Structural and electrical properties of In2O3/SeO2 thin films for gas-sensing applications

In this work, we report about the analysis of structural, physical, and gas -sensing properties of a new sensing material made by mixing In2O3 and SeO2 . The In2O3/SeO2 thin films have been obtained by thermal evaporation of In :Se in a 2:1 ratio and subsequent thermal annealing in an oxygen flow. In o rder to investigate the structure and the morphology of the films obtained, high-resolution transmission electron microscopy, small-area electron diff raction, and digital image processing were performed on thermally annealed films. The Hall effect and resistivity measurements of such films have been carefully analysed. In addition, In2O3/SeO2 mixed oxide films were tested in a controlled atmosphere and the electrical conductance changes were meas ured as a function of temperature. The sensing behaviour of such films has been analysed according to an adsor ption kinetic model, which related the conductivity variation to gas concen trations, time exposure, and working temperature.