Measuring the Local Twist Angle and Layer Arrangement in Van der Waals Heterostructures

TL;DR

This paper introduces spectroscopic LEEM and micro-LEED techniques to locally measure twist angles and layer arrangements in Van der Waals heterostructures, demonstrated on MoS2/hBN, revealing interface properties and cleaving history.

Contribution

It presents novel spectroscopic LEEM and micro-LEED methods for local characterization of twist angles and layer stacking in Van der Waals heterostructures.

Findings

Effective assessment of hBN as a substrate.

Determination of cleaving history of MoS2 flakes.

Methods applicable to various 2D material heterostructures.

Abstract

The properties of Van der Waals heterostructures are determined by the twist angle and the interface between adjacent layers as well as their polytype and stacking. Here we describe the use of spectroscopic Low Energy Electron Microscopy (LEEM) and micro Low Energy Electron Diffraction ({\mu}LEED) methods to measure these properties locally. We present results on a MoS$_{2}$/hBN heterostructure, but the methods are applicable to other materials. Diffraction spot analysis is used to assess the benefits of using hBN as a substrate. In addition, by making use of the broken rotational symmetry of the lattice, we determine the cleaving history of the MoS$_{2}$ flake, i.e., which layer stems from where in the bulk.