Therefore, the multi-mode photodetector has a dynamically switchable capacitance detection mode and conductivity detection mode. For example... Figure 2 As shown in one example, a multi-mode photodetector with a functional layer 20 thickness of 23 nm is provided. When no bias voltage is applied, this multi-mode photodetector exhibits a capacitive photoelectric response under irradiation with a 45 μW 532 nm laser. The response behavior in the capacitive detection mode is a spike-pulse signal output, i.e., responding to one light input with two outputs of positive and negative electrical signals. When a 2 V bias voltage is applied, this multi-mode photodetector forms a stable photocurrent under irradiation with a 45 μW 532 nm laser, thus exhibiting a conductive photoelectric response. The response behavior in the conductive detection mode is a rectangular square wave signal output, i.e., responding to one light input with one electrical signal output. It should be noted that the magnitude of the photocurrent generated by the multi-mode photodetector in the conductive detection mode depends on the absorbance of the 2H phase molybdenum disulfide material to the incident wavelength light, while the magnitude of the photocurrent generated by the multi-mode photodetector in the capacitive detection mode depends on the charging and discharging capability and efficiency of the planar capacitor formed by the 1 T phase molybdenum disulfide nanosheets.

[0044] like Figure 2As shown, with the increase of the thickness of the functional layer 20, the absorption rate of the molybdenum disulfide material within the functional layer 20 for the incident laser also increases. When the thickness of the functional layer 20 is greater than or equal to 31 nm, the multi-mode photodetector exhibits a photovoltaic detection mode when no bias voltage is applied, and a conductivity detection mode when a bias voltage is applied. For example... Figure 2 As shown, in one example, a multi-mode photodetector with a functional layer 20 thickness of 31 nm is provided. When no bias voltage is applied, this multi-mode photodetector exhibits a photovoltaic photoresponse under irradiation with a 532 nm laser of 45 μW. The response behavior in photovoltaic detection mode is a rectangular square wave signal output, i.e., responding to one light input with one electrical signal output. When a bias voltage of 2 V is applied, this multi-mode photodetector generates a stable photocurrent under irradiation with a 532 nm laser of 45 μW, thus exhibiting a conductive photoresponse. It should be noted that the magnitude of the photocurrent generated by the multi-mode photodetector in photovoltaic detection mode depends on the built-in electric field strength generated by the heterojunction formed by the 2H phase and 1T phase molybdenum disulfide materials.

[0045] Furthermore, it should be noted that the type of electrode 30 used in the multi-mode photodetector is not limited. For example, electrode 30 can be selected from various forms such as interdigitated electrodes, counter electrodes, or external lead electrodes. The material of electrode 30 can be any suitable conductive material, such as metal, graphene, or MXene.

[0046] Please see Figure 5 and Figure 6 On the other hand, this application also provides a method for fabricating a multi-mode photodetector, the method comprising the following steps:

[0047] S1. Provide substrate 10;

[0048] S2. Electrochemical intercalation treatment of molybdenum disulfide raw material;

[0049] S3. Prepare molybdenum disulfide nanosheet solution using the molybdenum disulfide raw material;

[0050] S4. The molybdenum disulfide nanosheets are coated onto the surface of the substrate 10, and a functional layer 20 is formed on the surface of the substrate 10 after drying.

[0051] S5. Electrode 30 is deposited on the functional layer 20 to form a multi-mode photodetector.

[0052] In some embodiments, step S1 further includes a pretreatment step for the substrate 10, which includes first cleaning and drying the surface of the substrate 10, and then performing a hydrophilic treatment on the surface of the substrate 10 to facilitate the adsorption of molybdenum disulfide nanosheet solution.

[0053] It should be noted that the method of cleaning, drying and hydrophilic treatment of the substrate 10 surface is not limited. For example, in one example, the pretreatment steps include ultrasonic cleaning of the substrate 10 in deionized water and alcohol in sequence, drying the residual liquid on the surface of the substrate 10 with nitrogen gas after cleaning, and placing the cleaned substrate 10 into a plasma machine (such as PLASMA CLEAVER plasma) for surface hydrophilic treatment at the High setting for 5 minutes.

[0054] In step S2, electrochemical intercalation treatment is performed on the molybdenum disulfide material to introduce 1T and 2H phase structures into the molybdenum disulfide material. Specifically, as follows... Figure 7 As shown, in some embodiments, step S2 includes the following steps:

[0055] S21. Place the bulk carbon material and molybdenum disulfide raw material into the intercalating agent solution.

[0056] In step S21, the bulk carbon material and the bulk molybdenum disulfide raw material are placed into the intercalating agent solution, which can be a tetraheptylammonium bromide solution.

[0057] S22. Apply voltage to the intercalating agent solution to electrochemically intercalate the molybdenum disulfide raw material, so that the molybdenum disulfide raw material has a 1T phase and a 2H phase.

[0058] In step S22, the positive and negative electrodes are placed in the intercalating agent solution, and a power source is connected between the positive and negative electrodes to apply a DC voltage (such as 10V) to the intercalating agent solution, thereby performing electrochemical intercalation treatment on the molybdenum disulfide raw material in the intercalating agent solution, so that the molybdenum disulfide raw material has both 1T phase and 2H phase structure.

