In this work, the performance of InP-based HEMTs as a THz detector was experimentally studied. The nature of the THz rectification by the two-dimensional plasmons in which the DC drain current variation Delta I-d becomes maximal around the threshold voltage was observed. Based on the imaging measurement, it was confirmed that our HEMTs device can work for sensitive THz imaging at 0.3 THz. The directivity of the detector was characterized with the maximum responsivity of 26.1 V/W at theta = 160 degrees.
