Zero-bias THz detection using graphene transistors

We report zero-bias millimeter-wave and sub-THz detection using graphene FETs up to 220 GHz and graphene heterostructure diodes with reduced 1/f noise in direct detection. This detection leveraged the nonlinearity of the channel resistance through resistive field-effect transistor mixing. At a 50 ohm load, measured device responsivity was 70 V/W at 2 GHz to 33 V/W at 110 GHz. The measured noise power of the graphene FETs was ~7.5 × 10^-18 V²/Hz at zero-bias. The NEP at 110 GHz was estimated to be ~80 pW/Hz^0.5. A linear dynamic range of >40 dB was measured, providing 15 - 20 dB greater linear dynamic range compared to conventional CMOS detectors at the transistor level.