Photoluminescence enhancement in cuprous iodide crystalline thin films achieved through repeated step-growth and rapid thermal annealing

In this study, the growth and annealing of cuprous iodide (CuI) films using a repeated step-growth method followed by rapid thermal annealing between layers were investigated. The results showed that the repeated annealing step-grown CuI thin films displayed enhanced photoluminescence (PL) compared to as-deposited CuI thin films without stepped growth. Each step-grown layer was thermal evaporated and then subjected to rapid thermal annealing, leading to the examination of the structural, optical, and electrical properties of the thin films. At room temperature, it was found that the repeated annealing step-grown CuI films displayed stronger PL emissions in the violet region compared to GaN layers. Additionally, a significant increase in coverage over 50 µm diameter was observed due to grain merging and void filling through the repeated annealing step-growth process. These findings indicate that direct thermal deposition and heat treatment can be a practical method for growing high-quality p-type polycrystalline CuI films. The process provides uniform crystalline CuI films with reduced number of voids on the surface and high hole mobility, which is useful for optoelectronic thin film devices.