Influence of substrate temperatures on the microstructural, morphological, and optoelectronic characteristics of Cu₃N/ITO thin films intended for solar cell applications

Solar cells are crucial for renewable energy, with indium tin oxide (ITO) commonly used as a window layer. Copper nitride (Cu₃N) is a promising material, yet research on both materials together is scarce. This study investigates the influence of substrate temperatures on the properties of Cu₃N/ITO thin films, a critical factor for solar cell efficiency. Cu₃N thin films were deposited onto ITO substrates using rf magnetron sputtering in an argon/nitrogen atmosphere at substrate temperatures ranging from room temperature (RT) to 150 °C. We found that increasing the substrate temperature significantly enhanced the microstructural, morphological, and optoelectronic properties of the Cu₃N/ITO films. XRD analysis revealed a polycrystalline nature with a cubic phase structure, and the average crystallite size increased from 17 nm (RT) to 37 nm (150 °C). SEM images showed a corresponding change in the surface morphology with increasing substrate temperatures. The optical properties of the films were studied in a range between (300 to 2500 nm) using UV–Vis-NIR spectroscopy, which showed a decrease in the optical energy gap from 2.62 eV (RT) to 2.23 eV (150 °C), indicating a tunable band structure. Additionally, optoelectronic properties containing optical conductivity, electrical conductivity, optical carrier concentrations, optical mobility, refraction loss, and optical resistivity were significantly affected by substrate temperature. Findings highlight the crucial influence of substrate temperatures and offer substantial potential for improving the efficiency of Cu₃N/ITO-based solar cells.