STRUCTURAL, ELECTRICAL AND INTERFACIAL PROPERTIES OF SPRAYED SNO2 FILMS

The resistivity of SnO2 films fabricated by spray pyrolysis of SnCl4 m ethanolic solutions can vary over nearly six orders of magnitude depen ding on the conditions of preparation [substrate temperature, concentr ation of SnCl4 and nature of the dopant (Cl, F, Sb)]. At low carrier d ensity, the resistivity is determined by charge trapping at grain boun daries. In the case of highly degenerated materials, grain boundaries do not play a role anymore. The film resistivity is fully controlled b y the bulk grain electrical properties, which are found to be dependen t on the defect structure generated by the dopant. Thanks to Transmiss ion Electron Microscopy, it is shown that chlorine or fluorine incorpo ration promotes the formation of the same neutral defects, which are { 011} cassiterite twins. On the other hand, antimony gives rise to spec ific charged structural defects which strongly lower the carrier mobil ity. The electrical transport properties of F-doped SnO2 films are bet ter than those of Sb-doped materials. Considering the interfacial elec tron transfer with a redox system. Sb-doped electrodes are the most ef ficient because they achieve the highest carrier density, with perform ances approaching those of massive metal electrodes.