Probing atomic reconstruction at 2D interfaces via scanning transmission electron microscopy

Scanning transmission electron microscopy (STEM) provides uniquely powerful tools to study the interfacial structure and interactions of 2D materials up to atomic precision. In my talk, I will discuss how we create and utilize 2D multilayer stacks to create nanoscale laboratories for studying the atomic structure, structural transformations, and properties of 2D interfaces inside the STEM. For example, we utilize graphene encapsulation in combination with a MEMS-based heating holder to conduct in-situ studies of solid-solid phase transformations and restructuring in 2D transition metal dichalcogenides (TMDCs). We use these structures to directly visualize phenomena such as the layer-by-layer phase transformation of MoTe₂ and the lattice reconstruction of 2D moirés. 

We also use custom-built 2D stacks to study the bending and bending-induced properties of 2D multilayers. We find that interlayer interactions play a major role in governing the bending of 2D stacks, where they lead to an unusually low bending stiffness in few-layer graphene and a curvature-dependence of the bending stiffness.[1] The key role of interfaces in the bending of 2D multilayers also indicates potential methods to tune the deformability of 2D systems though interfacial engineering [2]. Our techniques should enable the rational design of interfacial properties of devices based on 2D materials, including illustrating how to incorporate slippable interfaces and create deformable, stress-resilient electronics.

 

* Key contributors to this work: Edmund Han, Jaehyung Yu, Chia-Hao Lee, Yichao Zhang, Huije Ryu, Jangyup Son, M. Abir Hossain, Kenji Watanabe, Takashi Taniguchi, Gwan Hyoung Lee, Elif Ertekin, and Arend van der Zande