Tunable Terahertz Detection and Generation Using FETs Operating in the Saturation Regime

I report on the experimental observation of DC instability and self-amplification through stimulated emission of 0.2 and 1.63 THz radiation using InGaAs/GaAs HEMT operating in the deep saturation regime at room temperature. I demonstrate both theoretically and experimentally, that the Sub-THz and THz response of FETs are attributable to the rectification of the nonlinear dependence of the device's current-voltage characteristics. FETs function as nonlinear THz mixers and rectifiers, with their open-drain responsivity described by an expression analogous to that of a zero-bias Schottky diode detector. However, operating FETs in the deep saturation regime permits precise tuning of the device to the quantum localized resonance condition and the negative resistance mode at room temperature. Consequently, FETs can be adjusted in the deep saturation regime to facilitate tunable sub-THz and THz detection and generation as well as tunable sub-THz and THz lasing effect. These results are anticipated to significantly impact technological advancements across various fields in the near future.