Phase-sensitive Silicon CMOS TeraFETs

Short channel Si CMOS could detect both the intensity and phase of the impinging THz or sub-THz radiation enabling line-of-sight detection and spectroscopic operation. The phase control is also crucial for phase-synchronized TeraFET arrays. We introduce and calculate the characteristic phase control frequency for silicon NMOS as a function of the channel length. The response depends on the effect of momentum, relaxation time, and the viscosity of the electronic fluid. Parasitic elements such as source and drain series resistances, fringing gate capacitances, and scattering at the contacts also play an important role. Our analysis for 20nm, 65nm, and 130 nm technology nodes shows that Si NMOS could detect the phase of impinging THz radiation in the broad frequency range (from $\sim100$ GHz (for 130 nm technology) to approximately 10 THz (for 20 nm technology) via the interference of the plasmonic oscillations propagating from the source and drain sides of the channel. This conclusion is confirmed by the simulation of the spectrometer response for 20 nm and 130 nm Si NMOS. These results could guide the development of future generations of Si sub-THz and THz phasesensitive photodetectors.