Chemical etching and surface oxidation studies of cadmium zinc telluride radiation detectors

Abstract

AbstractCdZnTe (CZT) is commonly used as a radiation detector material and the surface properties are important as they influence detector performance. The surface chemistry is generally controlled through chemical etching and oxidation processes. In this paper, X‐ray photoelectron spectroscopy (XPS) is employed to investigate changes in the surface composition of single‐crystal Cd0.95Zn0.05Te samples after exposure to bromine in methanol (BM) chemical etching treatments and subsequent oxidation in air or 30% H2O2. BM treatment of CZT is found to result in a graded Te‐rich surface layer which increases in thickness as a function of BM concentration. Room‐temperature air oxidation of 0.2% BM‐treated CZT follows a logarithmic rate law. BM‐treated CZT exposed to 30% H2O2 for 30 s shows a linear increase in the TeO2 oxide thickness with increasing BM concentration up to a BM concentration of 1.5%. Above 2% BM concentration, the Te enrichment in the CZT surface region has reached saturation and is effectively pure Te. Copyright © 2010 John Wiley & Sons, Ltd.