The spectral transmittance of Ta2O5 (tantalum oxide) films is 0.3 ~ 10um, which is one of the important high refractive index materials of visible light to near infrared band. Ta2O5 thin films with high refractive index and thermal stability, low absorption, amorphous microstructure and chemical corrosion resistance and other advantages, is widely applied in the preparation of a variety of optical components of the film, high anti film, beamsplitters and interference filter.
The amorphous film mainly has two important optical bandgap characteristics of the gap width and the Urbach band tail width. Among them, the forbidden band width characterizes the short wave absorption limit of thin film, and is also an important parameter to evaluate film absorption. The tail width is the key characteristic to evaluate the disorder degree of the inner structure. Therefore, the study of Ta2O5 film band gap is of great significance for its application in high damage threshold and low loss film.
Ta2O5 thin film preparation mainly include electron beam evaporation, evaporation of ion assisted, ion beam sputtering, magnetron sputtering, pulsed laser deposition, anodic oxidation, atomic layer deposition and sol-gel method. The optical properties of Ta2O5 films prepared by these preparation methods are different, and the preparation parameters have a great influence on Ta2O5 thin film characteristics under the same preparation technique. Since the 1970s, the preparation of Ta2O5 thin film by ion beam sputtering has become one of the main technologies in thin film field.
Ion beam sputtering Ta2O5 thin film research mainly concentrated in the ion beam, the baking temperature and optimizing the parameters of working gas flow ratio and the influence of heat treatment on the film performance, and won the ion beam sputtering preparation of Ta2O5 thin film refractive index, extinction coefficient and stress, the stoichiometric ratio, microstructure and optical band gap. In the adjustment method of optical band gap, the researchers adjusted the oxidation degree of Ta2O5 film to realize the regulation of film band gap. However, there are few studies on the regulation of Ta2O5 thin film band gap by ion beam sputtering.
