A method for preparing a plasma enhanced MoS2 photodetector

Abstract

The invention belongs to the technical field of photoelectric detectors for visible light communication, and specifically relates to a method for preparing a plasma enhanced MoS2 photoelectric detector, comprising the following steps: firstly, mechanically peeling off a MoS2 film from a bulk MoS2, transferring the film to a Si / SiO2 substrate, and coating a Cr / Au electrode on the MoS2 film by magnetron sputtering; coating a layer of Au film on the Si / SiO2 substrate by magnetron sputtering, and then subjecting the Au film to vacuum annealing at 600-800°C to form uniform Au nanoparticles; spin coating a PMMA film on the gold nanoparticles, removing SiO2, and then transferring the film to an Au electrode, removing PMMA, and thus obtaining a plasma MoS2 photoelectric detector; the method of the invention has the advantages of simple process and controllability, does not require a harsh growth environment, and is of great significance for realizing a high-sensitivity photoelectric detector device for visible light communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric detectors for visible light communication, and in particular relates to a method for preparing a plasma enhanced MoS2 photoelectric detector. Background Art

[0002] In recent years, visible light communication technology has been advancing rapidly, and the development of photodetectors has attracted great attention. A photodetector is a device that can convert optical signals into electrical signals. High-performance photodetectors play an important role in many areas of our daily lives, including optoelectronic displays, imaging, environmental monitoring, optical communications, military, security inspections, etc. At present, most of the photodetectors that are widely used in commercial applications are designed based on silicon materials. However, due to its indirect band gap characteristics, bulk silicon cannot effectively absorb and utilize light; in addition, its band gap of 1.1eV limits its application in the mid-to-far infrared and terahertz ranges. As one of the most competitive materials for designing photodetectors, two-dimensional materials have significant characteristics, including covering wavelengths from ultraviolet to terahertz wavelengths (terahertz, 10 12 Hz), ultrahigh photoresponsivity, polarization-sensitive photodetection, high-speed photoresponse, high spatial resolution imaging, etc. Photodetectors based on two-dimensional materials have attracted many research projects due to their unique structures and excellent electronic and optoelectronic properties.

[0003] As a typical semiconductor material, MoS2 has a band gap between 1.3-1.8eV and has the advantages of high carrier mobility, good chemical stability, and adjustable bandgap width with the number of layers. Therefore, it is a popular material for making photodetectors. However, at present, MoS2 photodetectors are mainly prepared by chemical vapor deposition technology, which is a complex process and the prepared MoS2 photodetectors have weak light absorption. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing a plasma enhanced MoS2 photodetector.

[0005] The present invention is specifically achieved through the following technical solutions.

[0006] A method for preparing a plasma enhanced MoS2 photodetector comprises the following steps:

[0007] S1. Preparation of devices containing electrode layers

[0008] Mechanically peeling off a MoS2 film from a bulk MoS2 and transferring it to a Si / SiO2 substrate; aligning the MoS2 film with a copper mesh, and sequentially coating a Cr electrode and an Au electrode on the MoS2 film by a magnetron sputtering coating device to obtain a device containing Cr / Au electrodes;

[0009] Preparation of Au nanoparticles

[0010] A layer of Au film is deposited on another Si / SiO2 substrate by magnetron sputtering, and then vacuum annealed at 600-800°C to form uniform Au nanoparticles on the Au film;

[0011] S2. Transfer of Au nanoparticles

[0012] A polymethyl methacrylate (PMMA) film is spin-coated on the Au nanoparticles and cured, and then the SiO2 layer is removed to obtain an Au / PMMA film, which is washed with water. The Au / PMMA film is then transferred to the Au electrode of the S1 device, and the PMMA layer is removed to obtain a plasma-enhanced MoS2 photodetector.

[0013] Preferably, in S1, the thickness of the MoS2 film is 20-50 nm.

[0014] Preferably, in S1, the thickness of the Cr electrode is 5 nm, and the thickness of the Au electrode is 50-100 nm.

[0015] Preferably, in S1, the Cr / Au electrode and the MoS2 film form an ohmic contact.

