Tracing photodetection of THz frequency light in InAs nanowire field effect transistors via near-field THz nanoscopy

We trace the photodetection mechanisms at THz frequencies in InAs nanowire (NW) field-effect transistors (FET) by means of a combination of two near-field techniques: photocurrent nanoscopy and detectorless scattering near-field microscopy. By mapping local THz photocurrents with nanoscale (15 nm) spatial resolution we demonstrate the activation of photo-thermoelectric and bolometric effects under THz illumination of these room temperature nanodetectors.