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 and CdTe hybrids have proven to be valuable materials for high- resolution, high detection-efficiency, and high-count rate room-temperature radiation detectors that can achieve resolutions of <1% full-width half maximum (FWHM) at 662 keV. These materials offer superior efficiency and image quality in nuclear safeguards, homeland security, nuclear medicine, and x-ray imaging. Recent advancements in the Accelerated Crucible Rotation Technique by Modified Vertical Bridgman (ACRT-MVB) growth method developed at Washington State University (WSU) allows for CZT and alike materials to be grown 10 – 20 faster 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. The ACRT-MVB growth method reduces or eliminates the main cost drivers for CZT, growth speed and post-processing. In Phase 1, crystal seeding was demonstrated in the ACRT-MVB system, resulting in increased single-crystal yields and detector performance. Large single-crystal devices, up to 30 mm long, were fabricated and tested consistently at <2.5% FWHM at 662keV with some measuring 1.1% FWHM with no electronic correction or cooling. In Phase II, the technology will be transferred from WSU into commercial production at RDT. WSU will further develop seeded growth in the ACRT-MVB system and RDT will establish an industrial-grade ACRT-MVB furnace at RDT capable of 4-inch diameter ingot growth. RDT will process 4-inch CZT/CdTe wafers using standard VLSI processing techniques providing a rapid turnaround from crystal-growth into devices and to the customer. The markets for CZT and CdTe-hybrid gamma-ray spectrometers and imagers are vast, particularly for national security, medical/diagnostic imaging, baggage scanning/imaging and solar photovoltaics. Currently, the United States does not have a US-based vender to provide spectroscopic-grade CZT/CdTe materials to satisfy commercial needs, particularly for national security applications. Not only will the success of this technology transfer establish a US vendor for CZT and CdTe material supply, the benefit to the market will be significant with a reduction of spectroscopic- grade material costs (>3x) by improving yield and reducing main cost drivers. 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, low-cost, and consistent high-performance material available commercially, (2) the US government will have a US vender from which CZT can be purchased for national 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 to further advance the technology state-of-the-art.