The role of stoichiometry of indium and oxygen on gas sensing properties of indium oxide nanostructures

We report direct evidence of the role of stoichiometry of one-dimensional indium oxide (IO) nanostructures grown by vapor-phase evaporation method on the ethanol gas sensing properties. The stoichiometric crystalline In2O3 nanowires grown under oxidizing (water) ambient exhibit about two orders of magnitude higher sensor response value of 281 in comparison to nonstoichiometric (In/O ∼0.75) nanotubes grown under reducing (ethanol) ambient in presence of 1000 ppm ethanol gas at 300 °C. We propose that for a stoichiometric IO nanowire, Debye region completely depletes the nanowire from free charge carriers which results in a significant increase in the sensor response.