Effects of Al incorporation on structural and humidity-sensing properties of SnO₂ sensor

In this study, we report on the humidity-sensing behavior of Al-doped SnO₂ materials to evaluate the effect of Al on enhanced sensing performance and propose a structural defects-dominating sensing mechanism of SnO₂. The diffractograms peaks are found to be broadened and shifted upon doping with the Al, reflecting the successful substitution of the Al. The variations of the UV band gap values regulate the concentration of electrons in the conduction band, which has significant implications for the electrical performance. The PL spectroscopy indicates the occurence of the lattice defects with the Al concentration increasing. Furthermore, Al-doped SnO₂ humidity sensor exhibits better hysteresis and response properties as the introduction of Al modifies inner structure of SnO₂. The possible chemical mechanisms for the enhancement on the humidity sensitivity induced by the surface defects in the prepared Al doping SnO₂ materials is also proposed.