Structural and optical properties of yttrium trioxide thin films prepared by RF magnetron sputtering

Yttrium trioxide (Y2O3) thin films have been deposited on silicon (111) at different RF powers and the sputtering pressures by RF magnetron sputtering. The influences of the RF power and the sputtering pressures on the structural and optical properties of Y2O3 thin films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM) and spectroscopic ellipsometer (SE). The results show that chemical composition of as-deposited Y2O3 film is apparently close to the stoichiometric ratio and it is crystallized but crystallinity is poor. The monoclinic and cubic fluorite-like structure can coexist in as-deposited Y2O3 film. A four-layer-structured optical model consisting of silicon substrate, silicon dioxide (SiO2) interlayer, Y2O3 layer and a surface roughness (SR) layer is built for interpreting preferably the results measured by spectroscopic ellipsometry. With the increase of RF power or decrease of sputtering pressure, the refractive index and optical bandgap of sputtered Y2O3 film is increased and the extinction coefficients is decreased.

► The influences of the RF power and the sputtering pressures on the structural and optical properties of Y2O3 thin films deposited by RF magnetron sputtering investigated by XPS, XRD, AFM, and SE.
► Sputtered Y2O3 film exhibits a monoclinic structure even at rather low RF power, but it will be transformed into cubic fluorite-like structure at high RF power.
► A four-layer-structured optical model consisting of substrate is built for interpreting preferably the results measured by SE.
► It can be seen that the refractive index and optical bandgap of sputtered Y2O3 film are increased and the extinction coefficients is decreased with the increase of RF power or decrease of sputtering pressure.
► It is directly related with the increase in the film's compactness as the deposition rate increases.