Structural, optical and morphological properties of Ta₂O₅/SnO₂ nanocomposite thin film prepared by spray pyrolysis method

The present paper reports the structural, morphological and optical characterizations of Ta₂O₅/SnO₂ thin films prepared on glass substrate by spray pyrolysis technique. The effect of Ta₂O₅ content on the structural, morphological and optical properties of the prepared thin films was investigated. X-ray diffraction (XRD) result indicated that pure SnO thin film has tetragonal crystal structure. It is observed that the tetragonal structure of SnO transformed to rutile phase of SnO₂, when the content of Ta₂O₅ is increased. The average crystallite size of the thin films calculated using Debye–Scherrer formula is in the range 51–71 nm. Field Emission Scanning Electron Microscope (FESEM) images of both pure SnO and Ta₂O₅–SnO₂ nanocomposite thin films have grain size in the range ~ 68–98 nm. Fourier transform infrared Spectrophotometer (FTIR) study reveals that the vibrational modes related to SnO₂ and Ta₂O₅ are available and ascertains the formation of nanocomposite. Energy-dispersive X-ray (EDX) spectra indicate the existence of Tantalum signals along with the signals of tin and oxygen in the nanocomposites. UV–Vis absorbance spectra convey that the absorbance edge red shifts towards longer wavelength region with an increase in Ta₂O₅ content, which is a signature of band gap narrowing. Further, the optical band gap decreases from 2.25 eV to 1.95 eV, with an increase in Ta₂O₅ content. This band gap narrowing feature existed in the nanocomposite could be effectively exploited for optoelectronic devices.