Nanostructured In2O3–SnO2 sol–gel thin film as material for NO2 detection

Nanocrystalline SnO2, In2O3 and In2O3–SnO2 thin films have been prepared by modified sol–gel methods making use of no-standard precursors and a suitable surfactant. The oxide thin films have been used as gas-sensing layers in chemoresistive gas sensors and their performances in the detection of nitrogen dioxide (2–20 ppm in dry air) have been analysed by electrical characterization in controlled atmosphere. The samples have been structurally and morphologically characterized by X-ray diffraction and SEM, respectively. Good gas-sensing responses towards NO2 have been found for all the prepared samples with improved performances for the In2O3–SnO2 based sensor. The performances of the sensors have been discussed according to the surface chemical reactions between the gas phase and the semiconductor.