Experimental evidence for Efros–Shklovskii variable range hopping in hydrogenated graphene

We have performed transport measurements on a hydrogenated graphene flake. It is found that conventional analysis cannot allow us to determine whether Mott variable range hopping (VRH) or Efros–Shklovskii (ES) VRH is the dominant mechanism in our system. By employing the modified resistance curve derivative analysis (RCDA) method, we are able to unequivocally show that ES VRH dominates and thus Coulomb interaction effects exist in our system at zero magnetic field. Transport data obtained in the intermediate and high field regimes also follow ES VRH based on the RCDA method. Our results suggest that Coulomb interaction effects can play an important role in disordered graphene.