Modification of Gas Sensitivity in ZnSnO3 Film from Carrier Behaviors: Derivation, Concentration, and Depletion

An attempt was made to explore the relationship between the gas sensing performance of ZnSnO3 thin films and their intrinsic charge carrier behaviors. ZnSnO3 films with miscellaneous electrical characteristics were obtained by the combination of like-chemical oxygen control, fluorine doping, and like-physical light conditioning. The microstructure, morphology, optical transparency, electrical characteristics, and gas sensing performance were analyzed by X-ray diffraction, Raman spectroscopy, atomic force microscopy, ultraviolet spectrophotometer, Hall effect apparatus, and electrochemical testing system, respectively. The results show that through F–O coregulation, the carrier concentration of ZnSnO3 thin films was increased from 1017 to 1018 cm–3, the sensitivity was increased from 0.09 to 0.26, the response/recovery time was reduced from 165 s/153 s to 129 s/110 s, and the optimal operating temperature was lowered to 280 °C. The irradiation of simulating solar intentionally enhanced the carrier concentration, which significantly increased the sensitivity to 31.16 and greatly reduced the response/recovery time to 79 s/68 s. The minimum limit of detection concentration has been reduced to 2 ppm for dense and simple film, and even the minimum operating temperature has been drastically lowered to room temperature. For various derivated carriers with different concentrations, the mechanism of depletion and accumulation on the gas-sensitive response is proposed.