Hunan Key Laboratory of Two-Dimensional Materials, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China.
Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA.
Nature. 2021 Mar;591(7850):385-390. doi: 10.1038/s41586-021-03338-0. Epub 2021 Mar 17.
Two-dimensional (2D) materials and the associated van der Waals (vdW) heterostructures have provided great flexibility for integrating distinct atomic layers beyond the traditional limits of lattice-matching requirements, through layer-by-layer mechanical restacking or sequential synthesis. However, the 2D vdW heterostructures explored so far have been usually limited to relatively simple heterostructures with a small number of blocks. The preparation of high-order vdW superlattices with larger number of alternating units is exponentially more difficult, owing to the limited yield and material damage associated with each sequential restacking or synthesis step. Here we report a straightforward approach to realizing high-order vdW superlattices by rolling up vdW heterostructures. We show that a capillary-force-driven rolling-up process can be used to delaminate synthetic SnS/WSe vdW heterostructures from the growth substrate and produce SnS/WSe roll-ups with alternating monolayers of WSe and SnS, thus forming high-order SnS/WSe vdW superlattices. The formation of these superlattices modulates the electronic band structure and the dimensionality, resulting in a transition of the transport characteristics from semiconducting to metallic, from 2D to one-dimensional (1D), with an angle-dependent linear magnetoresistance. This strategy can be extended to create diverse 2D/2D vdW superlattices, more complex 2D/2D/2D vdW superlattices, and beyond-2D materials, including three-dimensional (3D) thin-film materials and 1D nanowires, to generate mixed-dimensional vdW superlattices, such as 3D/2D, 3D/2D/2D, 1D/2D and 1D/3D/2D vdW superlattices. This study demonstrates a general approach to producing high-order vdW superlattices with widely variable material compositions, dimensions, chirality and topology, and defines a rich material platform for both fundamental studies and technological applications.
二维(2D)材料和相关的范德华(vdW)异质结构通过逐层机械堆叠或顺序合成,为整合超出传统晶格匹配要求的独特原子层提供了极大的灵活性。然而,迄今为止探索的 2D vdW 异质结构通常仅限于具有少量块的相对简单的异质结构。由于与每个顺序堆叠或合成步骤相关的有限产量和材料损坏,制备具有更大数量交替单元的高阶 vdW 超晶格的难度呈指数级增加。在这里,我们报告了一种通过卷起 vdW 异质结构来实现高阶 vdW 超晶格的简单方法。我们表明,毛细力驱动的卷起过程可用于从生长衬底上剥离合成的 SnS/WSe vdW 异质结构,并产生具有交替的 WSe 和 SnS 单层的 SnS/WSe 卷起物,从而形成高阶 SnS/WSe vdW 超晶格。这些超晶格的形成调制了电子能带结构和维度,导致从半导体到金属、从 2D 到一维(1D)的传输特性转变,具有角度相关的线性磁阻。该策略可扩展到创建各种 2D/2D vdW 超晶格、更复杂的 2D/2D/2D vdW 超晶格以及超越二维材料,包括三维(3D)薄膜材料和一维纳米线,以产生混合维度 vdW 超晶格,例如 3D/2D、3D/2D/2D、1D/2D 和 1D/3D/2D vdW 超晶格。该研究展示了一种通用方法来制备具有广泛变化的材料组成、尺寸、手性和拓扑结构的高阶 vdW 超晶格,并为基础研究和技术应用定义了一个丰富的材料平台。