First principle study of the thermal conductance in graphene nanoribbon with vacancy and substitutional silicon defects

Abstract

The thermal conductance in graphene nanoribbon with a vacancy or silicon point defect is investigated by nonequilibrium Green's function (NEGF) formalism combined with first-principles calculations of density-functional theory with local density approximation. The thermal conductance is very sensitive to the position of the vacancy defect, while insensitive to the position of silicon defect. A vacancy defect situated at the center of the nanoribbon generates a saddlelike surface, which greatly reduces the thermal conductance by strong scattering to all phonon modes; while an edge vacancy defect only results in a further reconstruction of the edge and slightly reduces the thermal conductance. © 2011 American Institute of Physics.