In this study, un-doped and doped yttrium oxide (Y2O3) powders with different erbium concentrations were synthesized using sol-gel method. The synthesized powders were investigated by Raman analysis and the evolution of different peaks associated with Er dopant in Y2O3 structure was clearly observed. Moreover, the powders were deposited on Corning glasses using electron beam (e-beam) evaporation method. The samples were heat-treated at 300 and 400 degrees C temperatures for 6 h. The effects of the heat treatment temperatures and dopant concentrations on the optical properties were investigated. Phase constituents of the thin films were analyzed by X-ray diffraction with a thin film attachment using Cu-K-alpha radiation. Optical transmittance curves of the films were measured using optical spectrophotometer. Cross sectional morphologies of the films were examined using scanning electron microscopy (SEM). It was observed that Er dopants caused a shift in the transmittance curves to UV region.