Surface Reactions and Defect Formation in Irradiated Graphene Devices

Quantum mechanical-based kinetic Monte-Carlo calculations (KMC) are used to investigate mechanisms of degradation of graphene devices subjected to 10-keV x-ray irradiation, ozone exposure, and subsequent high-temperature annealing. Using KMC, we monitor the time evolution of defect concentrations on a graphene surface. The degradation mechanism for oxygen exposure and subsequent anneal of graphene surface greatly depends on the temperature and initial concentrations of H and O atoms on the graphene surface. At oxygen surface coverage of ~0.05 and higher, the damage is caused by formation of vacancies due to desorption of CO and CO2. Hydrogen facilitates the removal of O without introducing vacancies.