Symmetry Effects in Broadband, Room-Temperature Field Effect Transistor THz Detectors

Rectifying large area field-effect transistors (LA-FETs) are excellently suited for aligning high power pump-probe experiments. They offer the possibility of single-shot measurements, as well as the simultaneous measurement of optical near infrared pulses and their respective temporal delay. This paper studies the phase of the rectified signal of LA-FET detectors for low (similar to 100 GHz) and high (similar to 3.9 THz) THz frequencies. At low frequencies, the sign of the rectified current can be inverted by a source-gate bias while at high frequencies the sign remains constant.