Observations of Gold Atomic Clusters in Magnesium Oxide Films under Off-Bragg Conditions

By a simultaneous vacuum-deposition technique, gold is embedded epltaxlally as small crystallites less than a few nm in size and a few atomic layers in thickness in (001) and (Oil) single crystalline magnesium oxide (MgO) films. In order to observe small gold clusters in the MgO films, elec-tron microscope observations with tilted electron Incidence are performed In addition to axial electron incidence. Lattice fringes of MgO which disturb identification of the small clusters are eliminated in the off-Bragg conditions by using nearly [113] Incidence for the (001) films, and by a rotation of films by 10 ° around the [110] axis for the (011) films. In the micrographs taken in the conditions, images of gold clusters of monolayer and of a few atoms or less are observed with sufficient image contrast. Key wor<£r = ofT-Bragg high resolution electron microscopy (HREM): gold-magnesitun oxide (Au-MgO): composite film: atomic cluster: simultaneous vacuum-depositio