Stoichiometric engineering for large-size CsPbBr3 crystal growth and gamma-ray detection optimization

Abstract

CsPbBr₃ is regarded as a promising alternative to state-of-the-art CdZnTe for room-temperature semiconductor detectors. However, currently, a high-resolution γ-ray detector is only achieved with CsPbBr₃ crystals and shows limited dimensions and efficiency due to the formation of undesirable secondary-phase precipitations. In this study, high-resistivity detector-grade CsPbBr₃ crystals are grown using the vertical Bridgman method by tailoring the stoichiometric ratio of the raw materials. To avoid the formation of undesired secondary phases, a stoichiometric ratio with a 1.5% excess of CsBr is adopted, which minimizes the enrichment of PbBr₂ at the solid–liquid interface during growth. As a result, the CsPbBr₃ crystals exhibit a superior resistivity of 1.8 × 10⁹ Ω cm and a hole mobility-lifetime product of 1.71 × 10⁻³ cm² V⁻¹. Finally, CsPbBr₃ ingots with diameters of 60 mm and lengths exceeding 90 mm are obtained. The resulting CsPbBr₃ planar detectors, with dimensions of 14 × 14 × 4 mm³, resolve the peaks of ¹³⁷Cs@662 keV and ²⁴¹Am@59.5 keV γ-rays with energy resolutions of 9.16% and 12.69%, respectively. The proposedstrategy of tailoring the stoichiometric ratio in our work will pave the way for large detector-grade CsPbBr₃ crystals in γ-ray detection.