Leakage and field emission in side-gate graphene field effect transistors

摘要

We fabricate planar graphene field-effect transistors with self-aligned side-gate at 100nm from the 500 nm wide graphene conductive channel, using a single lithographic step. We demonstrate side-gating below 1V with conductance modulation of 35% and transconductance up to 0.5 mS/mm at 10mV drain bias. We measure the planar leakage along the SiO_2/vacuum gate dielectric over a wide voltage range, reporting rapidly growing current above 15 V. We unveil the microscopic mechanisms driving the leakage, as Frenkel-Poole transport through SiO_2 up to the activation of Fowler-Nordheim tunneling in vacuum, which becomes dominant at higher voltages. We report a field-emission current density as high as 1 μA/μm between graphene flakes. These findings are important for the miniaturization of atomically thin devices.