Evolution of the Raman spectra of electron beam irradiated graphene exposed in air

The modification of graphene’s properties is essential for its applications. During the device preparation and morphology characterization, graphene is usually irradiated by electron beam. The process may induce defects such as damage and doping in graphene. Moreover, when the irradiated graphene is exposed in air, the defects will adsorb impurities, such as gas atoms, atomic groups, or molecules, leading to changes of the properties of graphene. Therefore, it is important to study the evolution of the properties of the irradiated graphene exposed in air. In this paper, the time evolution of the Raman spectra of graphene after irradiated by electron beam was measured. It is found that D peak appears after irradiation, indicating the formation of defects. The Raman spectra at different time after irradiation show redshifts and blueshifts of the peaks, because the carriers was p-type at first and then became n-type finally. It signifies that air exposure has changed the conducting properties of the irradiated graphene. The results suggest that air exposure has significant effect on defect engineering of graphene.