Direct Observation of Self-Pinched Plasma Distribution in Indium Antimonide

Abstract

Plasma density distributions near the crystal surface in intrinsic InSb (at 220°K) have been “directly” observed by using a microwave probe technique. Short current pulses were used to avoid heating. For currents higher than the critical current for self-pinching, the plasma density was concentrated at the center of the crystal leaving the thermal equilibrium density throughout the rest of the crystal. From the time dependence of the microwave impedance, the pinch time and lifetime of the excess carriers were estimated. The plasma density distribution was flattened in the presence of longitudinal magnetic fields. When transverse magnetic fields were applied, even for currents below breakdown, non-uniform plasma densities were observed due to the Suhl effect. In addition, several kinds of oscillations in the plasma density were observed.