Theory of negative-conductance amplification and of Gunn instabilities in "two-valley" semiconductors

A theory of negative-conductance amplification and of Gunn-effect oscillation in good agreement with experimental observations is developed for "two-valley" semiconductors such as GaAs and InP. The theory is based upon a conduction-band model in which the relative populations of two valleys of vastly different mobility are determined by the average electron temperature, the latter being described by energy transport equations. Numerical computer solutions of the dynamic equations identify different modes of sample behavior and give a clear indication of the microscopic physical processes relevant to each.