Growth and characterization of CsCu2I3 single crystal for X-ray detection with a modified Bridgman method

Lead-free copper halide CsCu₂I₃ crystal is a potential detector material for high-energy rays because of its wide band gap (3.54 eV), large relative molecular mass, strong absorption of high-energy rays, and low hygroscopicity in the air environment. In this study, a single crystal of CsCu₂I₃ with 27 mm in diameter and 55 mm in length, the largest reported size, was successfully grown using a modified Bridgman method. It has a high degree of transparency and the transmittance is more than 90 % in the range of 4∼22 μm. An Au/CsCu₂I₃ SC/Au detector was fabricated and tested, showing a resistivity of 1.08 × 10¹¹ Ω cm. The X-ray responsivity of CsCu₂I₃ single crystals was investigated using a corresponding high-energy ray detector. The device exhibited a fast response time (<0.1 s), a high switching ratio (180), and a response sensitivity of 77.61 μC·Gy_air⁻¹·cm⁻¹ under an electric field strength of 10 V mm⁻¹. The successful growth of such a large CsCu₂I₃ single crystal demonstrates the potential for producing high-quality single crystals, which are essential for practical applications.