Study Of The Preparation Of TiO₂ Thin Film By Reactive E-beam Evaporation From Ti₂O₃

TiO₂ is often used as high refractive index material in optical thin film preparation. When preparing TiO₂ thin film by E-beam evaporation, the properties of thin film depend on the process parameter, and thin films prepared by E-beam evaporation and sputtering is amorphous. In these methods, process parameters affect the properties of thin film seriously.The titanium-oxygen is well known for the complexity of its various oxidation states, and many solid phases are identified, such as TiO₂, TiO, Ti₂O₃, Ti₃O₅, Ti₄O₇, TiO₂, etc. In the gas phase, Ti, TiO, TiO₂, O₂ and O are found. Among these solid phases, TiO, Ti₂O₃, Ti₃O₅ and TiO₂ are often used to prepare optical TiO₂ thin film in an oxygen environment. Own to the decomposition of titanium oxides in evaporating process, the transmission of thin film is very bad in the visual region. So it's necessary with ion auxiliary to prepare the TiO₂ thin film by E-beam evaporation from Ti sub-oxides.After adding IAD with O₂ (purity 99.99%) as ion source, we prepared the TiO₂ thin films by the ZZS700-6/G vacuum electron-beam deposition system. The microstructure and optical characteristics of thin films were investigated at various process parameters, such as different parameters of ion source, oxygen flux and anneal treatment. We studied the structures of origin material and residual material by XRD. And we analyzed the effect of evaporation process on film forming and film's properties.We measured the transmittances spectra through UV 755B Spectrophotometer, and deduced refractive indexes from the extremum of reflectance or transmittance. The experiments results show that the thin films taken Ti₂O₃ as origin material have strong absorption;ion assistant is benefit to gain high oxidation compounds. However, taken TiO₂ as origin material, the thin film has good transmittance, and the refractive index changed from 2.23 to 2.73 in visible light region. The experiments show that the Ti₃O₅ is the congruent evaporation phase in the Ti-0 system, and various evaporation substances eventually vaporize as Ti₃O₅. And anneal treatment is propitious to forming steady crystal structure, thus enhance the transmittance and stability of thin film.