Control of device characteristics by passivation of graphene field effect transistors with polymers

We investigate the possibility of controlling electrical characteristics of graphene-based field effect transistors (GRFETs) by passivating top or bottom surface of graphene with polymers. As-fabricated GRFETs made of graphene synthesized with chemical vapor deposition and transferred to a Si/SiO2 substrate typically exhibit p-type doping and hysteresis originated from polymer residue and O-2/H2O in the ambient atmosphere. We applied poly(vinyl alcohol, PVA) and polydimethylsiloxane (PDMS) and their stacks as passivation layers on graphene at the bottom or top surface to control device characteristics. Depending on the polymer, n-type doping (compensation of p-type doping), suppression of hysteresis, and enhancement of mobility are observed. Air stability of the passivation methods is also investigated. (C) 2016 Elsevier B.V. All rights reserved.