A highly sensitive and room temperature ethanol gas sensor based on spray deposited Sb doped SnO2 thin films

Abstract

A room temperature ethanol gas sensor designed using antimony (Sb)-doped tin dioxide (SnO₂, ATO) nanostructure thin films was prepared via the chemical spray pyrolysis method as a function of Sb concentration (0, 2, 4, 6, and 8 wt%) at 420 °C. Structural, surface, optical, electrical, and temperature-dependent resistance studies were carried out using XRD, FESEM, UV-visible, and four-probe electrical resistivity techniques. Structural and surface microstructure analysis of the films confirms the nanostructure formation. Optical band gap and electrical resistivity studies demonstrate that the n-type conducting behavior of the films increased upon Sb doping. Temperature-dependent sheet resistance analysis confirms that ATO thin films exhibit maximum resistance stability up to 350 °C. The sensitivity of the fabricated ATO sensors strongly depends on the surface structure of the films, and the adsorbed gas molecules cause a change in the resistance of the films. A significant improvement was observed in the recovery and response times of the sensors as a function of Sb-doping content and ethanol exposure level. The maximum ethanol response achieved in the 6 wt% Sb-doped SnO₂ (ATO6) film was 842% for 50 ppm with a response and recovery time of 259/214 s, respectively. Hence, the ATO6 film exhibited a better sensing performance towards ethanol sensing applications.