Charge Trapping in Monolayer and Multilayer Epitaxial Graphene

Abstract

We have studied the carrier densitiesnof multilayer and monolayer epitaxial graphene devices over a wide range of temperaturesT. It is found that, in the high temperature regime (typicallyT≥ 200 K),ln⁡(n)shows a linear dependence of 1/T, showing activated behavior. Such results yield activation energiesΔEfor charge trapping in epitaxial graphene ranging from 196 meV to 34 meV. We find thatΔEdecreases 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.