Terahertz Gunn-like oscilations in InGaAs/InAIAs planar diodes

Abstract

A microscopic analysis of self-generated Terahertz (THz) current oscillations takingplace in planar InAlAs/InGaAs slot-diodes operating under dc bias is presented. Anensemble Monte Carlo (MC) simulation is used for the calculations. The onset of theoscillations is threshold-like, for drain-source voltages surpassing 0.6 V. Gunn-like mechanisms and the modulation of the injection of electrons into the recess-to-drain region, which takes place in the ? or L valleys alternatively, are found at the origin ofthe phenomenon. THz frequencies are reached because of the presence of ultra-fast electrons in the region of interest. Extremely high velocities are achieved by (i) the effect of the recess, which focuses the electric field and launches very fast electrons into the drain region, and (ii) the influence of degeneracy, which significantly reduces the rate of scattering mechanisms and enhances the electron mobility in the channel.