ABSTRACT
Commercially, cadmium zinc telluride (CdZnTe; CZT) and cadmium telluride (CdTe) are currently the most relevant II–VI compound semiconductor systems for x-ray and gamma-ray radiation detection. Various melt, solvent, and vapor phase crystal growth techniques have been employed over the years to produce CdTe and CZT single crystals. A closed-system approach to growing radiation detector-grade CZT is the traveling heater method (THM), in which the CZT crystallizes out of a solution. This is typically done in sealed quartz ampoules at temperatures well below the CZT melting point. Nonuniformities of the charge transport properties including defect-related steering effects within single crystals are typically enhanced by the incorporation of second-phase defects such as tellurium (Te) inclusions and extended dislocation networks around them. In principle, Te inclusions can be relatively easily removed by postgrowth annealing in cadmium (Cd)-rich vapor, which is practical to do on a wafer level. Finally, the chapter focuses on high-flux polarization phenomena in both photon counting and photocurrent modes.
