Investigation of Lead-Free Inorganic Perovskite for Gamma-Ray Detection Applications

Due to the unique crystal structure, the inorganic perovskites such as CsPbBr₃ are promising for ambient-temperature radiation detectors. Perovskites have a wide bandgap, high mobility-lifetime product, low defect densities, and long-term stability making these materials promising for radiation detection applications. CsPbBr₃, however, has complicated crystal growth conditions such as phase transformations, making it difficult to control the temperature gradient using Bridgman method, and possibly causing degradation of detector performance due to electric defects that disturb photogenerated carriers hopping. The Cs₃Bi₂I₉ (CBI) lead-free perovskite is a candidate for the radiation detector material that allows the control of crystal design with a stable phase transformation stabilizing the crystal structure. In this report, the synthesis of CBI crystals using Bridgman method was studied. The approach utilized computer control of temperature gradient between hot and cold zones, cooling rate, and a vertical translation of the vacuum-sealed quartz tube with the CBI powder. The characteristics of Cs₃Bi₂I₉ crystals will be discussed. The grown crystals were characterized using photoluminescence (room temperature and cryogenic), optical and scanning electron microscopy. We will also provide data on the compositional uniformity via XRD, EDS and SIMS techniques. Electrical characterization of the samples was performed for IV analysis.