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Proceedings Paper

Temperature-dependent electronic decay profiles in CZT: probe of bulk and surface properties
Author(s): Royal Kessick; Hugh Maupin; Gary C. Tepper; Csaba Szeles
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Paper Abstract

The electronic performance of CZT-based gamma radiation spectrometers is governed by a synergism of bulk and surface properties. Compensation is used to increase the bulk resistivity of Cd1-xZnxTe (x~0.1), but the same electronic states that are introduced to increase the material resistivity can also trap charge and reduce the carrier lifetime. Electrical and mechanical surface defects introduced during or subsequent to crystal harvesting are also known to interfere with device performance. Using a contactless, pulsed laser microwave cavity perturbation technique, electronic decay profiles were studied in high pressure Bridgman CZT as a function of temperature. The electronic decay profile was found to depend very strongly on temperature and was modeled using a function consisting of two exponential terms with temperature-dependent amplitudes and time constants. The model was used to relate the observed temperature dependent decay kinetics in CZT to specific trap energies. It was found that, at low temperatures, the electronic decay process is dominated by a deep trap with an energy of approximately 0.69 ± 0.1 eV from the band edge. As the temperature is increased, the charge trapping becomes dominated by a second trap with an energy of approximately 0.60 ± 0.1 eV from the band edge. Surface damage introduces additional charge traps that significantly alter the decay kinetics particularly at low temperatures.

Paper Details

Date Published: 10 January 2003
PDF: 12 pages
Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); doi: 10.1117/12.455695
Show Author Affiliations
Royal Kessick, Virginia Commonwealth Univ. (United States)
Hugh Maupin, Virginia Commonwealth Univ. (United States)
Gary C. Tepper, Virginia Commonwealth Univ. (United States)
Csaba Szeles, eV Products (United States)


Published in SPIE Proceedings Vol. 4784:
X-Ray and Gamma-Ray Detectors and Applications IV
Ralph B. James; Larry A. Franks; Arnold Burger; Edwin M. Westbrook; Roger D. Durst; Edwin M. Westbrook; Roger D. Durst, Editor(s)

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