Passivation of CdZnTe surfaces by oxidation in low energy atomic oxygen

A method of surface passivation of Cd1-xZnxTe (CZT) x-ray and gamma ray det ectors has been established by using microwave-assisted atomic oxygen bomba rdment. Detector performance is significantly enhanced due to the reduction of surface leakage current. CZT samples were exposed to an atomic oxygen e nvironment at the University of Alabama in Huntsville's Thermal Atomic Oxyg en Facility. This system generates neutral atomic oxygen species with kinet ic energies of 0.1-0.2 eV. The surface chemical composition and its morphol ogy modification due to atomic oxygen exposure were studied by x-ray photoe lectron spectroscopy and atomic force microscopy and the results were corre lated with current-voltage measurements and with room temperature spectral responses to Ba-133 and Am-241 radiation. A reduction of leakage current by about a factor of 2 is reported, together with significant improvement in the gamma-ray line resolution. (C) 1999 American Vacuum Society. [S0734-210 1(99)00201-8].