Structural and optical properties of pure SnO2 and V2O5/SnO2 nanocomposite thin films for gas sensing application

Abstract

In this study, pure SnO2 and V2O5/SnO2 nanocomposite thin film NH3 sensors with varying V2O5 contents were successfully prepared by spray pyrolysis method. The prepared thin films were characterized by X-ray diffraction, Field emission scanning electron microscopy, Energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, stylus profilometry and Ultra violet–Visible and transmittance spectroscopies. NH3 gas sensing property was also studied. XRD results suggested that all the thin films exhibited a tetragonal rutile crystal structure, while the average crystallite size increases with V2O5 content. FESEM images of the thin films showed the presence of both nano and micro-sized grains in the range ~ 53–194 nm. EDX spectra confirmed the inclusion of V2O5 into the SnO2 matrix. The vibrational bands associated with the thin films were verified from the FTIR spectra. Thickness measurements revealed that the thickness increases with V2O5 content. Change in transparency and bandgap narrowing were also noticed from the transmittance and UV–Vis spectra. NH3 gas sensing measurements suggested that the transient resistance of V2O5/SnO2 thin film was lower than pure SnO2. Further, in the operating temperature 300 °C and 100 ppm NH3 gas, the sensor response of V2O5/ SnO2 thin film (99.13) is found to be higher than pure SnO2 thin film (92.34). Also, the response and recovery times of pure SnO2 thin film (30 and 44 s) are lower than V2O5/SnO2 thin film (39 and 180 s). These results indicate that V2O5/SnO2 thin film could serve as a suitable material for NH3 gas sensing application.