Ultrasonic Attenuation in the Magnetic Freeze-Out and Carrier Hopping Regions of n-InSb

Abstract

Ultrasonic attenuation was measured on n-InSb with an excess donor concentration of 6.1×1013 cm-3 at low temperatures down to 0.3 K in magnetic fields up to 40 kG. In the magnetic freeze-out region, the attenuation exhibited a peak which shifted toward lower fields with decreasing temperature. On the other hand, the attenuation in the hopping region was quenched and the change with respect to magnetic field or temperature was much reduced. These results indicate that the attenuation is caused only by free electrons which can move so as to screen the electric fields associated with ultrasonic waves.