X-ray spectroscopy and charge transport properties of CdZnTe grown by the vertical Bridgman method

Abstract

We have studied the spectroscopic performance and charge transport properties of planar detectors fabricated from single crystal Cd 1− x Zn x Te ( x = 0.1 ) grown using the modified vertical Bridgman technique. For the measurement of medium energy X-rays (10–50 keV), an energy resolution of 3 keV (FWHM) was observed; however performance was seen to degrade at temperatures below 260 K. The charge transport properties of electrons were studied as a function of temperature using 241Am 5.5 MeV α-particles. At room temperature, the measured electron mobility-lifetime product ( μτ) was 1.25±0.02×10 −3 cm 2 V −1, which decreased with cooling. Evidence was found for the creation of an internal polarization field at lower temperatures consistent with the presence of deep levels with a relatively high concentration and/or capture cross-section. An analysis of the temperature dependent electron drift mobility also indicates the presence of shallow electron traps at E A∼0.2 eV.