Thermally Evaporated SiO Serving as Gate Dielectric in Graphene Field-Effect Transistors

A thermally evaporated silicon monoxide (SiO) film has been experimented as the gate dielectric in graphene field-effect transistors (GFETs) due to its room-temperature and low-damage deposition without introducing chemical gases or ionized particles as in other film deposition techniques, which may cause damage to graphene. In order to evaluate the dielectric properties, a double-gated GFET was fabricated with a standard commercial thermally grown SiO 2 layer as the bottom gate dielectric and thermally evaporated SiO as the top dielectric. The electrical characterizations revealed that the top-gate carrier mobility was 1081.3 cm 2 /Vs, reasonably comparable to the bottom-gate mobility. Furthermore, the breakdown strength of the SiO film reached 5.7 MV/cm, which was lower than that of the SiO 2 dielectric (~10 MV/cm) but in the same order of magnitude. The breakdown mechanism of the SiO film was studied, and the current-voltage characteristics were in agreement with the Frenkel–Poole emission model. Finally, the relative dielectric constant of SiO was found to be 5.3, significantly higher than that of SiO 2 (3.9). These results indicate that the thermally evaporated SiO can function as an excellent dielectric for graphene-based devices.