CdTe and CdZnTe Crystal Growth and Production of Gamma Radiation Detectors

Abstract

Bridgman CdTe and CdZnTe crystal growth, with cadmium vapor pressure control, is applied to production of semiconductor gamma radiation detectors. Crystals are highly donor doped and highly electrically conducting. Annealing in tellurium vapors transforms them into a highly compensated state of high electrical resistance and high sensitivity to gamma radiation. N-type detectors, equipped with ohmic contacts, and a grounded guard ring around the positive contact, are not sensitive to hole trapping. Conductivity control, by the doping level, optimizes the detector operation by trade-off between electrons' lifetime and electrical resistance. Gamma spectra of single detectors and detector arrays are presented. Detector optimization and gamma detection mechanisms are discussed.