In-situ Raman study of laser-induced graphene oxidation

We present in-situ Raman measurements of laser-induced oxidation in exfoliated single-layer graphene. By using high-power laser irradiation, we can selectively and in a controlled way initiate the oxidation process and investigate its evolution over time. Our results show that the laser-induced oxidation process is divided into two separate stages, namely tensile strain due to heating and subsequent $p$-type doping due to oxygen binding. We discuss the temporal evolution of the $D/G$-mode ratio during oxidation and explain the unexpected steady decrease of the defect-induced $D$ mode at long irradiation times. Our results provide a deeper understanding of the oxidation process in single-layer graphene and demonstrate the possibility of sub-$\mu$m patterning of graphene by an optical method.