Graphene and Lateral Heterostructure for THz Imaging

We report millimeter-wave and sub-terahertz detection using graphene FETs up to 220 GHz at zero-bias to reduce noise. Detection leveraged the nonlinearity of the channel resistance through resistive field-effect transistor mixing for high-dynamic range. At a 50- load, measured detection responsivity was 70 V/W at 2 GHz to 33 V/W at 110 GHz. The measured noise power of the graphene FETs was V /Hz at zero-bias. Noise equivalent power at 110 GHz was estimated to be pW/Hz . A linear dynamic range of dB was measured, providing 15–20 dB greater linear dynamic range compared to conventional CMOS detectors at the transistor level. The emerging graphene heterostructure diodes offer the RC limited cutoff frequency of 2.9 THz with the noise equivalent power of pW/Hz at 200 GHz due to its small junction- capacitance and diode nonlinearity.