Annealing study of gold films using scanning tunneling microscopy

We have studied thermal annealing effects on the surface morphology of 800 A thick gold films, using scanning tunneling microscopy. The gold films were thermally evaporated onto glass substrates and were then measured with the scanning tunneling microscope at room temperature before and after annealing. The annealing treatments were done at temperatures between 200 and 500 °C and for periods ranging from 1 to 60 h. We present data showing the evolution of the average surface-grain size and rms roughness amplitude of the gold films as a function of annealing temperature and duration. Our data suggest that surface diffusion is the main process active at low annealing temperatures of 300 °C and below. The activation energy for surface self-diffusion of gold in our samples was around 1.1 eV. Other mechanisms seem to be dominant at higher temperatures.