Indium and tin oxide polycrystalline thin films as NO gas sensors produced by reactive pulsed laser ablation and deposition

Pulsed laser ablation is a very interesting method of depositing thin films of several materials and compounds, such as oxides, nitrides, insulators, semiconductors, and superconductors. Indium and tin oxide polycrystalline thin films have been grown on silicon (100) substrates by reactive PLD from two metallic targets of indium and tin by multilayered deposition, in the presence of oxygen, using a frequency-doubled Nd-YAG laser (lambda = 532 nm). The films produced have been studied to evaluate their use as NO gas sensors, and the best performance has been found by varying some important parameters, such as the substrate temperature and the pressure of oxygen in the deposition chamber. X-ray diffraction analysis of the deposited films shows that they are polycrystalline with a preferential (400) orientation. Electrical resistivity measurements, performed by using a four-point probe technique, show a sharp increase in resistivity when the films are exposed to NO. The electrical responses of tin oxide-indium oxide multilayered thin films are reported.