Abstract
We report an fcc structure for the epitaxial Gd 2 O 3 films grown on GaAs(100). This fluorite-derived structure appears to be stabilized by epitaxy with the substrate and has a great similarity to the GaAs structure. A model calculation supports this finding. Our secondary-electron imaging studies of these nanometer-thick films reveal that the films are cubic as deposited, and this structure can be derived from the stable α-phase of the Gd 2 O 3 by a mild Ne + -ion bombardment and a subsequent anneal. These epitaxial Gd 2 O 3 films have great importance because of their excellent surface passivation properties.