[0016] Preferably, in S1, the thickness of the Au film is 2-4 nm.

[0017] Preferably, in S2, the PMMA film is spin-coated with a PMMA ethyl lactate solution having a mass concentration of 15%.

[0018] Preferably, in S2, the SiO2 layer is etched away using a BOE solution, wherein the BOE solution is a mixed solution of hydrofluoric acid and ammonium fluoride in a mass ratio of 1:8.

[0019] Preferably, in S2, acetone is used to dissolve the PMMA layer.

[0020] Preferably, Si / SiO2 is used as a wafer substrate, the wafer substrate has a diameter of 2 inches, the SiO2 thickness is 300nm, and the Si thickness is 650μm.

[0021] Preferably, in S1, when preparing Au nanoparticles, the annealing time is 5-60 min.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention first mechanically peels off a MoS2 thin film from a bulk MoS2 and transfers it to a Si / SiO2 substrate, and then uses magnetron sputtering to plate a Cr / Au electrode on the MoS2 thin film; uses magnetron sputtering to plate a layer of Au thin film on the Si / SiO2 substrate, and then performs vacuum annealing at 600-800°C to form uniform Au nanoparticles from the Au thin film; spin-coats a PMMA thin film on the gold nanoparticles, removes SiO2, and then transfers it to the Au electrode, removes PMMA, and thus a plasma MoS2 photodetector can be obtained;

[0024] (2) The above method overcomes the problems of complex process and weak light absorption of the prepared materials in traditional chemical vapor deposition technology; the process is simple and controllable, does not require a harsh growth environment, and as the optical power of the prepared device increases, the current also increases, and the light absorption is enhanced, which is of great significance for the realization of high-sensitivity photodetector devices for visible light communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A longitudinal cross-sectional view of the plasma MoS2 photodetector provided by the present invention;

[0026] Figure 2 The Raman images are of MoS2 on SiO2 / Si substrate in Example 1 of the present invention and after Au nanoparticles of different thicknesses are transferred to MoS2 film (Au-MoS2) in Examples 1-3;

[0027] Figure 3 The current-voltage curve (532nm) of the plasma MoS2 photodetector prepared in Example 1 of the present invention under different light intensities. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0029] The experimental methods and detection methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0030] Example 1

[0031] This embodiment provides a method for preparing a plasma MoS2 photodetector, such as Figure 1 As shown, it includes, from bottom to top, a Si substrate layer 1, a SiO2 insulating layer 2, a MoS2 layer 3, a Cr electrode layer 4, a gold electrode layer 5 and a gold nanoparticle layer 6.

[0032] This embodiment also provides a preparation process of a plasma MoS2 photodetector, comprising the following steps:

[0033] (1) Mechanically exfoliate a MoS2 film from bulk MoS2 and transfer it to a Si / SiO2 substrate. The MoS2 film thickness is 25 nm, the substrate diameter is 2 inches, the SiO2 thickness is 300 nm, and the Si thickness is 650 μm.

[0034] (2) Aligning and attaching a 6 μW copper mesh on the MoS2 film in step (1);

[0035] (3) The MoS2 and copper mesh obtained in step (2) are coated with a layer of Cr / Au electrode by magnetron sputtering coating equipment to obtain a device containing an electrode layer, wherein the thickness of the Cr electrode is 5 nm and the thickness of the Au electrode is 50 nm.

[0036] Specific steps for preparing gold nanoparticles and transferring them:

[0037] (4) First, a 2 nm thick gold film is deposited on the Si / SiO2 substrate by magnetron sputtering;

[0038] (5) subjecting the gold film of step (4) to vacuum annealing at 700° C. for 15 min, so that the gold film forms uniform nanoparticles;

[0039] (6) Spin-coating a layer of PMMA film (15% PMMA ethyl lactate solution for spin-coating PMMA film) on the gold nanoparticles in step (5), and curing at 80° C. for 3 h;

[0040] (7) For the Au / PMMA layer on the Si / SiO2 substrate in step (6), the SiO2 layer is etched away using a BOE solution (the BOE solution is a mixed solution of hydrofluoric acid and ammonium fluoride in a mass ratio of 1:8), and the Au / PMMA film floats on the BOE solution;

[0041] (8) repeatedly washing the Au / PMMA film in step (7) with deionized water;

[0042] (9) The Au / PMMA film in step (8) is transferred to a MoS2 photodetector, and the PMMA layer is dissolved with acetone to obtain a plasma-enhanced MoS2 photodetector.

