The Preparation And Study Of Indium Tin Oxide (ITO) Thin Films

Since 1990s, the rapid development of projector display and optical communications promotes the progress of photoelectric thin films, and more technology requests appear in the photoelectric coating field. In response to the demands of transparent electrode of solar cell, photoelectric thin films are prepared and discussed.Due to big carrier concentration and optical band gap, transparent conductive oxide thin films exhibit outstanding optical and electrical properties, such as low resistivity and high transmittance in the visible range etc.At present, this kind of material system include In2O3,SnO2,ZnO and dopant system In2O3:Sn(lTO),SnO2:Sb,SnO2:F,ZnO:Al(ZAO) etc. Among them, SnO2 (TO) and In2O3:SnO2 (ITO) films have been widely used in liquid crystal display and solar cell as transparent electrode.Many processes are used to prepare transparent conductive films, such as magnetron sputtering, vacuum reactive evaporation, chemical vapor depositions, Sol-gel, laser-pulsed deposition. Among these methods, magnetron sputtering is the most widely used technique for preparing thin films, owing to its high deposition rate and good uniformity etc.ITO films were prepared by RF and DC magnetron sputtering in pure argon gas atmosphere, using In2O3 and In target mixed with SnO2 (10wt %) and Sn (7wt %) respectively. The films were figured by XRD, SEM and Visible Light, UV photometer. It was concluded that, the structure of ITO thin films were influenced by many working parameters such as substrate temperature, oxygenous pressure and substrate and so on. It was indicated by SEM spectra of ZnO thin films that the surface of the sample was leveled off, and the crystals were felsitic. It was found from the experiment that, with the increasing of substrate temperature, there were more oxygen vacancies in the films, which lead the conductance of the sample become larger, and the absorb edge of ITO thin films shifted toward lower wavelength; with increasing of Ar: O2 ratio, there were lesser oxygen vacancies in the films, which lead the absorb edge of ITO thin films shifted toward lower wavelength.