The structure of gold films grown in ultra-high vacuum on sodium chloride substrates

Abstract

Abstract Sodium chloride crystals were cleaved in ultra-high vacuum while the evaporation of gold was in progress. The films that grew on the freshly exposed (001) surfaces were examined in a transmission electron microscope, and in a reflection electron diffraction camera. A film grown at a deposition rate of about 2000 Å. per second on sodium chloride at 360°C was a single crystal in the orientation of the substrate. Films grown more slowly on sodium chloride at 20, 150, 250, 320, 360, 420 and 460°C were polycrystals with nine preferrred orientations. One of these was parallel to the substrate lattice. Four had (111) parallel to the deposit plane, and a <110> direction parallel to one of the two <110> directions in the salt surface. The remaining four had (111) parallel to the deposit plane, and <110> parallel to a <100> direction in the surface of the salt. The relative concentration of the preferred orientations varied greatly with deposit thickness. Later experiments showed that single-crystal foils in the orientation of the substrate were obtained at low deposition rates, if the substrate was exposed to air prior to the desposition of gold upon it.