[0043] Example 2

[0044] This embodiment provides a method for preparing a plasma MoS2 photodetector, such as Figure 1 As shown, it includes, from bottom to top, a Si substrate layer 1, a SiO2 insulating layer 2, a MoS2 layer 3, a Cr electrode layer 4, a gold electrode layer 5 and a gold nanoparticle layer 6.

[0045] This embodiment also provides a preparation process of a plasma MoS2 photodetector, comprising the following steps:

[0046] (1) Mechanically exfoliate a MoS2 film from bulk MoS2 and transfer it to a Si / SiO2 substrate. The MoS2 film thickness is 20 nm, the substrate diameter is 2 inches, the SiO2 thickness is 300 nm, and the Si thickness is 650 μm.

[0047] (2) Aligning and attaching a 6 μW copper mesh on the MoS2 film in step (1);

[0048] (3) The MoS2 and copper mesh obtained in step (2) are coated with a layer of Cr / Au electrode by magnetron sputtering coating equipment to obtain a device containing an electrode layer, wherein the thickness of the Cr electrode is 5 nm and the thickness of the Au electrode is 50 nm.

[0049] Specific steps for preparing gold nanoparticles and transferring them:

[0050] (4) First, a 3 nm thick gold film is deposited on the Si / SiO2 substrate by magnetron sputtering;

[0051] (5) subjecting the gold film of step (4) to vacuum annealing at 700° C. for 15 min, so that the gold film forms uniform nanoparticles;

[0052] (6) Spin-coating a layer of PMMA film (15% PMMA ethyl lactate solution for spin-coating PMMA film) on the gold nanoparticles in step (5), and curing at 80° C. for 3 h;

[0053] (7) For the Au / PMMA layer on the Si / SiO2 substrate in step (6), the SiO2 layer is etched away using a BOE solution (the BOE solution is a mixed solution of hydrofluoric acid and ammonium fluoride in a mass ratio of 1:8), and the Au / PMMA film floats on the BOE solution;

[0054] (8) repeatedly washing the Au / PMMA film in step (7) with deionized water;

[0055] (9) The Au / PMMA film in step (8) is transferred to a MoS2 photodetector, and the PMMA layer is dissolved with acetone to obtain a plasma-enhanced MoS2 photodetector.

[0056] Example 3

[0057] This embodiment provides a method for preparing a plasma MoS2 photodetector, such as Figure 1 As shown, it includes, from bottom to top, a Si substrate layer 1, a SiO2 insulating layer 2, a MoS2 layer 3, a Cr electrode layer 4, a gold electrode layer 5 and a gold nanoparticle layer 6.

[0058] This embodiment also provides a preparation process of a plasma MoS2 photodetector, comprising the following steps:

[0059] (1) Mechanically exfoliate a MoS2 film from bulk MoS2 and transfer it to a Si / SiO2 substrate. The MoS2 film thickness is 50 nm, the substrate diameter is 2 inches, the SiO2 thickness is 300 nm, and the Si thickness is 650 μm.

[0060] (2) Aligning and attaching a 6 μW copper mesh on the MoS2 film in step (1);

[0061] (3) The MoS2 and copper mesh obtained in step (2) are coated with a layer of Cr / Au electrode by magnetron sputtering coating equipment to obtain a device containing an electrode layer, wherein the thickness of the Cr electrode is 5 nm and the thickness of the Au electrode is 50 nm.

