Effects of surface Processing on the performance of Cd_1-xZn_xTe radiation detectors

The effects of polishing on the electron mobility-lifetime product of a detector-grade Cd_1-xZn_xTe (CZT) crystal is reported. The two surfaces of the crystal were deposited with Au layers and illuminated with subband light. A direct current (dc) photocurrent technique was used to measure the electron mobility-lifetime product as a function of the illuminating power. The measured dependence of the electron mobility-lifetime product on the photogenerated electron concentration was highly affected by the condition of the irradiated surface. This discovery has important implications for processing of CZT surfaces for radiation detector applications.