Preparation method of corner two-dimensional material with high uniformity and controllable multiple distortion angles

Abstract

The invention discloses a preparation method and application of a corner two-dimensional material with high uniformity and multiple controllable distortion angles. The preparation method comprises the following steps: obtaining a single-layer two-dimensional material on a hydrophilic substrate and cutting the single-layer two-dimensional material into several parts; a PPC film is spin-coated, several adjacent rectangles with parallel edges are cut on the PPC film by using laser, a plurality of PPC rectangles are formed by mechanically stripping the redundant PPC film on the periphery, each PPC rectangle covers a part of the single-layer two-dimensional material, and the distortion angle between every two adjacent PPC rectangles is equal to the distortion angle between every two adjacent parts of the two-dimensional material; the PPC rectangles are sequentially picked up from the substrate one by one through PDMS, the PPC rectangles are sequentially stacked according to the edge control distortion angles of the PPC rectangles, PPC is removed, and preparation of the corner two-dimensional material with the multiple controllable distortion angles can be achieved. The method is wide in application range and high in efficiency, and the prepared corner graphene has highly uniform distortion angle distribution, so that the corner graphene has great advantages in the field of corner electronics.

Description

Technical Field

[0001] This invention belongs to the fields of two-dimensional materials and twisted electronics, and relates to a method and supporting apparatus for preparing twisted graphene with high uniformity and controllable twist angle. Background Technology

[0002] Layered two-dimensional materials such as graphene possess highly tunable electrical and optical properties, and are widely used in the design and fabrication of novel electronic and optoelectronic devices. Since the discovery of Mott insulating states and unconventional superconductivity in 1.1° twisted bilayer graphene, twisted bilayer homogeneous structures based on monolayer two-dimensional materials have attracted widespread attention.

[0003] However, fabricating twisted two-dimensional materials is extremely complex, requiring precise control of the twist angle. Furthermore, the stability of the twist angle is crucial, as even a minute change of 0.1° can lead to significant alterations in the band structure of the twisted two-dimensional material. Current fabrication techniques generally produce low-quality twisted two-dimensional materials, exhibiting problems such as sample defects, uncontrollable twist angles, large-scale spatial fluctuations in the twist angle distribution, or surface coatings with boron nitride. Therefore, there is an urgent need for a method capable of fabricating high-quality twisted two-dimensional materials with controllable twist angles. Summary of the Invention

[0004] The purpose of this invention is to provide a technical route for preparing two-dimensional twisted materials with high uniformity and controllable twist angles.

[0005] To achieve the above objectives, the steps of the method described in this invention are as follows: The first step is to treat the initial substrate with oxygen plasma to make it hydrophilic, and then use mechanical exfoliation to prepare high-quality monolayer two-dimensional materials on the initial substrate. The second step involves using laser cutting to pattern a single-layer two-dimensional material. The target corner two-dimensional material needs to be divided into several parts to achieve the desired number of layers. The third step involves spin-coating a PPC polymer layer onto a single-layer two-dimensional material, and then using a laser to cut out several closely adjacent rectangular patterns on the PPC film according to the patterned two-dimensional material. After mechanically peeling off the surrounding useless PPC film, several rectangular PPC patterns remain. The fourth step involved fabricating a rectangular protrusion structure on a silicon wafer and then preparing PDMS with shallow grooves on the surface using a casting process. The fifth step involves generating water droplets on the substrate surface using ultrasonic water spray, allowing water molecules to penetrate between the PPC and the substrate, thereby achieving their separation. In the sixth step, only the PPC rectangles in contact with PDMS can be picked up from the substrate. By utilizing the shallow grooves on the PDMS surface, each rectangular PPC and its covering monolayer 2D material can be picked up individually, forming multiple PDMS / PPC / monolayer 2D material structures. At this point, the included angle between the edges of the PPCs is the twist angle between the graphene layers. Step 7 involves releasing PPC / monolayer 2D material onto the target substrate, followed by dissolving the PPC. By repeating this process, multiple monolayer materials are stacked together to form a corner 2D material, with the interlayer twist angle controlled by the edges of the PPC. Attached Figure Description

[0006] Figure 1 PDMS with shallow grooves on the surface; Figure 2 Schematic diagram of the fabrication process of corner-shaped two-dimensional materials; Figure 3 Angular bilayer graphene with different twist angles; Figure 4 Four layers of graphene with a continuous 12-degree twist at the corner; Figure 5 Atomic-resolution images and selected area electron diffraction images of bilayer graphene with different twist angles; Detailed Implementation

