Evolution of composition, microstructure and optical properties of yttrium oxide thin films with substrate temperature

Abstract

A series of yttrium oxide films has been fabricated on Si (100) wafers by different substrate temperatures based on reactive magnetron sputtering technology. And the evolution of composition, microstructure and optical properties of Y2O3 films has been investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and spectroscopic ellipsometry (SE). It is shown that stoichiometric Y2O3 with much strong YO bond and cubic nanophase with larger size notably enhance the optical properties, especially refractive index. At low substrate temperature, the composition of Y2O3 films has nonstoichiometry feature accompanying with much physisorbed oxygen (Oδ) compared with these at high temperature. Increasing substrate temperature promotes the formation of YO bonds, approaching the stoichiometry with lower Oδ content. The film commences crystallizing at room temperature, and transformation of crystalline phase from monoclinic to cubic occurs, along with preferred (111) orientation and large grain as temperature increases. The results facilitate clear relationship between the characterizations of Y2O3 film and growth parameters, also, it can be realized that adjustment of optical constants of Y2O3 films in a large range having the aid of substrate temperature to obtain desirable composition and structure for optical applications.