关键词: 全无机钙钛矿CsPbBr₃; 坩埚下降法; 半导体核辐射探测器; γ射线探测; 载流子输运性能; 能量分辨率

Abstract: Semiconductor radiation detectors have broad and surging applications in homeland security， medical imaging， and fundamental scientific research. Recently， the all-inorganic perovskite CsPbBr₃ has attracted considerable attention owing to its suitable bandgap （~2.3 eV）， high effective atomic number （65.9）， high density （4.85 g·cm^-3）， high resistivity （>10⁹ Ω·cm）， and excellent carrier transport properties （μτ on the order of 10^-3 cm²·V^-1）， making it a promising candidate for next-generation room-temperature semiconductor radiation detectors. Specifically， CsPbBr₃ crystals can be synthesized via either solution-growth or melt-growth techniques. Solution-based methods are typically carried out at relatively low temperatures and feature simple fabrication procedures and low cost. However， the size of solution-grown CsPbBr₃ crystals is generally limited to the centimeter scale. In comparison， melt-growth techniques are currently the most widely used methods for producing large-size CsPbBr₃ crystals. Nevertheless， melt growth is typically carried out at high temperatures using high-purity raw materials. Moreover， due to the relatively low thermal conductivity of CsPbBr₃， together with the structural phase transitions during the cooling process， defects such as twins and cracks are readily generated， severely deteriorating the single-crystal quality and detector performance.In this work， the growth process of CsPbBr₃ crystals was systematically investigated using the vertical Bridgman method. Based on optimized growth parameters， including the temperature gradient and cooling rate， a high-quality large-volume CsPbBr₃ crystal with dimensions ofø40 mm×7 cm was successfully grown using zone-refined CsPbBr₃ polycrystals. The optical properties of the as-grown CsPbBr₃ crystals were systematically characterized. UV-Vis-NIR measurement revealed a high optical transmittance of up to 80% and a bandgap of 2.27 eV. Photoluminescence （PL） measurement showed a strong emission peak at 531 nm， while time-resolved photoluminescence （TRPL） spectra exhibited decay lifetimes of 2.26 and 38.62 ns， respectively. To evaluate the electrical properties， γ-ray detection performance， and charge transport properties， an asymmetric Au/CsPbBr₃/EGaIn planar device was fabricated. The CsPbBr₃ detector exhibited a high resistivity of up to 6.12×10⁹ Ω·cm determined by current-voltage （I-V） test. Owing to the asymmetric Schottky-type configuration， the dark current was effectively suppressed to 4.4 nA at -100 V， which was approximately two orders of magnitude lower than that measured at 100 V. In addition， the device exhibited a large ON/OFF ratio of 2 300 under a bias of -10 V using a white LED as the illumination source during current-time （I-t） test. The detector was subsequently evaluated using various γ-ray sources under a hole-dominant collection mode， achieving energy resolutions （ERs） of 10.0%， 5.5%， and 1.6% at room temperature for ²⁴¹Am （59.5 keV）， ⁵⁷Co （122 keV）， and ¹³⁷Cs （662 keV） γ-rays， respectively. Carrier transport properties， particularly high carrier mobility and long carrier lifetime， are critical for improving charge collection efficiency and radiation detection performance. Using a ²⁴¹Am γ-ray source， the hole mobility of CsPbBr₃ was determined to be 24.41 cm²·V^-1·s^-1 via time-of-flight （TOF） measurement， while the hole mobility-lifetime product was extracted to be 4.17×10^-3 cm²·V^-1 based on the Hecht equation. This work presents a reliable growth process for producing high-quality large-volume perovskite CsPbBr₃ with superior radiation detection performance， which may facilitate their scalable fabrication and practical applications.

Key words: all-inorganic perovskite CsPbBr₃; Bridgman method; semiconductor radiation detector; γ-ray detection; carrier transport property; energy resolution