Direct formation of solution-based Al₂O₃ on epitaxial graphene surface for sensor applications

We propose a method for fabricating high-performance epitaxial graphene field-effect transistors (EG-FETs), involving a microwave-annealing-treated solution-based Al₂O₃ (MWA-treated sol-Al₂O₃) layer as a gate dielectric. The MWA process substantially preserves the pristine properties of EG with minimal hole doping and strain induction. The MWA-treated sol-Al₂O₃ showed a surface roughness of ~0.33 nm, a dielectric constant of 7.5, and a leakage current of 8.7 × 10⁻⁶ A/cm². The transconductance of the MWA-based EG-FET presents an enhanced field effect mobility by a factor of about 8 compared with the EG-FET with a natural oxide of Al.