Silicon field effect transistors for Terahertz detection and imaging

A channel of a Field Effect Transistor (FET) can act as a resonator for plasma waves. The plasma frequency of this resonator depends on its dimensions and for gate lengths of a micron and sub-micron (nanometer) size, can reach the Terahertz (THz) range. The interest in the applications of FETs for THz spectroscopy started at the beginning of 90s with the pioneering theoretical work of Dyakonov and Shur [1] who predicted that plasma oscillations in a FET channel can lead to the THz emission. This work was followed by another one where the same authors have shown that the nonlinear properties of the 2D plasma in the transistor channel can be used for detection of THz radiations [2]. It appeared very rapidly that THz detection by FETs can be very promising and close to practical applications. Recently, non-resonant plasma properties were successfully used for the room temperature broadband THz detection and imaging by silicon FETs.