[0062] Specific steps for preparing gold nanoparticles and transferring them:

[0063] (4) First, a 4 nm thick gold film is deposited on the Si / SiO2 substrate by magnetron sputtering;

[0064] (5) subjecting the gold film of step (4) to vacuum annealing at 700° C. for 15 min, so that the gold film forms uniform nanoparticles;

[0065] (6) Spin-coating a layer of PMMA film (15% PMMA ethyl lactate solution for spin-coating PMMA film) on the gold nanoparticles in step (5), and curing at 80° C. for 3 h;

[0066] (7) For the Au / PMMA layer on the Si / SiO2 substrate in step (6), the SiO2 layer is etched away using a BOE solution (the BOE solution is a mixed solution of hydrofluoric acid and ammonium fluoride in a mass ratio of 1:8), and the Au / PMMA film floats on the BOE solution;

[0067] (8) repeatedly washing the Au / PMMA film in step (7) with deionized water;

[0068] (9) The Au / PMMA film in step (8) is transferred to a MoS2 photodetector, and the PMMA layer is dissolved with acetone to obtain a plasma-enhanced MoS2 photodetector.

[0069] Figure 2 The Raman images of MoS2 on SiO2 / Si substrate of Example 1 of the present invention and Au-MoS2 in Examples 1-3; Figure 2It can be seen that there is no obvious change in the Raman peak when Au nanoparticles of different thicknesses are transferred to the MoS2 film, which proves that our method has no effect on the properties of the MoS2 film itself.

[0070] The plasma enhanced MoS2 photodetectors prepared in the above-mentioned embodiments 1-3 have similar performances. Hereinafter, the plasma enhanced MoS2 photodetector prepared in embodiment 1 will be taken as an example to test its relevant performances. Figure 3 The current-voltage curves (532nm) of the plasma MoS2 photodetector prepared in Example 1 of the present invention under different light intensities are shown in Table 1. Figure 3 It can be seen that as the light power increases, the current also increases. Through the above description, the MoS2 photodetector prepared by the method of the present invention has strong light absorption performance, and compared with the traditional chemical vapor deposition technology, the process is simple. This method has the advantages of simple process and controllability, and does not require a harsh growth environment. It is of great significance for realizing high-sensitivity photodetector devices for visible light communication.

[0071] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, they are also intended to be included.

Claims

1. A method for preparing a plasma enhanced MoS2 photodetector, characterized in that: The following steps are involved: S1. Preparation of Cr / Au electrode devices A MoS2 film is mechanically peeled off from a bulk MoS2 and transferred to a Si / SiO2 substrate; a copper mesh is covered on the MoS2 film, and a Cr electrode and an Au electrode are sequentially plated on the MoS2 film by magnetron sputtering to obtain a device containing Cr / Au electrodes; Preparation of Au nanoparticles A layer of Au film is deposited on another Si / SiO2 substrate by magnetron sputtering, and then annealed in vacuum at 600-800°C to obtain Au nanoparticles; S2. Transfer of Au nanoparticles A polymethyl methacrylate film is spin-coated on the Au nanoparticles and cured, and then the SiO2 layer is removed to obtain an Au / polymethyl methacrylate film, which is washed with water. Then, the Au / polymethyl methacrylate film is transferred to the Au electrode of the S1 device, and the polymethyl methacrylate layer is removed to obtain a plasma-enhanced MoS2 photodetector.

2. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S1, the thickness of MoS2 film is 20-50nm.

3. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S1, the thickness of the Cr electrode is 5 nm, and the thickness of the Au electrode is 50-100 nm.

4. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S1, the Cr / Au electrode and the MoS2 film form an ohmic contact.

5. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S1, the thickness of the Au film is 2-4 nm.

6. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S2, when spin coating the polymethyl methacrylate film, a polymethyl methacrylate ethyl lactate solution with a mass concentration of 15% is used.

7. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S2, the SiO2 layer is etched away using a BOE solution, which is a mixed solution of hydrofluoric acid and ammonium fluoride in a mass ratio of 1:

8.

8. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S2, acetone is used to dissolve away the polymethyl methacrylate layer.

9. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: The Si / SiO2 in S1 are both wafer substrates, the wafer substrate has a diameter of 2 inches, the SiO2 thickness is 300nm, and the Si thickness is 650μm.

10. The method for preparing a plasma enhanced MoS2 photodetector according to claim 1, characterized in that: In S1, when preparing Au nanoparticles, the annealing time is 5-60 min.

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