Characterization of Cd0.9Zn0.1Te based virtual Frisch grid detectors for high energy gamma ray detection

Detector grade CZT single crystals have been grown from zone refined Cd, Zn, and Te (similar to 7 N) precursor materials using a tellurium solvent method. Infrared transmission imaging has shown an average tellurium inclusion size of similar to 8 mu m in the as-grown crystal. Radiation detectors were fabricated in planar and virtual Frisch grid geometry and characterized for their spectroscopic performance. Charge transport properties revealed a high drift mobility of similar to 1200 cm(2)/V s and a mobility-lifetime product of similar to 2.8 x 10(-3) Cm-2/V. A detector with planar configuration (dimensions 6.9 x 6.9 x 4.8 mm(3)) showed an energy resolution of 4.7% for 59.5 keV gamma rays. The detector in a Frisch grid configuration (dimensions 4.2 x 6.2 x 6.5 mm(3)) exhibited an energy resolution of 1.4% for 662 keV gamma rays. Digital spectroscopic measurements were carried out using a high-resolution digitizer card. A biparametric correlation scheme was employed to study the effect of charge loss on energy resolution of the planar detector. Based on this correlation scheme, a digital correction method was applied and improved pulse-height spectrum was obtained for 662 keV gamma rays using the planar detector with spectral features comparable to those of the virtual Frisch grid detector. (C) 2012 Elsevier B.V. All rights reserved.