Hierarchical nanostructured semiconductor porous materials for gas sensors

Gas sensitive layers with a fractal structure based on tin oxide were prepared by the sol–gel-method. Investigations of the film structure were carried out by atomic force microscopy. The basic evolution steps of this fractal system were found to be diffusion-limited aggregation, cluster–cluster aggregation, formation of percolating transition and netting nanostructures. Gas-sensitivity measurements of synthesized samples were taken. The emergence of a new relaxation in the presence of reducing gases was found in the Cole–Cole plots. Sensor nanostructures were investigated by impedance spectroscopy in different gas environments and gas reagent detection temperatures. AC measurements made it possible to develop selective gas sensors and multisensor systems.