Ultrafast Decay, Ultrahigh Spatial Resolution, and Stable -CuI Single Crystal Treated by Iodine Annealing and SiO₂ Coating

The demand for scintillators with ultrafast decay times, high spatial resolutions, and high stabilities is increasing due to the development of ultrafast hard X-ray detection, hard X-ray imaging, and high-energy physics facilities. gamma-CuI single crystals, which exhibit ultrafast luminescence and high stopping power for hard X-rays, hold great promise for such applications. However, slow luminescence and poor stability caused by surface iodine deficiencies hinder the practical use of gamma-CuI. Herein, we treated a gamma-CuI single crystal by iodine annealing and SiO2 coating and investigated its crystal structure and luminescence properties in detail. Iodine annealing significantly enhanced the near-band-edge emission of the gamma-CuI crystal with an ultrafast decay time of less than 1 ns, while completely suppressing the slow luminescence. Moreover, the SiO2 film effectively prevented the oxidation and decomposition of surface iodine, leading to substantial improvement in luminescence stability. The gamma-CuI crystal demonstrated an ultrahigh spatial resolution of 1.5 mu m in X-ray imaging, highlighting its potential for ultrafast hard X-ray imaging applications. This study provides insight into the growth, optimization, and application of gamma-CuI crystals, advancing the field of scintillator materials.