A method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting

Abstract

The present invention discloses a method for preparing a two-dimensional layered bismuth selenide nanosheet based on nanoimprinting, wherein the bismuth selenide sheet is attached to a substrate using polydimethylsiloxane, and then the whole is placed on a workbench of a nanoimprinter, and imprinted at a temperature not higher than 80°C and a pressure of 20 to 30 bar to obtain a bismuth selenide nanosheet. The present invention peels off a bismuth selenide material with strong interlayer bonding strength through nanoimprinting, and uses a substrate with good bonding strength with the bismuth selenide material to promote the separation of thick bismuth selenide sheets below the thermal release temperature of polydimethylsiloxane and in a stable pressure atmosphere, thereby obtaining a bismuth selenide sheet with a thickness of more than ten nanometers.

Description

Technical Field

[0001] The invention relates to a method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting. Background Art

[0002] Since the first discovery of graphene in 2004, there has been an increasing amount of research on two-dimensional materials. The continuous improvement of two-dimensional material preparation technology and the processing of atomic-level materials have greatly promoted the development of two-dimensional materials and two-dimensional devices. Two-dimensional materials are also widely used in electronics, optoelectronics, topological spin electronics, bio-application energy storage and energy conversion devices, etc. Tape mechanical exfoliation is a common method for preparing two-dimensional materials, but this method has problems such as low yield and small lateral size of the exfoliated samples. When facing layered materials with strong binding energy such as bismuth selenide, the efficiency of preparing two-dimensional layered bismuth selenide by tape mechanical exfoliation will be further reduced, and two-dimensional layered bismuth selenide with a thickness of more than ten nanometers cannot be obtained. Nanoimprinting, as a method of micro-nano processing, is one of the alternatives to photolithography. It can prepare arrayed structures on a large scale and has the advantages of low cost, high throughput, and high resolution. Summary of the invention

[0003] Technical problem: The purpose of the present invention is to provide a method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting, which can significantly improve the preparation efficiency of bismuth selenide nanosheets, that is, multiple samples can be prepared on a sample table at the same time and bismuth selenide nanosheets with a thickness of more than ten nanometers can be obtained on the substrate.

[0004] Technical solution: The method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting described in the present invention is: using polydimethylsiloxane to attach the bismuth selenide sheet to the substrate, and then placing the entire sheet on the workbench of a nanoimprinter, and imprinting at no more than 80°C and at a pressure of 20 to 30 bar to obtain the bismuth selenide nanosheets.

[0005] Among them, the process of using polydimethylsiloxane to attach the bismuth selenide sheet to the substrate is specifically as follows: use tape to adhere the bismuth selenide block to obtain a tape with a thick bismuth selenide sheet; laminate the side of the tape with the thick bismuth selenide sheet to polydimethylsiloxane, and after laminating, separate the tape and polydimethylsiloxane, and partially transfer the thick bismuth selenide sheet on the tape to the polydimethylsiloxane to obtain polydimethylsiloxane with the bismuth selenide sheet adhered to it; laminate the side of the polydimethylsiloxane with the bismuth selenide sheet adhered to the substrate to attach the bismuth selenide sheet to the substrate.

[0006] Wherein, the thickness of the bismuth selenide sheet on the polydimethylsiloxane is 10 to 60 μm.

[0007] Wherein, the bonding time of the adhesive tape and polydimethylsiloxane is 2 to 10 minutes.

[0008] The substrate is a silicon wafer substrate with a silicon oxide layer or an aluminum oxide layer, the CZ silicon wafer is single-polished and double-oxidized P / 100, the silicon oxide layer is 300nm thick, and the aluminum oxide layer is deposited on the surface of the silicon wafer by an atomic layer deposition system, with a thickness of 30nm.

[0009] Wherein, the thickness of the bismuth selenide nanosheet is 10-19 nm.

[0010] Wherein, the stamping time is 60s to 120s.

[0011] The silicon wafer substrate with a silicon oxide layer or an aluminum oxide layer has high binding energy with the bismuth selenide material (the higher the binding energy obtained by subtracting the surface energy of both from the adhesion energy, the easier it is to produce a bismuth selenide sheet with a low nanometer thickness). Nanoimprinting provides stable temperature and pressure, and the peeling of two-dimensional layered bismuth selenide is achieved at a temperature lower than the thermal release temperature of polydimethylsiloxane (80°C) (when it is higher than 80°C, polydimethylsiloxane has no adhesion with bismuth selenide, which is not conducive to the peeling of bismuth selenide nanosheets. When the temperature is between 50 and 70°C, the adhesion between polydimethylsiloxane and bismuth selenide is weakened, which is conducive to the peeling of bismuth selenide nanosheets).

