Investigation of the asymmetric characteristics and temperature effects of CdZnTe detectors

The results of our newest depth sensing coplanar grid CdZnTe detectors will be discussed. These detectors, which utilize the third-generation coplanar anode design, were fabricated by Baltic Scientific Instruments, Ltd., using crystals acquired from Yinnel Tech, Inc., having dimensions of 1.5 cm x 1.5 cm x 0.9 cm and 1.5 cm x 1.5 cm x 0.95 cm. Employing various compensation techniques, an energy resolution of about 1.7% full width at half maximum (FWHM) was achieved for 662-keV gamma rays. We observed that the spectral performance was highly dependent upon the biasing orientation of the detector. The [[mu].sub.e][[tau].sub.e] product for one of the crystals was measured and it was found to be a high value of 1.13 x [10.sup.-2] [cm.sup.2]/V. A study of the spectroscopic performance of CdZnTe for reduced temperature operation was implemented and we observed degraded performance for temperatures below 0[degrees]C and a complete loss of spectral information at -30[degrees] C. Index Terms--CdZnTe detector, coplanar grid, depth sensing, gamma-ray spectroscopy.