Microwave instability in n-type indium antimonide

Indium Antimonide emits microwave noise when it is subjected simultaneously to parallel dc electric and magnetic fields whose values exceed certain thresholds. Comparison of the emission characteristics at 77°K with those at 4.2°K shows two major differences. 1) The threshold magnetic field at 4.2°K is approximately half of that at 77°K. 2) With increasing magnetic field the emission at 4.2°K is comprised of a background continuum upon which are superimposed equally-spaced resonant spikes. At 77°K, the background continuum only is observed. A theoretical model for the threshold characteristics is presented based on the assumption that the observed instability arises from phonon excitation by the drifting electrons.