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

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2007-06, Vol.576 (1), p.90-94
• Main Authors: Veale, M.C., Sellin, P.J., Lohstroh, A., Davies, A.W., Parkin, J., Seller, P.
• Format: Article
• Language: English
• Subjects: CdZnTe; Mobility lifetime; Polarization; Trapping; Vertical Bridgman; X-ray
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2007.01.127

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.