SCANNING-TUNNELING-MICROSCOPY STUDIES AND COMPUTER-SIMULATIONS OF ANNEALING OF GOLD-FILMS

The effect of thermal annealing on the surface morphology of thin gold films is studied using a scanning tunneling microscope (STM) and comp uter simulations. The gold films were thermally evaporated onto glass substrates, and were then measured with the STM at room temperature be fore and after annealing. The annealing treatments were done at temper atures between 200 and 500 degrees C and for periods ranging from 1 to 200 h. We present data showing the evolution of the average surface-g rain size and root-mean-square roughness amplitude of the gold films a s a function of annealing temperature and duration. Our data suggest t hat surface diffusion is the main process active at low annealing temp eratures of 300 degrees C and below. At higher annealing temperatures grain coarsening, which can be explained by recovery and recrystalliza tion (secondary grain growth), is the dominant process contributing to large scale morphology changes. Computer simulations based on these p rocesses account well for the experimental results, with activation en ergies of about 1.0 and 1.4 eV, for surface self-diffusion of gold and grain coarsening, respectively. (C) 1996 American Vacuum Society.