Top-gated graphene field-effect-transistors formed by decomposition of SiC

Top-gated, few-layer graphene field-effect transistors (FETs) fabricated on thermally decomposed semi-insulating $4H-SiC$ substrates are demonstrated. Physical vapor deposited $SiO2$ is used as the gate dielectric. A two-dimensional hexagonal arrangement of carbon atoms with the correct lattice vectors, observed by high-resolution scanning tunneling microscopy, confirms the formation of multiple graphene layers on top of the SiC substrates. The observation of $n$-type and $p$-type transition further verifies Dirac Fermions’ unique transport properties in graphene layers. The measured electron and hole mobilities on these fabricated graphene FETs are as high as 5400 and $4400cm2∕Vs$⁠, respectively, which are much larger than the corresponding values from conventional SiC or silicon.