The potential for sensitivity enhancement by the thermoelectric effect in carbon-nanotube and graphene Tera-FETs

Abstract

We report on terahertz (THz) measurements with graphene field-effect transistors with integrated antennas (Tera-FETs) and lay special emphasis on thermoelectric contributions to the detected THz photoresponse. Graphene Tera-FETs with integrated broad-band bow- tie antennas were fabricated in a CVD-based growth process and were successfully applied for detection at 600 GHz with optical NEPs down to 515 pW/√Hz. While rectification of THz radiation by (distributed) resistive mixing of charge-density waves induced in the gated transistor channel region is well known, significant additional contributions to the detected signal have experimentally been observed and hot-carrier thermoelectric effects have been identified as a possible origin of these signals. We also observe similar signal contributions in carbon- nanotube transistors.