Some Properties of Cu Doped CdS Single Crystals Grown from the Melt

Abstract

CdS single crystals for ultrasonic amplifiers were grown from the Bridgman method under high pressure. The conductivities of these crystals were too high to get the ultrasonic amplification in the as-grown states. Cu impurity was therefore doped in the crystals to compensate the conduction electrons. By this treatment the conductivities decreased to 10^-7mho/cm or less at room temperature and the crystals were very photosensitive. By using these crystals the ultrasonic amplification of shear mode was measured at 60MHz and its acoustic gain was about 80dB/cm. The drift mobilities obtained from ultrasonic amplification measurements depended upon the photoconductivities; the mobility at the conductivities lower than 10^-4mho/cm was small as compared with the mobility of higher conductivities. The drift mobility over 10^-4mho/cm was 240-260cm²/v·sec which was nearly equal to Hall mobility, Measured Hall mobilities did not depend upon the photoconductivities.