High-quality, large (10 cm long and 2.5 cm diameter), nuclear spectrometer grade Cd 0.9 Zn 0.1 Te (CZT) single crystals have been grown by a controlled vertical Bridgman technique using in-house zone refined precursor materials (Cd, Zn, and Te). A state-of-the-art computer model, multizone adaptive scheme for transport and phase-change processes (MASTRAP), is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in the as-grown CZT crystal and optimize the thermal profile. The model accounts for heat transfer in the multiphase system, convection in the melt, and interface dynamics. The grown semi-insulating (SI) CZT crystals have demonstrated promising results for high-resolution roomtemperature radiation detectors due to their high dark resistivity (r % 2.8 3 10 11 V cm), good charge-transport properties [electron and hole mobility-lifetime product, mt e % (2-5) 3 10 ÿ 3 and mt h % (3-5) 3 10 ÿ 5 respectively, and low cost of production. Spectroscopic ellipsometry and optical transmission measurements were carried out on the grown CZT crystals using two-modulator generalized ellipsometry (2-MGE). The refractive index n and extinction coefficient k were determined by mathematically eliminating the ;3-nm surface roughness layer. Nuclear detection measurements on the single-element CZT detectors with 241 Am and 137 Cs clearly detected 59.6 and 662 keV energies with energy resolution (FWHM) of 2.4 keV (4.0%) and 9.2 keV (1.4%), respectively.
Low-noise, voltage-sensitive preamplifiers were designed with pole-zero cancellation in the feedback circuit to stabilize the output baseline against variations in the mean rate and amplitude of random signals. Compared to conventional feedback and subsequent pole-zero cancellation, this method of baseline stabilization increased the fraction of signals transmitted without distortion by preamplifier saturation from 50 to > 99% for steplike input signals of 240 m V amplitude occurring randomly at a mean rate of 10 4 signals/sec.
In the above mentioned article, two references were regrettably omitted from the final paragraph in the first column of page 1253, and inappropriately similar wording to the original references was used. The authors sincerely apologize to the authors of the references and the journal readership for this error. Please replace the passage ''Notably, the CZT crystal… …growth of other semiconductors.'' with ''CZT melt exists as a semiconductor 1 with the Prandtl number of Pr ¼ 0.41, which is a few orders of magnitude larger than that of most semiconductor materials, such as Si, GaAs, and InP. The Pr ¼ 0.41 causes a strong coupling between thermal and momentum transport, which leads to instabilities in the growth of CZT crystal.'' 2
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