BNL's Thallium Bromide Semiconductor Radiation Materials and Detectors Characterization Two overarching requirements of crucial importance for the commercial- and scientific establishment of semiconductor radiation detectors are: (1) exceptionally high-purity crystals with impurity concentrations less than 1 part-per-billion and (2) single crystals that are relatively free from subgrain boundaries, secondary phases, dislocations, and other electrically-active defects. BNL investigated the properties of thallium bromide (TlBr) material that affect its performance with the goal of increasing the material’s commercial viability for radiation detection applications. For this purpose, BNL used beamlines at the National Synchrotron Light Source, performing Micron-scale X-ray Detector Mapping, White Beam X-ray Diffraction Topography and Micron-scale X-ray Fluorescence. BNL applied these methods to the characterization of TlBr to improve the industry’s understanding of the material and lead to the production of improved instrumentation. With regard to TlBr material, BNL observed the electro-migration of Cu, Ag, and Au impurities that exist in positive-ion states in TlBr detectors under electric field strengths typically used for device operation. With regard to TlBr detectors, BNL applied an electrode design to accurately correct the response non-uniformities caused by crystal defects . This design can achieve improved energy resolution while using typical-grade, commercial crystals with relaxed quality requirements, thus reducing the overall cost of detectors. Additional characterization will be necessary to fully understand the structure and performance of TlBr with the ultimate goal to achieve the highest energy resolution. Our findings from past work will be presented along with our recommendations for additional investigation.
Year
2020
Abstract