The dissertation aimed to prepare thin films of tin oxide (SnO₂) and yttrium oxide (Y₂O₃) using the sol-gel and dip-coating techniques, and to investigate the effect of yttrium oxide concentration on the structural and morphological properties, as well as the optical band gap of tin oxide. The effect of these modifications on the sensing properties of the gas sensor toward oxidizing and reducing gases at room temperature was also investigated. In addition, the effect of different concentrations of silver (Ag) on the structure and properties of the prepared thin films was studied, as well as the effect of the optimum concentration on improving the optical band gap and gas-sensing performance.

The dissertation also included the characterization of the thin films using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), ultraviolet–visible spectroscopy (UV–Visible), and photoluminescence spectroscopy (PL) to investigate their structural, morphological, and optical properties.

The results demonstrated the successful preparation of thin films with nanostructured compositions, which directly affected the surface roughness and increased the surface area of the films, as well as their optical band gap. A significant improvement was observed upon the addition of silver, which contributed to enhancing the gas-sensing performance toward parts-per-million (ppm) concentrations of oxidizing and reducing gases at room temperature. This consequently contributes to reducing energy consumption owing to the lower operating temperature of gas sensors fabricated based on these films.

•  The most important recommendations of the study are:
  • Investigating the effect of doping with other materials on the sensing properties.
  • Investigating the effect of temperature and humidity on the gas-sensing behavior.
  • Evaluating long-term stability.
  • Investigating the variation in sensitivity with gas concentration.