Preparation of SnO and SnO2 thin films: Influence of annealing on structural, morphological, and optical properties

Tin oxide (SnO/SnO2) thin films with a thickness of about 400 ± 2nm were fabricated on glass substrates using physical vapor deposition (PVD). To assess the effect of thermal treatment, the deposited films were subsequently annealed at 200 °C and 300 °C. X-ray diffraction (XRD) measurements revealed the simultaneous presence of tetragonal SnO and orthorhombic SnO2 phases in all specimens. After annealing, the diffraction peaks became more intense and narrower, reflecting enhanced crystallinity and grain development. Atomic force microscopy (AFM) showed a marked reduction in root-mean-square (RMS) surface decrease after anealing, accompanied by an increase in mean grain size from (49 – 62) nm. UV–visible spectroscopy indicated high optical transparency (>75%) throughout the visible spectrum. The optical constants (refractive index, absorption index and extinction index) were calculated. The optical band gap chang after annealing.