Observing Imperfection in Atomic Interfaces for van der Waals Heterostructures

• DOI: 10.1021/acs.nanolett.7b01248
• Publication Date: 2017-07-25T14:46:12Z
• Authors: Aidan. P. Rooney; Aleksey Kozikov; Alexander N. Rudenko; Eric Prestat; Matthew J. Hamer; Freddie Withers; Yang Cao; Kostya S. Novoselov; Mikhail I. Katsne...; Roman Gorbachev; Sarah J. Haigh
• Keywords: Exfoliation joint

Vertically stacked van der Waals heterostructures are a lucrative platform for exploring the rich electronic and optoelectronic phenomena in two-dimensional materials. Their performance will be strongly affected by impurities defects at interfaces. Here we present first systematic study of interfaces heterostructure using cross sectional scanning transmission electron microscope (STEM) imaging. By measuring interlayer separations comparing these to density functional theory (DFT) calculations find that pristine exist between hBN MoS2 or WS2 stacks prepared mechanical exfoliation air. However, two technologically important transition metal dichalcogenide (TMDC) systems, MoSe2 WSe2, our measurement provide evidence impurity species being trapped buried with hBN: which flat nanometer length scale. While decreasing thickness encapsulated WSe2 from bulk monolayer see increase separation. We attribute differences thinnest TMDC flakes flexible hence able deform mechanically around sparse population protruding interfacial impurities. show air sensitive dimensional (2D) crystal NbSe2 can fabricated into processing an inert-gas environment. Finally adopting glove-box transfer significantly improves quality compared