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Enhanced Sensing Performance of Sb-Doped Nanometer-Thin SnO 2 Films toward CO and NH 3 Gases

2023; American Chemical Society; Volume: 6; Issue: 9 Linguagem: Inglês

10.1021/acsanm.3c01032

2574-0970

Ramarajan Ramanathan, Selvakumar Nagarajan, Venkataramana Bonu, Priyanka Patel, Shubhangi Jamdar, Harish C. Barshilia, Ramesh Chandra Mallik,

Advanced Chemical Sensor Technologies

Thin film technology offered several possibilities and advancements in modern gas sensor devices. We have developed template-free, Sb-doped nanometer thin-SnO2 films for CO/NH3 gas detection using a facile spray technique on the glass substrates. Structural, surface, optical, and resistivity properties of as-deposited films were investigated as a function of film thickness for enhanced gas sensor performance. Structural analysis confirms tetragonal phase formation along with the texture behavior of the films. Increasing film thickness leads to an increase in the texture growth of the film, which can also impact gas sensing. As-deposited films display a polygon microstructure with dense film formation, leading to a large sensing surface. HR-TEM analysis confirms that Sb-doped nanometer-thin SnO2 (ATO) films have a relatively low crystallite size than pristine TO films. Pristine SnO2 (TO) film has better bandgap matching with bulk SnO2 samples. ATO thin films have relatively lower band gap values and decrease as a function of film thickness due to enhanced free carrier density upon Sb doping. To determine the best optimum condition, gas sensing analysis was investigated at different operating temperatures (150, 200, and 250 °C) for different gas concentrations (5 to 25 ppm). Designed TO and ATO film base sensors exhibit rectifying gas-sensing behavior, indicating the formation of a potential barrier across the film surface and metal (Au) interface. ATO film-based gas sensor devices showed enhanced response toward CO/NH3 gas detection compared to pristine TO thin film. Also, ATO thin films exhibited better stability and selectivity toward CO gas detection than NH3 gas. However, the ATO film with very low resistance below 1 kΩ is not able to be used as a gas sensor. Hence, the results obtained indicate the optimum resistive behavior of nanometer ATO films' applicability toward enhanced CO/NH3 gas detection.