We study the structure of epitaxial Gd2O3 layers grown on Si(0 0 1) using reflection high-energy electron diffraction (RHEED) and grazing incidence X-ray diffraction (GIXRD). When the oxygen partial pressure is not sufficiently high, GIXRD reveals a silicide phase at the interface. The use of higher oxygen pressure results in a rapid decrease in the crystallinity of the Gd2O3 layers and they become amorphous. Increasing the Substrate temperature from 650 to 700 degrees C improves the epitaxy with larger domains and smoother surfaces. Also no silicide phase is detected by GIXRD. Therefore, the control of oxygen pressure and substrate temperature is very important to obtain high-quality epitaxial Gd2O3 layers without silicide at the interface. (c) 2008 Elsevier B.V. All rights reserved.