Field effect in epitaxial graphene on a silicon carbide substrate

The authors report a strong field effect observed at room temperature in epitaxially synthesized, as opposed to exfoliated, graphene. The graphene formed on the silicon face of a 4 H silicon carbide substrate was photolithographically patterned into isolated active regions for the semimetal graphene-based transistors. Gold electrodes and a polymer dielectric were used in the top-gate transistors. The demonstration of a field effect mobility of 535 cm 2 ∕ V s was attributed to the transistor geometry that maximizes conductance modulation, although the mobility is lower than observed in exfoliated graphene possibly due to grain boundaries caused by the rough morphology of the substrate surface.