Thin-film CdTe for imaging detector applications

Using the method of electrodeposition from aqueous electrolyte, we are able to grow thin films of CdTe as the basis of a direct semiconductor converter for large area X-ray imaging applications. This growth technique has the advantage of operating at low temperature with relatively low current densities and is therefore compatible, in principle, with a large-area hydrogenated amorphous silicon active matrix readout. Such a hybrid detector could prove to be an excellent optical sensor in the near term, and in the long-term advances in growth techniques may allow large area X-ray sensors to be fabricated. Currently, we are able to grow films to a thickness of 1 μm with reasonable mechanical quality. Problems that we have been identified in growing CdTe films include achieving good substrate adhesion and maintaining good stoichiometry over the full substrate area. Results will be presented to describe our approach to CdTe film growth and to show how film quality depends on both deposition time and electrolyte stirring rate.