Control of Optical Absorption and Emission of Sputtered Copper Iodide Thin Films

Optical absorption and emission spectra are the important quantifiable properties for CuI as a promising optoelectronic material. Previous research on the sputter deposition of CuI focuses on room-temperature growth. Herein, the effect of growth temperature on the selected optical features of sputtered CuI thin films is investigated. An enhanced visible light transparency and a steeper absorption edge are achieved for CuI thin films by optimizing the growth temperature. The PL intensity ratio of free exciton to defect-related emission increases with increasing substrate temperature. These results suggest a strategy of growth temperature optimization for the enhanced absorption and emission of CuI for advanced optoelectronic applications.