Y2O3 thin films were deposited by ion beam assisted deposition (IBAD) and the effects of fabrication parameters such as substrate temperature and ion energy on the structure, optical and electrical properties of the films were investigated. The results show that the deposited Y2O3 films had less optical absorption, larger refractive index, and better film crystallinity with the increase of substrate temperature or ion energy. The as-deposited Y2O3 films without ion-beam bombardment had larger relative dielectric constant (epsilon(r)) and the epsilon(r) decreased with time even over by 40%, while the epsilon(r) of films prepared with high ion energy had less changes, only less than 3%. Also, with the increase of ion energy, the electrical breakdown strength and the figure of merit increased. (C) 2010 Elsevier B. V. All rights reserved.