Soft Plasma Mode in GaAs

Abstract

Pytte and Thomas have predicted that in samples showing the Gunn effect the plasma frequency ${\ensuremath{\omega}}_{p}$ will go to zero as the electric field approaches the Gunn threshold. Here we calculate ${\ensuremath{\omega}}_{p}$ for GaAs, using a two-valley model, and find that (1) the actual variation with field is somewhat different from that predicted and (2) ${\ensuremath{\omega}}_{p}$ will not vanish in samples with carrier concentration greater than about ${10}^{18}$ / ${\mathrm{cm}}^{3}$.