Influence of Mg Doping Levels on the Sensing Properties of SnO2 Films

Abstract

This work presents the effect of magnesium (Mg) doping on the sensing properties of tin dioxide (SnO2) thin films. Mg-doped SnO2 films were prepared via a spray pyrolysis method using three doping concentrations (0.8 at.%, 1.2 at.%, and 1.6 at.%) and the sensing responses were obtained at a comparatively low operating temperature (160 °C) compared to other gas sensitive materials in the literature. The morphological, structural and chemical composition analysis of the doped films show local lattice disorders and a proportional decrease in the average crystallite size as the Mg-doping level increases. These results also indicate an excess of Mg (in the samples prepared with 1.6 at.% of magnesium) which causes the formation of a secondary magnesium oxide phase. The films are tested towards three volatile organic compounds (VOCs), including ethanol, acetone, and toluene. The gas sensing tests show an enhancement of the sensing properties to these vapors as the Mg-doping level rises. This improvement is particularly observed for ethanol and, thus, the gas sensing analysis is focused on this analyte. Results to 80 ppm of ethanol, for instance, show that the response of the 1.6 at.% Mg-doped SnO2 film is four times higher and 90 s faster than that of the 0.8 at.% Mg-doped SnO2 film. This enhancement is attributed to the Mg-incorporation into the SnO2 cell and to the formation of MgO within the film. These two factors maximize the electrical resistance change in the gas adsorption stage, and thus, raise ethanol sensitivity.

Controlling the structure and composition of SnO2-based thin film with reactive sputtering to improve the sensitivity of semiconductor CO2 sensor

“…The figure displays lines before the peak separation in red, the overall fitting result in gray, the fitting results for O-Sn 4+ in purple, the fitting results for O-Sn 2+ , the fitting results for V o in purple, and the fitting results for O cem in green. The energy difference between O-Sn 2+ and O-Sn 4+ , O-Sn 2+ and V o , and O-Sn 2+ and O cem were set to 0.7, 1.6, and 2.1 ∼ 2.2 eV, respectively, based on Aragoń et al 54) and Bendahmane et al 55) The O-Sn 2+ peak was observed to be stronger than the O-Sn 4+ peak for the sample with a deposition pressure of 0.3 Pa and f(O 2 ) value of 8%. Moreover, the O-Sn 4+ peak was observed to be stronger than the O-Sn 2+ peak for the sample with a deposition pressure of 0.3 Pa and f(O 2 ) value of 10%.…”

Enhancements of Structural and Optical Properties of MgO: SnO2 Nanostructure Films

“…The centrifugal force generated by the spinning causes the solution to spread uniformly across the substrate and evaporate, leaving behind a thin film on the surface [17] . MgO:SnO 2 thin films obtained by spin coating have potential applications in various fields, including optoelectronics [18], and gas sensors [19]. The properties of the thin films, such as their thickness, composition, and morphology, can be tuned by adjusting the concentration and ratio of the precursor materials in the solution and the spin-coating parameters, such as spin speed, spin time, and temperature [20].…”