[0007] To further illustrate the present invention, the corner two-dimensional material preparation technology provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but this should not be construed as limiting the scope of protection of the present invention. The materials and instruments used in the following embodiments are all commercially available. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the method of the present invention. Example

[0008] Preparation of PDMS with shallow grooves on the surface First, a rectangular protrusion microstructure was created on the silicon wafer using photolithography and etching. Figure 1 (a) shows an optical micrograph of one of the microstructures. These microstructures are approximately 200 micrometers wide and 10 micrometers high, such as... Figure 1 As shown in (b), a mixed solution of Sylgard 184 silicon substrate and curing agent was prepared at a ratio of 10:1, then poured onto a silicon wafer, and the entire device was baked at 55°C for 24 hours. Finally, the PDMS film was manually peeled off, resulting in a shallow trench approximately 10 micrometers deep on the PDMS surface, as shown in [image / description]. Figure 1 As shown in (c). Example

[0009] Preparation of twisted graphene The preparation process diagram is as follows: Figure 2 As shown, firstly, high-quality monolayer graphene was peeled from natural graphite crystals onto a SiO2 / Si substrate using Scotch tape. Under a 100x objective lens, it was directly cut into several parts using a femtosecond laser. Next, a PPC film was spin-coated onto the substrate surface, and then a corresponding number of rectangles were cut into the PPC film using a femtosecond laser, ensuring that each graphene part was covered by one rectangle. Scotch tape was used to peel off the outer PPC film from one side of the substrate, ultimately forming a PPC rectangle / graphene structure. After spraying water droplets onto the substrate surface, water molecules entered between the PPC rectangles and the substrate, separating the PPC rectangles / graphene. Using the shallow grooves on the PDMS surface, each PPC rectangle / graphene structure was extracted individually. At this point, the twist angle between the PPCs was the same as the twist angle between each graphene part. Based on this, each PPC / graphene structure was sequentially stacked on the target substrate, and the PPC was dissolved in chloroform, ultimately forming a twisted graphene structure. Figure 3 and Figure 4 The corner bilayer and quadrilayer graphene structures established using this method are shown respectively. Example

[0010] Transmission electron microscopy test of twisted graphene like Figure 5 As shown, this method was used to fabricate bilayer graphene with twist angles of 10°, 20°, and 30° on a dedicated grid for transmission electron microscopy. With spherical aberration correction, the moiré pattern formed by the angular distortion could be directly observed. Furthermore, selected area electron diffraction (SED) analysis confirmed that the difference between the actual and preset twist angles was less than 0.5°, and the fluctuation of the twist angle within the same sample was less than 0.1°, demonstrating that this method can fabricate uniformly twisted graphene.

Claims

1. A method for preparing a two-dimensional twisted material with high uniformity and multiple controllable twist angles, characterized in that, The method includes the following steps: a) Obtain a single-layer two-dimensional material on a hydrophilic substrate, and cut the single-layer two-dimensional material into multiple parts; b) Spin-coating a PPC film onto the single-layer two-dimensional material, and using a laser to cut out several adjacent rectangular regions with parallel edges on the PPC film; c) Remove excess portions of the PPC film by mechanical peeling, thereby forming multiple PPC rectangles in each rectangular region, the PPC rectangles covering each cut portion of the monolayer two-dimensional material, wherein the relative twist angle between the PPC rectangles is equal to the twist angle between the cut portions of the monolayer two-dimensional material; d) Use PDMS to pick up the PPC rectangles one by one; e) Control the twist angle according to the edge of the PPC rectangle, stack the PPC rectangles in sequence and dissolve them to obtain a two-dimensional material with multiple controllable twist angles.

2. The method for preparing a two-dimensional twisted material with high uniformity and multiple controllable twist angles according to claim 1, characterized in that, The prepared two-dimensional twisted materials are not limited to graphene; other two-dimensional twisted materials such as twisted molybdenum disulfide and twisted boron nitride can also be prepared using this technology.

3. The method for preparing a two-dimensional material with high uniformity and multiple controllable twist angles according to claim 1, characterized in that, The available transfer media are not limited to PPC; other common polymers, such as PMMA and PC, are also suitable for this technology.

4. The method for preparing a two-dimensional material with high uniformity and multiple controllable twist angles according to claim 1, characterized in that, The prepared two-dimensional twisted material can have any number of controllable twist angles, depending on the actual needs.

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