X-ray excited luminescence of CuI thin films fabricated by iodine solution method

CuI is considered as a potential candidate for fast scintillator material due to the fast decay time. However, the ever-reported CuI scintillator usually demonstrates a more intensive deep-level emission with the decay time as long as 2.82 mu s, which is unfavorable for the application as a fast scintillator material. In present work, gamma-phase CuI were synthesized by iodizing Cu thin films in iodine solution at room temperature. An apparent near bandedge emission (NBE) is observed both in photoluminescence and X-ray excited luminescence spectra. By analyzing the variation of the relative intensity ratio of the sub-peaks composing NBE against different fabrication conditions, it can be deduced that Cu vacancy and surface chemisorbed iodine are responsible for the above luminescence behavior. It is hoped that these findings may boost the exploration of CuI thin films as fast scintillator materials.