Characterization of Single Crystal Mercuric Iodide (HgI₂) Using Thick Detector Structures

Abstract

Single crystal sections of HgI2 (about 1 cm thick) have been evaluated for charge carrier transport properties. Using these thick detector structures, surface effects produced during fabrication are reduced, enhancing the bulk property characteristics. The standard time-of-flight method was used to determine electron and hole mobilities. Lifetime measurements for electrons and holes were made by direct observation of the carrier decay where crystal transit times were long compared to lifetimes. Nonlinear charge carrier velocities have been observed during mobility measurements. These nonlinearities impair a partial charge collection technique [1,2,3] for spectra generation taken with thick detectors while having a lesser effect on the standard full charge collection approach. Partial charge collection methods have produced greater peak efficiencies than full charge collection, and investigations of crystal properties are being used to enhance this method.

Pulse shape analysis for electron mobility study in cadmium zinc telluride gamma-ray detectors

“…The electron mobility was then extracted from the slope of the linear fit using the simple relation (2) where is the rise time, is the CZT thickness (1 cm), is the applied voltage, and is the electron mobility. A similar approach was used by Beyerle et al [7], Burshtein et al [8] and Eisen et al [9]. However, Burshtein et al used short light pulses (10 ns) as their source from a frequency-doubled Nd:YAG laser in their experiments.…”