Growth of Large-Area Cd.Zn.Te Single Crystals and Fabrication of Pixelated Guard-Ring Detector for Room-Temperature γ-Ray Detection

Abstract

Large-volume detector-grade Cd0.9Zn0.1Te (CZT) single crystals were grown using a vertical Bridgman technique. The bulk resistivity of the as-grown crystal was found to be \sim 5\times 10^{10}\,\,\Omega -cm from current-voltage measurements. A 19.0\times 19.0\times5.0 mm3 block of the crystal was used to fabricate a detector with 10\times 10 pixelated anode configuration integrated with interpixel guard rings. The detector was tested for its radiation detection properties using 662-keV gamma rays from a 137Cs source. The pixels exhibited well-resolved gamma pulse-height spectra (PHS) with percentage energy resolution 1.6% at 662 keV. A few pixels exhibited tailing of the photopeak on the lower energy side indicating the presence of hole traps. Biparametric plots (BPs) were obtained from digitally recorded preamplifier pulses. The BPs showed anomalous behavior, which was correlated with the gamma interactions in the active region of the detector in virtual Frisch grid configuration. The BPs also enabled to extract PHS free from the extensive tailing of the photopeak.