Electronic properties of anodic bonded graphene

Here, we report electronic properties of graphene field-effect transistor in a magnetic field of 9.0 tesla. Raman spectroscopy on graphene sample prepared by anodic bonding method shows it to be of the highest quality. The observation of charge neutrality point at a positive gate voltage is due to hole doping in the sample from the immobile oxygen ions created during anodic bonding process. Hysteresis observed in the longitudinal resistance (between source and drain) while sweeping voltage at gate in a loop may be due to high viscosity of polythene oxide matrix for mobile Li ions. The longitudinal resistance as a function of gate voltage Vg shows that both kind of charge carriers (electron and hole) can be doped in graphene, which is further ascertained by the Hall measurements.