Monte Carlo investigation of terahertz plasma oscillations in gated ultrathin channel of n-InGaAs

Abstract

By numerical simulations we investigate the dispersion of the plasma frequency in a gated channel of n-type InGaAs layer of thickness W and submicron length L at T=300 K. In the presence of a source-drain voltage and for a carrier concentrations of 1018 cm−3 the spectra evidences a peaked shape with two main bumps, the former at high frequency corresponding to the three-dimensional plasma frequency and the latter at a low frequency. The frequency value of the latter peak exhibits a dispersion as the inverse of the channel length in agreement with the predictions of gradual channel approximation. At increasing drain voltages the instabilities associated with the presence of Gunn domains are responsible for a suppression of the plasma peak in favor of the onset of a peak in the subterahertz domain associated with transit time effects.