Some Plasma Effects in Semiconductors

This is a review of some selected plasma effects in semiconductors, principally InSb at 77° K. The production of nonequilibrium electronhole plasmas by electrical injection and impact ionization is described including some instabilities which attend the latter process. Some new results on the pinch effect obtained by diagnosis with a 10.6 ¿ CW laser are shown. Observations of the manifestation of another instability, namely gigahertz radiation, not requiring an applied magnetic field are presented. A magnetic field is required to produce some instabilities in plasmas, among these are the helical instability. A bistable element resulting from an inherent hysteresis in the threshold conditions of this instability is described. Discontinuous changes in the plasma conductance can be produced by a magnetic field and the relation of this effect to high intensity microwave emission is outlined. Finally, some preliminary results on plasma decay are presented.