Charge-fluid heating in quasi-ballistic plasmonic FETs

Abstract

We have studied the thermal effects in quasi-ballistic plasmonic field effect transistors (FETs), for which the total energy of the plasma fluids does not dissipate, because the inelastic scattering is negligible. Instead, losses of the fluid momentum lead to redistribution of energy, lost during the deceleration of the flux between “chaotic” degrees of freedom, i.e., a specific heating of the fluid. For the steady-state regimes and nondegenerate electrons, we have found the exact solutions for the distribution of fluid velocity, plasma concentration, and temperature along the FET channel. The fluid heating demonstrates an unusual feature—the heating is small for large currents (for the large ballisticity of the electrons) and is larger for small currents (lesser ballisticity). Spatial distributions of the electron temperature are monotonous at moderate currents, but they become non-monotonous, approaching critical currents. The found thermal effects point out the highly nonlocal characteristic of the heat generation and transport in quasi-ballistic plasmonic FETs. The heating effects are illustrated for the GaAs- and GaN-based devices.