Preferred orientations in nano-gold/silica/silicon interfaces

Gold in contact with silicon substrates Si(1 0 0), Si(1 1 1), and SiO₂ is studied by thermal evaporation and annealing in N₂ using the modified sphere-plate technique. The final orientation distribution of crystalline Au films grown on Si substrate systems that incorporate a native amorphous oxide layer of silica and Au on amorphous silica (SiO₂ glass) substrates is influenced by preferred orientations and twinning. Experimental evidence suggests that the orientation of Au{1 1 1} close packed planes (multiply twinned) was found to be of low-energy as the annealing temperature was increased to 530 °C and 920 °C. Additional orientations were observed for Au{1 0 0} on Si(1 0 0) substrates and Au{1 0 0}, {1 1 0}, and {3 1 1} on SiO₂ substrates. After annealing at 920 °C the size distribution of the gold particles was determined to be within the range of 20-800 nm while the morphology of gold surface appears spherical to faceted in character. These results show similarities to recent findings for smaller nano-size 1D particles, islands and thin Au films on silicon annealed over lower temperature ranges.