Enhancement of graphene field-effect transistor by surface treatment

We report the enhancement of electrostatic transfer characteristics of fabricated graphene field-effect transistor (FET) by hexamethyldisilazane (HMDS) surface treatment. Charge carrier mobility increases by over 50% on average for both electron and hole. Impurity concentration also reduces by over 50% on average and charge neutrality point usually moves towards zero gate voltage. Electrostatic transfer characteristics of as fabricated FET show small variation with temperature resulting in weakly temperature sensitive carrier mobility. However, there is significant variation in characteristics between room temperature and 77 K after HMDS treatment and charge carrier mobility at 77K is almost two times the mobility at room temperature. We attribute the performance enhancements upon HMDS treatment to removal or modification of various contaminants present on graphene surface after device fabrication, which results in reduced carrier scattering. Dielectric screening of charged impurities may also contribute towards performance enhancements.