Abstract
The frequency dependence of the drift velocity-field characteristics of n-type GaAs and the frequency limit of LSA-mode oscillations were investigated by solving the time dependent conservation equations of the electron number, momentum and energy for the lower and upper valleys. The velocity-field characteristics at high frequencies differed significantly from that for DC field and showed hysteresis loops. The maximum frequency of the LSA mode oscillation was estimated to be about 150 GHz.