2, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Atomically precise manipulation of graphene and other 2D materials holds promise for fields as diverse as quantum electronics and nanopore sensing. However, manipulation of these materials often assumes a ‘pristine’ system free of contaminants and other detrimental constituents. Recently, several studies have begun to describe and characterize the prevalence and implications of adsorbed hydrocarbon-based contaminants on graphene and other emerging 2D materials. These studies indicate that contamination often occludes the majority of exposed surfaces of the materials of interest and that it has high surface mobility and low volatility – a combination that causes it to be challenging to remove or control in scanning probe and beam-based modification. Although present on virtually all graphene devices with an exposed surface, only recently have the implications of the contamination begun to be acknowledged in the literature. With a growing body of research characterizing the contamination with Raman, XPS, AFM, SIMS, and especially STEM, an understanding of the challenge is emerging. Here we provide an overview of sources of contamination, characterization of the properties and composition, an assessment of the implications for utilizing these materials, along with strategies for mitigation.