UV ozone treatment for improving contact resistance on graphene

Abstract

Optimized UV ozone cleaning of graphene layers on SiO2/Si substrates is shown to improve contact resistance of e-beam evaporated Ti/Au contacts by three orders of magnitude (3 x 10(-6) Omega-cm(2)) compared to untreated surfaces (4 x 10(-3) Omega-cm(2)). Subsequent annealing at 300 degrees C lowers the minimum value achieved to 7 x 10(-7) Omega-cm(2). Ozone exposure beyond an optimum time (6 min in these experiments) led to a sharp increase in sheet resistance of the graphene, producing degraded contact resistance. The UV ozone treatment is a simple and effective method for producing high quality contacts to graphene. (C) 2012 American Vacuum Society. [http://dx.doi.org/10.1116/1.4754566]