Nanoscale Structural Characterizations of 2D Materials Using Low-energy Electron Microscopy

Abstract

Low-energy electron microscopy (LEEM) is a powerful tool for investigating the structures of 2D materials at the nanoscale. In this paper, following a review of structural information obtained from LEEM characterizations, the growth of hexagonal boron nitride (hBN) and its heterostructures with graphene is investigated in detail using LEEM. We have demonstrated that unidirectional hBN islands grow on inclined Cu(101) surfaces, and that the orientation of these islands changes in response to the orientation of steps on the vicinal Cu(101) surface. This indicates that the Cu substrate steps play a key role in determining the orientation of hBN. Additionally, we have successfully controlled the growth of both lateral and vertical heterostructures of graphene and hBN on Cu substrates by adjusting the supply sequence of their precursors.