The surface and interface evolution of graphene under air exposure

Graphene, as a channel material in radio-frequency (RF) electronic devices, has shown great application prospect because of its excellent electrical properties. At present, remarkable progress has been made in graphene RF transistors. However, there are still many factors that affect the yield of device, and the state of graphene is an important factor in device failure. In this paper, the changes occurred in single-crystal graphene grown by chemical vapor deposition (CVD) exposed to air were studied as time prolonging. After oxidization in air, surface morphology showed significant change. Redshift of G and 2D peaks of graphene grown on Cu foil were found in Raman spectra, which means that the graphene is in a state of tensile strain. Substrates oxidized at ambient conditions produced more irregular steps and higher roughness. The interface state of graphene and underneath Cu substrate was studied and the relationship between graphene oxidation and substrate crystallographic plane was clarified by electron backscattered diffraction (EBSD). It is instructive to perform a specific Cu surface to grow high quality graphene for RF electronic devices with less device failure.