[0012] Beneficial effects: The present invention uses nanoimprinting to peel off bismuth selenide materials with strong interlayer bonding strength, adopts a substrate with good bonding strength with the bismuth selenide material, and promotes the separation between thick bismuth selenide layers below the thermal release temperature of polydimethylsiloxane and in a stable pressure atmosphere, thereby obtaining a bismuth selenide sheet with a thickness of more than ten nanometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a flow chart of the method for preparing bismuth selenide nanosheets of the present invention;

[0014] Figure 2 This is the Raman spectrum of the bismuth selenide nanosheets prepared in Example 1;

[0015] Figure 3 The atomic force microscope image and thickness of the bismuth selenide nanosheet prepared in Example 1;

[0016] Figure 4 This is the Raman spectrum of the bismuth selenide nanosheets prepared in Example 2;

[0017] Figure 5 The atomic force microscope image and thickness of the bismuth selenide nanosheet prepared in Example 2;

[0018] Figure 6 This is the Raman spectrum of the bismuth selenide nanosheets prepared in Example 3;

[0019] Figure 7The atomic force microscope image and thickness of the bismuth selenide nanosheet prepared in Example 3;

[0020] Figure 8 This is the Raman spectrum of the bismuth selenide nanosheets prepared in Example 4;

[0021] Fig. 9 The atomic force microscope image and thickness of the bismuth selenide nanosheet prepared in Example 4. DETAILED DESCRIPTION

[0022] Example 1

[0023] like Figure 1 As shown, the method for preparing bismuth selenide nanosheets of the present invention comprises the following steps:

[0024] (1) Using tape to adhere the bismuth selenide block, after separation, obtain a tape with a bismuth selenide thick sheet; taking polydimethylsiloxane of a suitable size to the substrate, laminating the side of the tape with the bismuth selenide thick sheet with the polydimethylsiloxane, after laminating for 2 minutes, separating the tape and the polydimethylsiloxane, and transferring the bismuth selenide thick sheet on the tape to the polydimethylsiloxane to obtain a polydimethylsiloxane with a bismuth selenide sheet adhered thereto; taking a clean silicon wafer with a silicon oxide layer, and placing the side of the polydimethylsiloxane with the bismuth selenide sheet adhered thereto tightly on the silicon wafer substrate, so that the bismuth selenide sheet adheres to the silicon wafer substrate; placing the whole thing on the sample stage of the nanoimprint machine;

[0025] (2) Adjust the stamping temperature to 50°C, the pressure to 20 bar, and the stamping time to 60 s;

[0026] (3) After the experiment is completed and the temperature is cooled to room temperature, a silicon wafer substrate with layered bismuth selenide nanosheets is obtained.

[0027] The obtained bismuth selenide nanosheets were characterized by spectroscopy using a confocal Raman microscope. The test results are as follows: Figure 2 As shown in Figure 2, the phase characterization results show that there is no obvious difference between the Raman peak of the nanosheet and the Raman peak of the bismuth selenide bulk. The morphology and thickness of the bismuth selenide nanosheet were characterized by atomic force microscopy. The surface of the layered material is flat and the thickness is 19.10nm. The test results are shown in Figure 2. Figure 3 shown.

[0028] Example 2

[0029] The method for preparing bismuth selenide nanosheets of the present invention comprises the following steps:

[0030] (1) Using tape to adhere the bismuth selenide block, after separation, obtain a tape with a bismuth selenide thick sheet; taking polydimethylsiloxane of a suitable size to the substrate, laminating the side of the tape with the bismuth selenide thick sheet with the polydimethylsiloxane, after laminating for 10 minutes, separating the tape and the polydimethylsiloxane, and transferring the bismuth selenide thick sheet on the tape to the polydimethylsiloxane to obtain a polydimethylsiloxane with a bismuth selenide sheet adhered thereto; taking a clean silicon wafer with a silicon oxide layer, and placing the side of the polydimethylsiloxane with the bismuth selenide sheet adhered thereto tightly on the silicon wafer substrate, so that the bismuth selenide sheet adheres to the silicon wafer substrate; placing the whole thing on the sample stage of the nanoimprint machine;

[0031] (2) Adjust the stamping temperature to 70°C, the pressure to 20 bar, and the stamping time to 120 s;

[0032] (3) After the experiment is completed and the temperature is cooled to room temperature, a silicon wafer substrate with layered bismuth selenide nanosheets is obtained.

