Cadmium Telluride and Cadmium Zinc Telluride are still the most widely used substrate materials in CMT epitaxy. Much of the material which is available commercially has unsuitable electrical properties for on-substrate device fabrication. Other material contains impurities or defects which can lead to the growth of inferior quality epitaxial layers. Precipitates can be a major problem where they intersect the surface of the polished substrate. They may lead to surface defects in the epitaxial layer, or to the release of any impurities which may be present if dissolved by the growth solution in the case of growth from the liquid phase. Removal of these precipitates and control of the electrical properties of the substrate is therefore desirable so that optimum quality epitaxial material may be grown. Epitaxial growth of CMT from either the liquid phase or from the vapour phase involves heating the substrate in mercury vapour. This has an effect on the surface regions of the substrate which can be revealed using a suitable etch, and using a sectioning technique which enables the electrical properties through the thickness to be determined. A high temperature anneal in a Cadmium overpressure has been shown to modify the electrical properties and to reduce defect densities in commercial Cadmium Telluride material. (Ref. 1).

Date Published: 22 November 1986
PDF: 8 pages
Proc. SPIE 0659, Materials Technologies for Infrared Detectors, (22 November 1986); doi: 10.1117/12.938548

Published in SPIE Proceedings Vol. 0659:
Materials Technologies for Infrared Detectors
Jean Besson, Editor(s)