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Description
All-inorganic CsPbBr3 single crystals are promising for X/γ-ray detection owing to their excellent carrier transport properties and room-temperature detection capability. However, processing-induced surface damage and bulk impurities can compromise device performance, and their effects on carrier transport and γ-ray detection remain to be systematically clarified. Herein, surface-state engineering and bulk impurity control were systematically investigated to address this challenge. A controlled stepwise polishing strategy was proposed for surface-state engineering. By this strategy, the surface roughness was decreased from approximately 20 to 2.8 nm. The surface damage layer was reduced from 3 μm to 110 nm, and the effective trap density was lowered by a factor of approximately 4.5. Consequently, the dark current of the devices fabricated on the same crystal decreased from 210 to 30.3 nA, and the energy resolution for 662 keV 137Cs γ-rays improved from 22.8% to 6.4%. Furthermore, an iterative dynamic zone-refining strategy was proposed to grow high-quality CsPbBr3 single crystals at a growth rate of 25 mm h−1, directly yielding low-impurity crystals after 40 passes. The middle region exhibited a minimum total impurity concentration of 6.1 ppm, with a hole mobility–lifetime product (μhτh) of 1.2 × 10−3 cm2 V−1. The fabricated Au/CsPbBr3/In planar detectors achieved an energy resolution of 3.4% for 662 keV 137Cs γ-rays at room temperature. Segregation-coefficient analysis and density functional theory (DFT) calculations identified Ti and Cu as key deep-level impurities limiting carrier transport. These results indicate that surface damage removal and bulk impurity control suppress surface leakage and improve carrier transport, respectively, jointly enhancing the γ-ray detection performance of CsPbBr3 single crystals. This work provides experimental evidence and design guidance for surface-state engineering and crystal growth of high-resolution X/γ-ray detector materials.
