Terahertz Small-Signal Response of Field-Effect Transistor Channels

In this paper, we present an analytical approach for the study of the small-signal response of nanometric field-effect transistor at terahertz frequencies. One-dimensional hydrodynamic equations coupled with a pseudo-two-dimensional Poisson equation are derived at first-order to obtain the small-signal admittance matrix describing the transistor. This matrix is then used to model the loaded device and establish its voltage amplification. The admittances and voltage amplification spectra exhibit sharp resonances associated with the plasma modes of the channel. The influences of the device geometry, operating temperature and connected load are investigated.