(485g) Modelling the Effect of Electron Beam Irradiation on the Thermal Conductivity of Monolayer Graphene

In this work, we computationally investigate the effect of electron beam irradiation on thermal conductivity and morphology of a sample of graphene. We model the irradiation process using kinetic Monte Carlo (KMC) technique to predict the generation and evolution of vacancy defects as well as the reaction of defective sites with the residual impurities. The energy barriers for each of the possible processes considered are calculated from density functional theory (DFT) and the associated rates are obtained from transition state theory. At each electron beam energy, we estimate the average thermal conductivity of the equilibrium configuration using reverse non-equilibrium molecular dynamics (RNEMD) simulations. We show that with increasing electron beam energies, the defect density increases resulting in poor thermal transport across the graphene nanostructure. In addition, we evaluate the phonon density of states (VDOS) of pristine graphene and graphene irradiated at different electron beam energies from MD simulations. The reduction in the thermal conductivity is explained by the corresponding changes in the VDOS curves. Our results help in understanding the reason for the wide scatter in the reported experimental thermal conductivity values, which strongly depends on the synthesis conditions and the characterization techniques used.