Characteristics of high-k Al2O3 dielectric using ozone-based atomic layer deposition for dual-gated graphene devices

We present characteristics of dual-gated graphene devices with an Al2O3 gate dielectric formed by an O3-based atomic-layer-deposition process. Raman spectra reveal that a O3 process at 25°C on single-layered graphene introduces the least amount defects, while a substantial number of defects appear at 200 °C. This graphene device with O3-based Al2O3 dielectric demonstrates a heterojunction within the graphene sheet when applying VTG and VBG and possesses good dielectric properties with minimal chemical doping, including a high dielectric constant ∼8, low hysteresis width ∼0.2 V, and low leakage current and a carrier mobility of 5000 cm2/V s 25°C in ambient.