Overcoming Mobility Lifetime Product Limitations in Vertical Bridgman Production of Cadmium Zinc Telluride Detectors
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Cadmium zinc telluride (CZT) possesses excellent material properties for a wide range of applications where room temperature operability, durability, and high efficiency are required. However, because CZT is a challenging material to produce in useful quantities, the growth and fabrication costs have remained high, creating an economic challenge for vendors. While the traveling heater method (THM) is the predominant means of commercial CZT crystal growth, the vertical Bridgman method (VB) is an attractive alternative due to its relatively fast growth rate. However, VB grown CZT has yet to compete with THM grown CZT, particularly in terms of charge collection efficiencies, where the charge collection efficiency is characterized by the single carrier electron mobility lifetime (μτe) product. Despite efforts to overcome this discrepancy, the μτe product in VB grown CZT has remained an order of magnitude lower than THM. Eliminating this difference would bring VB one step closer to outpacing THM in terms of economic feasibility. This paper discusses the development of a unique technique that combines the advantages of both growth methods to better understand this discrepancy and the underlying mechanisms behind it. CZT ingots were grown from melt via VB with highly off-stoichiometric concentrations of tellurium (Te). Melt mixing via accelerated crucible rotation (ACRT) was applied to compensate for any negative effects associated with off-stoichiometry, i.e. flux inclusions. CZT material has been produced at growth rates commensurate with VB (one ingot/week) and with charge collection efficiencies commensurate with THM (mid 10−2 cm2/V) in long bars typical of commercial applications.
KeywordsDetectors mobility lifetime product vertical Bridgman impurities ACRT
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This work was partially supported by the National Nuclear Security Administration (NNSA) under Grant DE-NA0002565 U.S. Department of Energy and by the Center for Materials Research, Washington State University.
- 7.R. Triboulet and P. Siffert, CdTe and Related Compounds; Physics, Defects, Hetero- and Nano-Strucutres, Crystal Growth, Surfaces and Applications Part II Crystal Growth, Surfaces and Applications (Amsterdam: Elsevier, 2010).Google Scholar
- 8.J. McCoy, Implementation of Accelerated Crucible Rotation in Electrodynamic Gradient Freeze Method for Highly Non-stoichiometric Melt Growth of Cadmium Zinc Telluride Detectors (Pullman: Washington State University, 2018).Google Scholar
- 21.Glow discharge mass spectrometry (GDMS) analysis—National Research Council Canada (n.d.).Google Scholar
- 28.US7067008B2 (2003).Google Scholar
- 29.C. Szeles, Private Communication (2017).Google Scholar
- 32.CMR, Internal Communication (2019).Google Scholar