Epitaxial growth of gamma-Al2O3 films was carried out by molecular beam epitaxy (MBE) in either O-2 or N2O ambient and with substrate temperature and pressure ranging from 600 to 800 degrees C and 5 x 10(-4) to 3 x 10(-2) Pa, respectively. Using N2O gas, pits caused by the etching of Si were observed at a gas pressure of 3 x 10(-2) Pa and substrate temperature of 800 degrees C, and Al droplets were formed at 5 x 10(-4) Pa and 800 degrees C, while neither pits nor droplets were obtained with O-2 under the same growth conditions. This suggests that O-2 is a more suitable oxidation gas than N2O for growing epitaxial gamma-Al2O3 films. (C) 2007 Elsevier B.V. All rights reserved.