Variable range hopping and nonlinear transport in monolayer epitaxial graphene grown on SiC

Abstract

We report experimental results on variable range hopping (VRH) and nonlinear transport in monolayer epitaxial graphene. In the linear regime in which the conductance is independent of voltage, the resistance curve derivative analysis method can be used to unequivocally determine whether Mott VRH or Efros–Shklovskii VRH is the dominant transport mechanism in our devices. In the nonlinear regime in which the conductance shows a strong dependence on voltage, we find that our experimental results can be successfully described by existing theoretical models. We suggest that the observed vastly different exponents in the threshold voltage–temperature dependence require further experimental and theoretical studies.