▎ 摘　　要

We have studied the carrier densities n of multilayer and monolayer epitaxial graphene devices over a wide range of temperatures T. It is found that, in the high temperature regime (typically T >= 200K), ln(n) shows a linear dependence of 1/T, showing activated behavior. Such results yield activation energies Delta E for charge trapping in epitaxial graphene ranging from 196 meV to 34 meV. We find that Delta E decreases with increasing mobility. Vacuum annealing experiments suggest that both adsorbates on EG and the SiC/graphene interface play a role in charge trapping in EG devices.