[0059] like Figure 8 As shown, in some embodiments, step S3 includes the following steps:

[0060] S31. The molybdenum disulfide raw material after electrochemical intercalation is pulverized to obtain molybdenum disulfide nanosheets.

[0061] In step 31, the blocky molybdenum disulfide raw material after electrochemical intercalation is placed into a pulverizer for pulverization and peeling, and the pulverized fragments are collected to obtain molybdenum disulfide nanosheets.

[0062] S32. Disperse the molybdenum disulfide nanosheets in an organic solvent to obtain a molybdenum disulfide nanosheet solution.

[0063] In step S32, the molybdenum disulfide nanosheets are placed in an organic solvent and centrifuged at high speed to obtain a clean molybdenum disulfide nanosheet solution. Isopropanol solution can be used as the organic solvent.

[0064] In some embodiments, step S4 includes drop-coating a molybdenum disulfide nanosheet solution onto a substrate 10, and then placing the substrate 10 on a heating stage for drying to completely evaporate the organic solvent in the molybdenum disulfide nanosheet solution on the substrate 10, such as heating at a temperature of 80°C for a heating time of 5 minutes, thereby forming a functional layer 20 composed of a molybdenum disulfide thin film on the substrate 10.

[0065] In some embodiments, step S5 includes depositing an electrode 30 on the surface of the functional layer 20 using an electron beam evaporation apparatus and a metal mask to fabricate a multimode photodetector.

[0066] In summary, the multi-mode photodetector and its fabrication method of this invention integrate molybdenum disulfide materials with 1T and 2H phase structures into the same functional layer thin film, enabling atomic-level heterogeneous integration of the device's functional layer. This allows for the realization of dual detection modes of capacitance and conductivity within a single material functional layer, thus combining the advantages of diverse functions, simplified structure, small size, and ease of integration. Furthermore, this multi-mode photodetector possesses the ability to dynamically switch between multiple response modes. Under different operating scenarios, the detector can flexibly switch response modes according to actual needs, thereby achieving effective detection in various scenarios and breaking the limitation of traditional photodetectors that only have a single conductivity effect detection mode.

[0067] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A multi-mode photodetector, characterized in that, include: Substrate; A functional layer disposed on the substrate, the functional layer comprising a molybdenum disulfide material; Electrodes, which are disposed on the functional layer; The functional layer includes 1T phase molybdenum disulfide and 2H phase molybdenum disulfide, wherein the 1T phase molybdenum disulfide and the 2H phase molybdenum disulfide in the functional layer are mixed, and the functional layer includes a capacitor formed by van der Waals stacking of 1T phase molybdenum disulfide nanosheets and a heterojunction formed by the composite of 1T phase molybdenum disulfide and 2H phase molybdenum disulfide. The multi-mode photodetector has a conductivity detection mode when a bias voltage is applied, and a capacitance detection mode or a photovoltaic detection mode when no bias voltage is applied.

2. The multi-mode photodetector according to claim 1, characterized in that, When the thickness of the functional layer is less than 31 nm, the multi-mode photodetector has a capacitance detection mode when no bias voltage is applied, and the multi-mode photodetector has a conductivity detection mode when a bias voltage is applied.

3. The multi-mode photodetector according to claim 1, characterized in that, When the thickness of the functional layer is greater than or equal to 31 nm, the multi-mode photodetector has a photovoltaic detection mode when no bias voltage is applied, and the multi-mode photodetector has a conductivity detection mode when a bias voltage is applied.

4. A method for fabricating a multi-mode photodetector, characterized in that, include: Provide substrate; Electrochemical intercalation treatment of molybdenum disulfide raw material; Molybdenum disulfide raw material was used to prepare molybdenum disulfide nanosheet solution; The molybdenum disulfide nanosheets are coated onto the surface of the substrate, and a functional layer is formed on the surface of the substrate after drying. Electrodes are deposited on the functional layer to form a multimode photodetector.

5. The preparation method according to claim 4, characterized in that, The provision of the substrate includes: The substrate surface is subjected to a hydrophilic treatment.

6. The preparation method according to claim 4, characterized in that, The electrochemical intercalation treatment of molybdenum disulfide raw material includes: The bulk carbon material and molybdenum disulfide raw material are placed in the intercalating agent solution; A voltage is applied to the intercalating agent solution to electrochemically intercalate the molybdenum disulfide raw material, so that the molybdenum disulfide raw material has a 1T phase and a 2H phase.

7. The preparation method according to claim 6, characterized in that, The preparation of molybdenum disulfide nanosheet solution using the molybdenum disulfide raw material includes: The molybdenum disulfide raw material is pulverized to obtain molybdenum disulfide nanosheets; The molybdenum disulfide nanosheets are dispersed in an organic solvent to obtain a molybdenum disulfide nanosheet solution.

8. The preparation method according to claim 7, characterized in that, The intercalating agent solution is tetraheptylammonium bromide solution, and the organic solvent is isopropanol solution.

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