Temperature-dependent electronic decay profiles in CZT: probe of bulk and surface properties

Royal Kessick; Hugh Maupin; Gary C. Tepper; Csaba Szeles

doi:10.1117/12.455695

10 January 2003 Temperature-dependent electronic decay profiles in CZT: probe of bulk and surface properties

Royal Kessick, Hugh Maupin, Gary C. Tepper, Csaba Szeles

Proceedings Volume 4784, X-Ray and Gamma-Ray Detectors and Applications IV; (2003) https://doi.org/10.1117/12.455695
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

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 Cd_1-xZn_xTe (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.

Citation Download Citation

Royal Kessick, Hugh Maupin, Gary C. Tepper, and Csaba Szeles "Temperature-dependent electronic decay profiles in CZT: probe of bulk and surface properties", Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); https://doi.org/10.1117/12.455695

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