Microwave measurement of the velocity-field characteristic of GaAs

This paper summarizes investigations of the velocity-field characteristic of both bulk and epitaxial GaAs as determined from measurements of the average conductivity of bar samples in a large microwave field. The characteristic for both epitaxial and bulk material with resistivity about 1 Ω.cm is similar to that reported by Ruch and Kino, and to that calculated from solutions of the Boltzmann equation. The bulk material, however, shows a decrease of negative differential mobility with increasing resistivity. The non-linear partial differential equation in one dimension and time governing the field in the samples has been solved numerically and the evolution of the field rearrangement under these experimental conditions has been modelled to show the validity of this technique.