Parameters affecting the electrical conductivity of SnO2:Sb sol-gel coatings

SnO2: Sb single and multilayer coatings have been prepared by the sol-gel dip and spin coating method, and by spray pyrolysis from various precursor solutions. Subsequently, the films have been heat treated in a convection furnace or by cw CO2 laser irradiation, respectively. The influence of the different deposition and heating techniques on the electrical and morphological properties of the resulting films has been investigated by van der Pauw/Hall method and high resolution transmission electron microscopy (HRTEM) cross-sectional images. It is shown that the resistivities of the dip and spin coated films are at least one order of magnitude higher compared to those of spray coated films obtained from the same precursor solution. In dip coated multilayer systems an alternating structure of loosely packed and dense layers can be observed leading to a decrease in resistivity with the number of layers. A similar densified surface structure is found in laser treated films together with larger crystallites. It is concluded that the differences in resistivity occurring from the deposition technique and the heating process are linked to structural differences of the coatings whereas the chemical composition of the solution plays a minor role for the electrical properties