Nanostructure of Cu₂O/SnS Layers Thermally Evaporated: Annealing Effect on Structural and Optical Properties

Thin film techniques and layers are essential in many industrial applications such as solar cells, gas sensors, photodetectors, etc. In this study, the impact of the annealing process on the structural and optical characteristics of tin sulfide and cuprous oxide (Cu₂O NPs/SnS) thin films prepared by thermal evaporation technique onto glass substrates, then annealed at 200 °C was studied to a candidate the layers for solar cell fabrication. X-ray diffraction, surface morphology, and UV–visible measurement characterized the films. After annealing, the average crystal size of Cu₂O/SnS nanostructure films decreased from 14 to 12 nm, while the dislocation and micro-strain increased. The SEM images show a uniform and homogeneous distribution after the annealing process and EDX analysis confirmed the elemental stoichiometry of the films. The obtained values of average roughness increased from 0.458 to 0.678 nm, and the root mean square increased from 0.579 to 0.875 nm. The evaluated energy gap of thin films was 1.75 eV for as-deposited and 1.8 eV for annealed films. The surface homogeneity and appropriate energy band gap refer to suitable films for optoelectronics applications.