Impact of Cu doping on morphology, structural and optical characteristics of SnO₂ thin films prepared by spray pyrolysis

Tin dioxide thin films prepared by spray pyrolysis and doped with Cu atoms were studied. The influence of Cu doping levels (from 1.0 to 5.5at%) on the morphology, structural, and optical characteristics of the films was investigated. X-ray diffraction (XRD) patterns related to a tetragonal SnO₂ crystalline structure have been detected in all the studied films. With increasing copper content, XRD peaks shifted towards the higher angles, along with an increase in the optical bandgap in the films and a reduction of the grain sizes. A transparency of 70–80% in the visible spectral range was detected in the studied films. Furthermore, an increase in the bandgap energy from 3.70 eV to 4.55 eV was observed in the films owing to the reduction of SnO₂:Cu crystal lattice parameters with increasing Cu contents. The variations of the structural and optical parameters of the SnO₂ films upon Cu doping were analyzed and discussed.