Enhanced Electrical and Nuclear Radiation Detection Performance in BiI3 Wide Bandgap Semiconductor Detectors

BiI₃ is a wide band-gap compound semiconductor with a high effective atomic number that is anticipated to exhibit higher detection efficiency than other compound semiconductors such as HgI_2, PbI₂, and CdZnTe.  This makes BiI₃ of particular interest for moderate and high energy gamma-ray detection applications.  However, the low resistivity of BiI₃ results in high leakage currents and degrades the electrical properties and detecting performance of the detectors.  Here we show that the main reason for the low resistivity in BiI₃ is due to the high volatility of iodine and the high concentration of intrinsic Schottky defects.  Furthermore, we will discuss novel defect engineering strategies that successfully mitigate the obstacles associated with iodine vacancies in the material.  Density functional theory (DFT) calculations, as well as experimentally measured electrical properties, and radiation response will be presented for undoped and Sb-doped BiI₃ (SBI) single crystals grown via the vertical Bridgman growth technique.  Most importantly, we will demonstrate the first ever recorded gamma-ray spectrum using BiI₃-based detectors.