Atomic-scale patterning in two-dimensional van der Waals superlattices
Atomic-scale patterning in two-dimensional van der Waals superlattices
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DOI：
10.1088/1361-6528/ab596c
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发表时间：
2020-03-06
期刊：
影响因子：
3.5
通讯作者：
Drndic, Marija
中科院分区：
文献类型：
--
作者：
Das, Paul Masih;Thiruraman, Jothi Priyanka;Drndic, Marija
由两种堆叠单层材料组成的二维（2D）范德华超晶格作为新型光电和结构行为的平台引起了人们的极大兴趣。尽管研究主要集中在超晶格制造上，但对这些系统的纳米级图案化和结构修饰的研究较少。在本报告中，我们使用像差校正扫描透射电子显微镜（STEM）展示了二维超晶格中纳米孔/缺陷的局部逐层减薄和形成，例如堆叠的MoS2-WS2范德华异质结构和化学气相沉积双层WSe2。受控电子束照射用于通过去除底层原子来局部减薄超晶格，然后通过烧蚀第二层原子来形成缺陷。由此产生的缺陷表现出原子级锐利的孔边缘，可调直径低至 0.6 nm。结构周期性和聚焦 STEM 辐射也被用来在具有不同扭转角和可通约性的超晶格中形成密堆积纳米孔阵列。应用这些方法和机制为堆叠二维纳米器件的原子级图案化提供了一种前向方法。
Two-dimensional (2D) van der Waals superlattices comprised of two stacked monolayer materials have attracted significant interest as platforms for novel optoelectronic and structural behavior. Although studies are focused on superlattice fabrication, less effort has been given to the nanoscale patterning and structural modification of these systems. In this report, we demonstrate the localized layer-by-layer thinning and formation of nanopores/defects in 2D superlattices, such as stacked MoS2-WS2 van der Waals heterostructures and chemical vapor deposited bilayer WSe2, using aberration-corrected scanning transmission electron microscopy (STEM). Controlled electron beam irradiation is used to locally thin superlattices by removing the bottom layer of atoms, followed by defect formation through ablation of the second layer of atoms. The resulting defects exhibit atomically-sharp pore edges with tunable diameters down to 0.6 nm. Structural periodicities and focused STEM irradiation are also utilized to form close-packed nanopore arrays in superlattices with varying twist angles and commensurability. Applying these methods and mechanisms provides a forward approach in the atomic-scale patterning of stacked 2D nanodevices.