Suppression of intrinsic roughness in encapsulated graphene

Abstract

Carrier mobility in graphene can be degraded by roughness. Here, the authors have measured the roughness of a suspended graphene layer encapsulated with hexagonal boron nitride (hBN) by diffraction in the transmission electron microscope. The 12-pm roughness measured is close to that found for carbon atoms within graphite. The simulations here show that encapsulation localizes flexural phonons in the hBN layers, leading to a suppression of roughness in the graphene. These results could lead to new strategies for device fabrication in applications requiring ultimately high performance, and show that layer roughness in artificially fabricated van der Waals heterostructures approaches that in naturally occurring bulk crystals.