Nanoscale morphology of graphene on different substrates

Graphene layers can be used as the conductive channel in metal oxide semiconductor field effect transistors, metallic electrodes in capacitors, etc. However, when graphene is grown by chemical vapor deposition (CVD), substrate-induced corrugations and strain-related wrinkles formed on the graphene layer impoverish the properties of these devices by lowering the conductance and increasing their variability. In this work, different nanoscale experimental techniques have been used to investigate the morphology of as-grown and transferred graphene sheets on different substrates. We show that while the compressive strain (from the growth process) in the graphene sheet on flat substrates is minimized by generating wrinkles, on rough substrates it can be minimized by improving the graphene-substrate adhesion, leading to lower densities of wrinkles. This method allows the design of wrinkle-free graphene based devices.