Synthesis of few-to-monolayer graphene on rutile titanium dioxide

We demonstrate a chemical-vapor-deposition (CVD)-based approach for the direct synthesis of graphene on insulator with high-dielectric-constant (high-κ). Rutile titanium dioxide (TiO₂), an insulator with reported k value of 80–125, is selected as the growth-initiating layer for graphene. A two-step CVD process is shown to grow graphene directly on TiO₂ crystals or exfoliated ultrathin TiO₂ nanosheets without using any metal catalyst. Various material characterization techniques confirm the growth of few-to-monolayer of graphene. Annealing of the growth substrate at 1100 °C under atmospheric pressure, prior to the low-pressure CVD process, is needed for activating nucleation sites in subsequent graphene synthesis. Electrical behavior of a field-effect transistor fabricated on the graphene/TiO₂ heterostructure shows p-type doping in the CVD-synthesized graphene.