A Study of Morphological, Optical and Gas Sensing Properties for Pure and Ag Doped SnO2 Prepared by Pulsed Laser Deposition (PLD)

The pulsed laser deposition method, PLD, has been used in this project to deposit the pure SnO2 and the doped one with Ag at different concentrations (as a thin film) on Si (111) and glass. The aim was to study the influence of doping on surface morphology of the deposits materials using scanning electron microscope (SEM) and atomic force microscope (AFM). The resultant showed that there is a direct relationship between the grain sizes of the nanoparticles observed at the surface and doping concentration which means as the doping concentration increases there will be a similar enhancement in the grain size as well. Additionally, we were able to find that the best concentration of doping at ratio of 3%Ag: SnO2. Similarly, the RMS roughness showed a direct proportion with the doping concentration .It was equal to (11 nm) for 3%Ag: SnO2 thin films. Furthermore, we have also investigated the Optical Transmission Spectra of the samples. The characterisations of the gas sensing of these thin films were strongly influenced by the surface morphology. It has been also found that Ag doped nanocrystalline SnO2 gas sensing material was presented a better sensitivity compared to the pure SnO2 and this can be due to the distribution of Ag2O particles in the grain boundaries of nanocrystalline SnO2 and the formation of p–n heterojunction.