Bismuth tri-iodide radiation detector development

Azaree T. Lintereur; Wei Qiu; Juan C. Nino; James E. Baciak

doi:10.1117/12.825037

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17 September 2009 Bismuth tri-iodide radiation detector development

Azaree T. Lintereur; Wei Qiu; Juan C. Nino; James E. Baciak

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Proceedings Volume 7449, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XI; 74491M (2009) https://doi.org/10.1117/12.825037
Event: SPIE Optical Engineering + Applications, 2009, San Diego, California, United States

Abstract

Bismuth tri-iodide (BiI₃), a wide band-gap semiconductor, demonstrates many of the material properties necessary for high resolution room temperature gamma-ray spectroscopy. These material properties include high density, large bandgap, and high atomic number. The theoretical intrinsic photopeak efficiency of BiI₃ is approximately 2-3 times higher than CdZnTe over the range of 200-3000 keV. BiI₃ has a theoretical intrinsic photopeak efficiency of 19% at 662 keV, compared to CdZnTe which has a theoretical intrinsic photopeak efficiency of 13% at 662 keV. A modified vertical Bridgman growth method is being used to grow large, greater than 100 mm³, single BiI₃ crystals. Growth parameter optimization has demonstrated that single crystals can be obtained with temperature gradients of 10°/cm or 15o/cm and a growth rate of 0.5 mm/hr, or with a temperature gradient of 10o/cm and a growth rate of 1 mm/hr. Polycrystalline material results from all other growth parameter combinations. X-ray diffraction spectra are used to determine if the crystals are single crystals or polycrystalline. UV-VIS spectra analysis has revealed that the band-gap of BiI₃ is 1.72 eV. The resistivity of the crystals has been determined by generating I-V curves to be on the order of 10⁸-10⁹ Ω-cm. Zone refining is being performed to increase the purity of the starting material and the resistivity of the crystals. Detectors have been fabricated with both gold and palladium electrodes.

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Azaree T. Lintereur, Wei Qiu, Juan C. Nino, and James E. Baciak "Bismuth tri-iodide radiation detector development", Proc. SPIE 7449, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XI, 74491M (17 September 2009); https://doi.org/10.1117/12.825037

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