Progress in Cadmium Sulfide

Considerable progress has been made during the last two years in both the understanding and application of cadmium sulfide, which is an outstanding photoconductor material. Improved crystal growing techniques have resulted in large single crystals with more perfect crystal structure and higher purity. Further improvements in purity are sought by zone refining of cadmium and sulfur. Ultrasonic cutting methods have been applied successfully to shaping the crystals. High-temperature, high-pressure equipment has been used to grow crystals from the melt. P-type CdS crystals have been produced by heavy copper doping. Thin film techniques have been advanced. Surface volume studies of photoconductors have been made, which clarify certain surface deteriorations. Methods of producing ohmic and barrier electrodes have been improved. All of these fundamental studies have contributed to an improvement in the efficiency, stability, and uniformity of elements used in devices such as photocells, gamma detectors, solar generators, and photorectifiers.