Characterization of Traveling Heater Method (THM) Grown ${\hbox{Cd}}_{0.9}{\hbox{Zn}}_{0.1}{\hbox{Te}}$ Crystals

Abstract

High-performance semi-insulating single crystals of n-type Cd 0 9 Zn 0 1 Te (CZT) were grown using the traveling heater method (THM). X-ray and -ray detector configurations fabricated from this material have a room-temperature mean energy resolution of 4.3% FWHM for a 57 Co source (122 keV) and uniform pixel-to-pixel response on monolithic 20 20 5 mm 3 pixellated detectors. Energy resolution of 1% FWHM for 137 Cs (662 keV) has been measured on virtual Frisch-grid 4 4 11 mm 3 devices useful for homeland security applications. Additional characterization techniques including mobility-lifetime measurements, infrared microscopy, X-ray topography, and OPTICAL Deep Level Transient Spectroscopy (ODLTS) have demonstrated the superior quality of this THM CZT.

Characterization of large cadmium zinc telluride crystals grown by traveling heater method

“…2,3 This characteristic is again measured in the postannealed 12 mm wafer materials. IR analysis, measured at LBNL, revealed a low density of precipitated/inclusion.…”

“…An energy resolution, full width at half maximum ͑FWHM͒, of Ͻ1% was measured on a virtual Frisch-Grid Device. 2,3 However, for practical purposes, thicker detectors are needed in the higher energy gamma range such as gamma spectroscopy and standoff detection for homeland security. In parallel, larger area crystals are needed to ultimately provide the required larger volume.…”

“…3 represent the amount of Te precipitate/inclusion in the sample with particle size less than 5 m. The advantages of small size, low concentration of Te inclusions/precipitates in CZT thick detectors have also been reported previously. 2 It is important to mention that spatial resolution of the x-ray mapping system plays a crucial role in this kind of study. By using low-and high-contrast x-ray mappings, researchers at BNL have been able to reveal Te inclusions/ precipitates of sizes less than 5 m where they have seen under high-contrast only.…”

“…Recently, it was shown that the traveling heater method ͑THM͒ is a practical approach to crystal growth supporting volume production of CZT radiation detectors for both medical imaging and homeland security applications. 2,3 Large-area monolithic CZT detectors that are produced by THM method provide excellent performance. Thicker detectors 2,3 have also been shown to function well.…”

“…2,3 Large-area monolithic CZT detectors that are produced by THM method provide excellent performance. Thicker detectors 2,3 have also been shown to function well. This level of performance has been restricted to smaller area single-channel detectors in the form of Frisch-Grid devices.…”