Improvement of carrier mobility of top-gated SiC epitaxial graphene transistors using a PVA dielectric buffer layer

The effects of treatment with polyvinyl alcohol (PVA) and a dielectric film of HfO2 on the properties of SiC based epitaxial graphene have been explored and analyzed. We have characterized the carrier mobility of graphene on Si-face and C-face SiC with a layer of HfO2, with or without an initial PVA treatment on the device active layer. Epitaxial graphene grown on the C-face displays a higher mobility than a film grown on the silicon face. Also, the mobility in the presence of the PVA treatment with HfO2 dielectric layer has been improved, compared with the mobility after deposition of only gate dielectric: similar to 20% in C-face graphene and similar to 90% in Si-face graphene. This is a major improvement over the degradation normally observed with dielectric/graphene systems.