Low-bias gate tunable terahertz plasmonic signatures in chemical vapour deposited graphene of varying grain size

Abstract

We report the characterization of centimeter sized graphene field-effect transistors with ionic gating which enables active frequency and amplitude modulation of terahertz (THz) radiation. Chemical vapour deposited graphene with different grain sizes were studied using THz time-domain spectroscopy. We demonstrate that the plasmonic resonances intrinsic to graphene can be tuned over a wide range of THz frequencies by engineering the grain size of the graphene. Further frequency tuning of the resonance, up to ∼65 GHz, is achieved by electrostatic doping via ionic gating. These results present the first demonstration of tuning the intrinsic plasmonic resonances in graphene.