Gamma Ray Detection with Cd_0.9Zn_0.1Te Based Detectors Grown Using a Te Solvent Method

Abstract

Cd 0.9 Zn 0.1 Te (CZT) single crystal has been grown using a tellurium solvent method. Two CZT crystals have been chosen from two different locations of the grown ingot. The two crystals were characterized using infrared transmission (IR) imaging and radiation detectors in planar geometry were fabricated on them. Current-voltage characteristics (I-V) revealed a resistivity of ~8.6×10 10 cm for detector A (6.9×6.9×4.8 mm 3 ) and 6.7×10 10 cm for detector B (11.5×11.7×2.6 mm 3 ). IR imaging showed a lesser concentration of Te inclusions/precipitates in detector A. The transport properties viz., electron drift-mobility and electron mobility-lifetime product were measured using alpha spectroscopy in these detectors in a planar configuration. Detector A showed better charge transport properties compared to detector B. The superior transport properties of crystal A were reflected in the spectroscopic properties of the detectors. Gamma pulse height measurements using a 241 Am isotope revealed an energy resolution of ~5 % for detector A and ~7 % for detector B. A digital spectrometer and a biparametric correction scheme was incorporated to recover the pulse height spectrum of high energy gamma rays ( 137 Cs source) from the effect of poor hole movement. 576