Experimental Investigation of Inverted and Non-inverted Gate Architectures for Graphene TeraFETs

Antenna-coupled field-effect transistors (TeraFETs) have been shown to effectively detect THz radiation over the entire THz frequency range (0.1-10 THz). Beyond conventional semiconductor technologies, TeraFETs can be implemented with graphene as active material, leveraging both plasmonic and thermoelectric mechanisms for signal detection. Unlike conventional TeraFETs, graphene TeraFETs offer the novel design option to place the metal gate above or below the graphene sheet. In this contribution, we compare these two device architectures for TeraFETs with channels fabricated from exfoliated h-BN/graphene/h-BN stacks: One with a local gold top-gate and the other with a local gold back-gate, both integrated with identical bow-tie antennas for broadband operation. Our results indicate an improved detection performance when the local gate is placed underneath the h-BN-encapsulated graphene. While the graphene-TeraFETs with a local top-gate achieve a minimum optical NEP of 170 pW/√Hz, graphene-TeraFETs with a local back-gate exhibit an optical NEP value of 80 pW/√Hz, both determined at 350 GHz.