Realization of graphene field-effect transistor with high-κ HCa ₂Nb₃O₁₀ nanoflake as top-gate dielectric

A high-quality HCa₂Nb₃O₁₀ (HCNO) nanoflake (ε_r = 9.1) consisting of high-κ perovskite nanosheets is adopted as a gate dielectric for graphene-based electronics. A dual-gated device was physically constructed by directly dry-transferring a 22-nm-thick HCNO nanoflake as a top gate dielectric onto graphene. The fabricated graphene field-effect transistor could be operated at biases <1.5 V with a gate leakage below 1 pA. The top-gate capacitance and mobility of the dual-gated graphene device at room temperature were estimated to be 367 nF/cm² and 2500 cm²/V·s, respectively. These results show that HCNO can be employed as an alternative dielectric for graphene-based devices.