A method for forming a silicon oxide film, SiO.sub.x, where X=1 or 2, on an electrode of a thin film transistor, e.g., for a liquid crystal display device. The method includes the steps of: forming an electrode on a substrate; forming an organic silicon-containing thin film on exposed surfaces of the electrode and the substrate; providing a gaseous atmosphere of oxygen or air about the electrode and the substrate; and irradiating the thin film with ultra violet light to produce radicals, including silicon radicals, from the thin film. The irradiation also produces oxygen radicals from the atmosphere. The silicon and oxygen radicals react to form the silicon oxide.