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Defects and impurities in mercuric iodine processing

Description: In the fabrication of mercuric iodide HgI{sub 2} room temperature radiation detectors, as in any semiconductor process, the quality of the final device is very sensitive to the impurities and defects present. Each process step can change the effects of existing defects, reduce the number of defects, or introduce new defects. In HgI{sub 2} detectors these defects act as trapping and recombination centers, thereby degrading immediate performance and leading to unstable devices. In this work we characterized some of the defects believed to strongly affect detector operation. Specifically, we studied impurities that are known to be present in typical HgI{sub 2} materials. Leakage current measurements were used to study the introduction and characteristics of these impurities, as such experiments reveal the mobile nature of these defects. In particular, we found that copper, which acts as a hole trap, introduces a positively charged center that diffuses and drifts readily in typical device environments. These measurements suggest that Cu, and related impurities like silver, may be one of the leading causes of HgI{sub 2} detector failures.
Date: March 1, 1996
Creator: van Scyoc, J.M.; James, R.B.; Schlesinger, T.E. & Gilbert, T.S.
Partner: UNT Libraries Government Documents Department

Spatial Mapping of Cadmium Zinc Telluride Materials Properties and Electrical Response to Improve Device yield and Performance

Description: Cadmium zinc telluride has experienced tremendous growth in its application to various radiation sensing problems over the last five years. However, there are still issues with yield, particularly of the large volume devices needed for imaging and sensitivity-critical applications. Inhomogeneities of various types and on various length scales currently prevent the fabrication of large devices of high spectral performance. This paper discusses the development of a set of characterization tools for quantifying these inhomogeneities, in order to develop improvement strategies to achieve the desired cadmium zinc telluride crystals for detector fabrication.
Date: January 26, 1998
Creator: Scyoc, J. M. Van; Brunet, B. A.; Yoon, H.; Gilbert, T. S.; Hilton, N. R.; Lund, J. C. et al.
Partner: UNT Libraries Government Documents Department