Electronic properties of graphene/p-silicon Schottky junction

We fabricate graphene/p-Si heterojunctions and characterize their current–voltage properties in a wide temperature range. The devices exhibit Schottky diode behaviour with a modest rectification factor up to 102 . The Schottky parameters are estimated in the framework of the thermionic emission theory using Cheung’s and Norde’s methods. At room temperature, we obtain an ideality factor of about 2.5 and a Schottky barrier height of ∼0.18 eV, which reduces at lower temperatures. We shed light on the physical mechanisms responsible for the low barrier, discussing the p-doping of graphene caused by the transfer process, the exposure to air and the out-diffusion of boron from the Si substrate. We finally propose a band model that fully explains the experimental current–voltage features, included a plateau observed in reverse current at low temperatures.