[0033] The obtained bismuth selenide nanosheets were characterized by spectroscopy using a confocal Raman microscope. The test results are as follows: Figure 4 As shown in the figure, the phase characterization results show that there is no obvious difference between the Raman peak of the nanosheet and the Raman peak of the bismuth selenide bulk. The morphology and thickness of the bismuth selenide nanosheet were characterized by atomic force microscopy. The surface of the layered material is flat and the thickness is 9.98nm. The test results are as follows Figure 5 shown.

[0034] Example 3

[0035] The method for preparing bismuth selenide nanosheets of the present invention comprises the following steps:

[0036] (1) Using tape to adhere the bismuth selenide block, after separation, obtain a tape with a bismuth selenide thick sheet; taking polydimethylsiloxane of a suitable size to the substrate, laminating the side of the tape with the bismuth selenide thick sheet with the polydimethylsiloxane, after laminating for 2 minutes, separating the tape and the polydimethylsiloxane, and transferring the bismuth selenide thick sheet on the tape to the polydimethylsiloxane to obtain a polydimethylsiloxane with a bismuth selenide sheet adhered thereto; taking a clean silicon wafer with an aluminum oxide layer, and placing the side of the polydimethylsiloxane with the bismuth selenide sheet adhered thereto tightly on the silicon wafer substrate, so that the bismuth selenide sheet adheres to the silicon wafer substrate; placing the whole thing on the sample stage of the nanoimprint machine;

[0037] (2) Adjust the stamping temperature to 50°C, the pressure to 20 bar, and the stamping time to 60 s;

[0038] (3) After the experiment is completed and the temperature is cooled to room temperature, a silicon wafer substrate with layered bismuth selenide nanosheets is obtained.

[0039] The obtained bismuth selenide nanosheets were characterized by spectroscopy using a confocal Raman microscope. The test results are as follows: Figure 6As shown in Figure 2, the phase characterization results show that there is no significant difference between the Raman peak of the nanosheet and the Raman peak of the bismuth selenide bulk. The morphology and thickness of the bismuth selenide nanosheet were characterized by atomic force microscopy. The surface of the layered material is flat and the thickness is 17.67nm. The test results are shown in Figure 2. Figure 7 shown.

[0040] Example 4

[0041] The method for preparing bismuth selenide nanosheets of the present invention comprises the following steps:

[0042] (1) Using tape to adhere the bismuth selenide block, after separation, obtain a tape with a bismuth selenide thick sheet; taking polydimethylsiloxane of a suitable size to the substrate, laminating the side of the tape with the bismuth selenide thick sheet with the polydimethylsiloxane, after laminating for 10 minutes, separating the tape and the polydimethylsiloxane, and transferring the bismuth selenide thick sheet on the tape to the polydimethylsiloxane to obtain a polydimethylsiloxane with a bismuth selenide sheet adhered thereto; taking a clean silicon wafer with an aluminum oxide layer, and placing the side of the polydimethylsiloxane with the bismuth selenide sheet adhered thereto tightly on the silicon wafer substrate, so that the bismuth selenide sheet adheres to the silicon wafer substrate; placing the whole thing on the sample stage of the nanoimprint machine;

[0043] (2) Adjust the stamping temperature to 70°C, the pressure to 20 bar, and the stamping time to 120 s;

[0044] (3) After the experiment is completed and the temperature is cooled to room temperature, a silicon wafer substrate with layered bismuth selenide nanosheets is obtained.

[0045] The obtained bismuth selenide nanosheets were characterized by spectroscopy using a confocal Raman microscope. The test results are as follows: Figure 8 As shown in Figure 2, the phase characterization results show that there is no obvious difference between the Raman peak of the nanosheet and the Raman peak of the bismuth selenide bulk. The morphology and thickness of the bismuth selenide nanosheet were characterized by atomic force microscopy. The surface of the layered material is flat and the thickness is 14.38nm. The test results are shown in Figure 2. Fig. 9 shown.

[0046] Examples 1 to 4 show that by controlling the imprint temperature at 50°C-70°C and the pressure at 20 bar, bismuth selenide nanosheets with a thickness of more than ten nanometers can be obtained. For the same substrate, the increase in temperature further reduces the thickness of the sheet. The nanosheet layer obtained on each substrate under the conditions of temperature 70°C and pressure 20 bar is thinner. This change trend is more obvious on the silicon oxide substrate than on the aluminum oxide substrate. For different substrates, the effect of temperature change on the sheet thickness is not the relationship that the temperature increases and the sheet thickness becomes thinner, which is related to the characteristics of the substrate itself.

