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

► Increasing substrate temperature promotes the formation of YO bond. ► The stoichiometry increases and approaches theoretical stoichiometry at 400 °C. ► Structural transformation occurs with grain growth as temperature increases. ► Strong YO bond and good crystallinity enhance the refractive index of Y2O3 films. ► The relation of grown parameter-structure-optical properties is well established.