Effects of different oxygen flow on refractive index and absorption characteristics of Ta2O5 film

Ta2O5 film has low absorption in the range of visible wavelength and it has high refractive index and thermal stability. So it is widely used to prepare low loss films. Ta2O5 single layer with different oxygen flow rates were prepared by ion beam sputtering technique. The refractive index and absorption characteristics of metal oxide films were compared at different oxygen flow rates. The refractive index and absorption of thin film materials were studied by ellipsometry technology and surface thermal lens technology. The results show that: the absorption of Ta2O5 film is decreased first and then increased with the increase of oxygen flow. When oxygen flow is 40 sccm, the absorption is smallest, only 4.4ppm. And the refractive index is decreased with oxygen flow increasing, after oxygen flow reached 40 sccm, the refractive index tend to be stable.