Commercialization of the Rapid-Production Growth Method for Affordable Cadmium Zinc Telluride (CZT) Semiconductor

Reduction of the reliance of high-activity commercial and industrial radioactive sources is a nonproliferation goal. The Office of Proliferation Detection is interested in developing replacements for radiological sources to promote the adoption of non-radioisotopic alternative technologies where technically, operationally, and economically feasible. The goal of the DOE in reduction of the reliance on high-activity commercial and industrial radioactive sources in nonproliferation, can be better reached by increasing the detection efficiency and efficacy of radiation detection systems that utilize these sources, consequently reducing the required source activity. CZT has proven to be a valuable material for high-resolution, high detection-efficiency, room-temperature radiation detector that can achieve a resolution of <1% full-width half maximum (FWHM). The high spatial and energy resolution of CZT, compared to that of scintillators, offers superior efficiency and image quality in Nuclear safeguards, Home-land security, Nuclear medicine & X-ray imaging applications. Recent advancements in the Accelerated Crucible Rotation Technique by Modified Vertical Bridgman (ACRT-MVB) growth method developed at Washington State University by Dr. K. Lynn allows for CZT and alike materials to be grown at 10 – 20 faster growth rates than the current state-of-the-art at equal performance. At price points currently between $1500 - $2000 / cm3 for spectroscopic grade CZT, manufactures of radioisotope identifiers have resorted to inferior performance devices such as scintillators. The ACRT-MVB growth method for CZT is fast and does not required post- growth processing – the two major components that drive up the material cost. We see a 3x reduction in cost in the final CZT device with this new growth method. In Phase 1, it is proposed to begin the technology transfer of the ACRT-MVB for growing CZT materials into commercial production. This process will begin with identifying an optimal thermal profile, rotation profile and acceleration profile for a repeatable and scalable process for the growth of spectroscopic-grade CZT material. A total of 4 growths at 60-mm diameter, 3-inch long ingots will direct the team into optimization of the growth parameter of scale-up tasks in Phase II. These ingots will be processed into devices, characterized for ingot yield, resistivity, mobility-lifetime, and spectral resolution to validate the growth processes.CZT has a vast number of applications including gamma-ray spectrometers for radiation detectors, medical imaging, x-ray imaging and many others. Companies growing CZT material and manufacturing devices have come and gone in recent years leaving not a single United States vender to provide high-quality material to satisfy commercial needs. As a result, the US government does not have a US vender from which the material can be purchased for national security applications (US government prefers to purchase from US venders). The markets for CZT and related CdTe devices are vast, particularly for national security, medical/diagnostic imaging and solar. The fruition of this project will be the significant reduction (>3x) of industrial-grade material costs by increasing the yield, reducing the growth time, and eliminating post-growth anneal treatments currently used by industry. With the fast production time and high-performance of the CZT produced in this effort, (1) the CZT market will finally have a fast turnaround time and consist high-performance material that be obtained, (2) the US government will have a US vender from which CZT can be purchased for homeland security applications, and (3) US small business will have an affordable, high-performance CZT material that can be obtained for niche radiation detection and imaging instruments and other applications.