Study on water absorption characteristics of cubic Y2O3 films

Based on the electron beam evaporation with oxygen plasma assistance, Y2O3 films were prepared at different deposition temperatures and oxygen flow rates. X-ray diffraction showed that all deposited Y2O3 films had cubic phase with (2 2 2) plane preferred orientation. Spectrometer test results showed that water absorption decreases in transmittance and reflectance around the wavelength of 2.9 mu m. According to Lorentz dispersion theory, a multi-oscillator model was established to calculate optical constants and the inhomogeneity of Y2O3 films in the wavelength range from 2.5 to 4 mu m. The results indicate an abnormal dispersion phenomenon is appearing in the 2.5-4 mu m wavelength region. It was found that under the same oxygen flow rate, higher substrate temperature leads to a greater refractive index and smaller extinction coefficient. When the oxygen flow rate is increased at the same substrate temperature, the extinction coefficient remains almost unchanged, while the refractive index decreases. In addition, the refractive index and the inhomogeneity of the films increase almost linearly as the grain size increases.