Mean free paths of charge carriers in CZT crystal

Abstract

The asymmetrical distortion of the Cadmium Zinc Telluride ((CZT) energy spectrum is mainly caused by the hole trapping in the CZT crystal, and it can be characterized by the mean free path of hole. The mean free paths of the charge carriers in the CZT crystal can be extracted from fitting the peak shape of the measured energy spectrum. The energy spectra of gamma-rays from Am-241, and that of alpha particles from (238)pU were measured with a CZT with 5 x 5 x 5 mm(3). The mean free path of the electron was determined from the bias dependence of alpha-particle response. The energy spectra of gamma-ray were simulated with EGSnrc code, in which Hecht equation was included, and the mean free path of the hole was determined by comparing the measured spectrum with the simulated one. The energy spectrum of 662 keV gamma-ray was measured with the CZT detector, and it was compared with the simulated spectrum, in which newly determined mean free paths of the electron and the hole were used.