 |
Charge density rearrangement when graphene is in contact with a silica substrate. On the left, when graphene is close to the silica substrate. On the left, when it is at a larger distance. The top panel shows a top view and the lower panels show a side view. |
Electronic states localized at the surface of oxide semiconductors are a common cause of their low ionization potential. We study the properties of these surface states using density functional theory (DFT) and show that they strongly affect the intrinsic doping of graphene on oxidized silicon substrates. We present simple empirical model that it is parameterized from the DFT calculations. The model demonstrates that Dirac voltages as large as 50 V and intrinsic n-doping are produced by the presence of these surface states. We extend it to include the effect of other adsorbates that modify the dielectric properties of the device.
This research area provides opportunities for undergraduate research.