Abstract
X- and gamma-ray detectors have broad applications ranging from medical imaging to security, non-proliferation, high-energy physics and astrophysics. Detectors with high energy resolution, e.g. less than 1.5% resolution at 662 keV at room temperature, are critically important in most uses. The efficacy of adding selenium to the cadmium zinc telluride (CdZnTe) matrix for radiation detector applications has been studied. In this paper, the growth of a new quaternary compound Cd0.9Zn0.1Te0.98Se0.02 by the Traveling Heater Method (THM) is reported. The crystals possess a very high compositional homogeneity with less extended defects, such as secondary phases and sub-grain boundary networks. Virtual Frisch-grid detectors fabricated from as-grown ingots revealed ~0.87–1.5% energy resolution for 662-keV gamma rays. The superior material quality with a very low density of defects and very high compositional homogeneity heightens the likelihood that Cd0.9Zn0.1Te0.98Se0.02 will be the next generation room-temperature detector material.
Highlights
Radiation detectors are critically needed in applications of medical imaging, security, non-proliferation, astrophysics and high-energy physics[1,2,3,4,5,6,7]
Virtual Frisch-grid CZTS detectors were fabricated from as-grown CZTS crystals; outstanding energy resolutions of ~0.87% at 662 keV were achieved without reliance on pulse-processing algorithms to correct for electron trapping
Selenium was effective in modifying the segregation coefficient of Zn, resulting in higher compositional homogeneity along the length of ingots as opposed to cadmium zinc telluride (CdZnTe)
Summary
Radiation detectors are critically needed in applications of medical imaging, security, non-proliferation, astrophysics and high-energy physics[1,2,3,4,5,6,7]. To produce detectors at low cost, materials ought to be produced with high production yield, requiring high compositional uniformity in the as-grown materials To meet these challenges, researchers have been exploring suitable radiation detector materials for more than four decades. The production yield of CZT suffers from the compositional inhomogeneity, while the secondary phases and the sub-grain boundary networks severely affect the charge collection and degrade the spectral response[16,17] These defects result in the high cost of CZT materials and limit the widespread deployment of the technology. The main detriment of THM-grown CZT ingots is that wafers need post-growth annealing to achieve detector-grade quality[18] This additional process further increases the production cost of the material. We can successfully eliminate the need for a post-growth annealing process as used extensively for THM-grown CZT, while achieving excellent transport properties
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