Rapid synthesis of CVD graphene with controllable charge carrier mobility

Abstract

A high mobility of charge carriers and a low sheet resistance in graphene are the key indicators of its quality and applicability in electronic devices. In turn, the mobility of charge carriers in graphene is determined by graphene film smoothness. The electron scattering on structure defects of graphene film (wrinkles and grain boundaries) strongly affects the charge carrier mobility. In this work a simple and ultrafast approach for synthesis of graphene monolayer with the controllable smoothness and wrinkle density onto a resistively heated copper foil is presented. The method is a cold-wall chemical vapor deposition from methane. The fast synthesis of graphene with a full process cycle of 3 min is demonstrated. The structural defect density of polycrystalline graphene is optimized by appropriate combinations of methane concentration in the chamber and duration of synthesis process. Under the lower concentration of methane with the longer synthesis time the lower defect density in graphene appeared. The increase of process time from 30 s up to 10 min (under the decrease of methane concentration from 4.5 % to 0.36 %, respectively) leads to increase of average distance between wrinkles in graphene film from 6 µm to 35 µm. А charge carrier mobility as high as 2170 cm²V⁻¹s⁻¹ and a sheet resistance as low as 318 Ohm/□ under the lowest wrinkle density are measured for graphene polycrystalline monolayer deposited onto SiO₂ substrate.