On The Sol-Gel Processing And Mechanism For Antimony-Doped Tin Oxide Conducting Thin Film

Ever since the invention of transparent conducting CdO films prepared by the thermal oxidation of sputtered cadmium by Bakdeker in 1907, the technological interest in transparent conductors had grown tremendously. In the recent years, the films had found major applications in many fields. It is not only the interest of research but also the requirement of the market to seek efficient films especially the theory of films' formation and conduction by a specified processing for new material. This paper presents a comprehensive introduction of metal oxides thin film, especially research and application of antimony-doped tin oxide (ATO) conductors. On the basis of research and the requirement of application in the field of industry, it is determined to prepare ATO films using metal salts SnCl2?H2O and SbCl3 as initializing materials and deploying Sol-Gel processing. By XRD and SEM respectively, the heat-treatment temperature, film thickness and doping level, having strong influence on the microstructure and composition of ATO conducting film, has been found. The basis of theory and the experiment process for deposition of such films at room temperature by Sol-Gel technique on the glass are interpreted. The detailed values for ATO conducting films are given. The sheet resistance of the film, which is doped by antimony at 10mol%, dipped four times and annealed from 500℃, decreases to 130?/□ or so. What's more, the theory of the films shaping and conducting is discussed. There are some key reactions such as alcoholysis reaction in the processing of Sol preparation, dehydration reaction and condensation polymerization when films are coated and consolidation in the process of desiccation and sinter. It is indicating from the research for ATO film that antimony doped can improve the appearance,that is to say, the sheet resistance of the film becomes lower than the pure SnO2 film. When the content of antimony in the doped film is overlarge, conducting property becomes badly due to the ion scattering of antimony. There are two reasons for ATO film's conducting, one is oxygen vacancy in the crystal lattice and another is Sb5+ impurity which forms donor level in the forbidden band of SnO2 and offers n-type carriers to conduction band. With the increment of antimony impurity in ATO conducting films, oxidation state of antimony have a competition between Sb3+ and Sb5+. On the basis of the crystal model of SnO2, the electrical conductivity in theory is calculated, consistent with the conducting mechanism of the ATO thin film which was discussed. It has reference significance for perfecting the Sol-Gel processing of ATO conducting thin films.