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The spectral performance as a function of the dielectric layer thickness for several CdZnTe Frisch collar devices was investigated. Seven different planar bar shaped detectors were fabricated from Redlen Technologies CdZnTe, and many Frisch collar devices were prepared from each planar device. The optimum dielectric layer thickness was experimentally determined for each device. The result of the optimal thickness study was verified through three-dimensional geometry modeling of the potential and electric field. It is shown that there exists an optimal dielectric layer thickness for best performance for CdZnTe Frisch collar devices with aspect ratios (L/W) greater than 2.5. [ABSTRACT FROM AUTHOR]

Frisch-ring CdZnTe detectors have demonstrated both good energy resolution, < 1% FWHM at 662 keV, and good efficiency in detecting gamma rays, highlighting the strong potential of CdZnTe materials for such applications. We are designing a hand-held gamma-ray spectrometer based on Frisch-ring detectors at Brookhaven National Laboratory. It employs an 8 × 8 CdZnTe detector array to achieve a high volume of 19.2 cm³, so greatly improving detection efficiency. By using the front-end application-specific integrated circuits (ASICs) developed at BNL, this spectrometer has a small profile and high energy-resolution. It includes a signal processing circuit, digitization and storage circuits, a high-voltage module, and a universal serial bus (USB) interface. In this paper, we detail the system's structure and report the results of our tests with it. [ABSTRACT FROM AUTHOR]

Low dislocation density, high-purity, and low inclusion concentration Cd0.9Zn0.1 Te (CZT) and CdTe crystals were grown by a vertical Bridgman technique using in-house zone refined precursors. The grown crystals were sequentially processed using optimized chemo-mechanical processes to fabricate planar and Frisch collar detectors. Infrared transmission and scanning electron microscopy studies have shown that EIC grown CZT and CdTe crystals have significantly lower Te inclusions and defect densities than commercially available spectrometer grade crystals. The charge transport properties (electron and hole mobility-lifetime products, μτe & μτh) of various detectors have been evaluated by Hecht analysis. The detectors have been tested for spectral response using 59.5 and 662 keV γ-ray sources. The CZT detectors with planar electrodes showed 2.6% FWHM at 662 keV. By adding a Frisch collar, the detectors' spectra improved significantly. The Frisch collar detectors proved to be very promising for assembling large-area arrays with excellent energy resolution at relatively low manufacturing cost. [ABSTRACT FROM AUTHOR]