Stoichiometric Engineering for large-size CsPbBr 3 Crystal Growth and Gamma-Ray Detection Optimization

Abstract

CsPbBr 3 has been regarded as a promising alternative to the state-of-the-art CdZnTe for room-temperature semiconductor detectors. However, currently, high resolution γray detector is only achieved with CsPbBr 3 crystals of limited dimensions and efficiency, since the undesirable second phase precipitations. In this study, the highresistivity detector-grade CsPbBr 3 crystals are grown using the vertical Bridgman method by tailoring the stoichiometric ratio of the raw materials. To avoid the formation of unexpected secondary phases, a stoichiometric ratio with a 1.5% excess of CsBr is adopted, which minimizes the enrichment of PbBr 2 at the solid-liquid interface during growth. As a result, the CsPbBr 3 crystals exhibit a superior resistivity of 1.8×10 9 Ω•cm 2 and hole mobility-lifetime product of 1.71×10 -3 cm 2 •V -1 . Finally, the CsPbBr 3 ingots with diameters of 60 mm and lengths exceeding 90 mm are obtained. The resulting CsPbBr 3 planar detectors, with dimensions of 14×14×4 mm 3 , resolve the peaks of 137 Cs@662 keV and 241 Am@59.5 keV γ-rays with energy resolutions of 9.16% and 12.69%, respectively. This strategy on stoichiometric ratio tailoring in our work will pave the way for large detector grade CsPbBr 3 crystals in γ-ray detection.Wenjie Liu and Bangzhi Ge contributed equally to this work.