Dynamic phenomena in the surface of gold thin films: Macroscopic surface rearrangements

The temporal evolution of the surface topography and X-ray spectrum of gold thin films is obtained. We found by scanning tunneling microscopy that the surface roughness decreases exponentially with time. As the X-ray incidence angle decreases the peak positions shift and the peak half-widths increase. These results indicate that microcrystals in the surface are under strain and are smaller than in the bulk. The X-ray peak positions shift with elapsed time towards the gold standards. The conclusion of the study is that rearrangement of the gold film surface is induced by surface strains that appear during film growth. Thus, the surface smoothing is due to relaxation of the stress in the material rather than to the thermal motion of atoms.