[0047] Comparative Example 1

[0048] The method for preparing bismuth selenide nanosheets of the present invention comprises the following steps:

[0049] (1) Using tape to adhere the bismuth selenide block, after separation, obtain a tape with a bismuth selenide thick sheet; taking polydimethylsiloxane of a suitable size to the substrate, laminating the side of the tape with the bismuth selenide thick sheet with the polydimethylsiloxane, after laminating for 10 minutes, separating the tape and the polydimethylsiloxane, and transferring the bismuth selenide thick sheet on the tape to the polydimethylsiloxane to obtain a polydimethylsiloxane with a bismuth selenide sheet adhered thereto; taking a clean silicon wafer with a silicon oxide layer, and placing the side of the polydimethylsiloxane with the bismuth selenide sheet adhered thereto tightly on the silicon wafer substrate, so that the bismuth selenide sheet adheres to the silicon wafer substrate; placing the whole thing on the sample stage of the nanoimprint machine;

[0050] (2) Adjust the stamping temperature to 90°C, the pressure to 20 bar, and the stamping time to 120 s;

[0051] (3) After the experiment is completed and the temperature is cooled to room temperature, a silicon wafer substrate with layered bismuth selenide nanosheets is obtained.

[0052] The morphology and thickness of bismuth selenide nanosheets were characterized using atomic force microscopy. The surface of the layered material was flat and the thickness was 83.55nm.

[0053] Comparative Example 2

[0054] The method for preparing bismuth selenide nanosheets of the present invention comprises the following steps:

[0055] (1) Using tape to adhere the bismuth selenide block, after separation, obtain a tape with a bismuth selenide thick sheet; taking polydimethylsiloxane of a suitable size to the substrate, laminating the side of the tape with the bismuth selenide thick sheet with the polydimethylsiloxane, after laminating for 10 minutes, separating the tape and the polydimethylsiloxane, and transferring the bismuth selenide thick sheet on the tape to the polydimethylsiloxane to obtain a polydimethylsiloxane with a bismuth selenide sheet adhered thereto; taking a clean silicon wafer with a silicon oxide layer, and placing the side of the polydimethylsiloxane with the bismuth selenide sheet adhered thereto tightly on the silicon wafer substrate, so that the bismuth selenide sheet adheres to the silicon wafer substrate; placing the whole thing on the sample stage of the nanoimprint machine;

[0056] (2) Adjust the stamping temperature to 70°C, the pressure to 30 bar, and the stamping time to 120 s;

[0057] (3) After the experiment is completed and the temperature is cooled to room temperature, a silicon wafer substrate with layered bismuth selenide nanosheets is obtained.

[0058] The morphology and thickness of bismuth selenide nanosheets were characterized using atomic force microscopy. The surface of the layered material was flat and the thickness was 37.93nm.

[0059] Comparative Examples 1 to 2 show that when the temperature exceeds 70° C. or the imprint pressure is higher than 20 bar, the bonding force between the thick bismuth selenide sheet and the polydimethylsiloxane is weakened, resulting in a rapid increase in the thickness of the nanosheet on the substrate.

Claims

1. A method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting, characterized in that: The method comprises: using polydimethylsiloxane to attach a bismuth selenide sheet to a substrate, and then placing the entire sheet on a workbench of a nanoimprinter, and performing imprinting at a temperature below 70° C. and a pressure of 20 bar to obtain a bismuth selenide nanosheet; The process of using polydimethylsiloxane to attach the bismuth selenide sheet to the substrate is specifically as follows: using tape to adhere the bismuth selenide block to obtain a tape with a thick bismuth selenide sheet; laminating the side of the tape with the thick bismuth selenide sheet to the polydimethylsiloxane, and after laminating, separating the tape and the polydimethylsiloxane, and partially transferring the thick bismuth selenide sheet on the tape to the polydimethylsiloxane to obtain polydimethylsiloxane with the bismuth selenide sheet adhered to it; laminating the side of the polydimethylsiloxane with the bismuth selenide sheet adhered to the substrate to attach the bismuth selenide sheet to the substrate; the substrate is a silicon wafer substrate with a silicon oxide layer or an aluminum oxide layer.

2. The method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting according to claim 1, characterized in that: The thickness of the bismuth selenide sheet on the polydimethylsiloxane is 10-60 μm.

3. The method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting according to claim 1, characterized in that: The bonding time of the adhesive tape and polydimethylsiloxane is 2 to 10 minutes.

4. The method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting according to claim 1, characterized in that: The substrate is a silicon wafer substrate with a silicon oxide layer or an aluminum oxide layer.

5. The method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting according to claim 1, characterized in that: The thickness of the bismuth selenide nanosheet is 10-19 nm.

6. The method for preparing two-dimensional layered bismuth selenide nanosheets based on nanoimprinting according to claim 1, characterized in that: The stamping time is 60s~120s.

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