Self-Smoothening of an Ion-Beam-Sputtered Ag (100) Surface: Evolution of Surface Morphology Using RHEED

The development of the surface morphology and rough-to-smooth transition of the ion beam-sputtered Ag (100) surface was studied using reflection high-energy electron diffraction (RHEED) at two different temperatures. After sputtering, self-evolution of the Ag (100) surface morphology was continuously monitored by the passage from spotty to streaky RHEED patterns. This approach allowed us to follow the qualitative time evolution of the surface morphology of the Ag (100) surface, which underwent a self-transition from a rough-to-smooth surface (3D rough surface to 2D-like smooth surface) within 120 minutes at room temperature (RT) and about 60 minutes at 323 K temperature. Once the saturation in smoothness was reached, no significant changes in surface morphology with time were observed. At temperatures about 323 K, the achieved smoothness value was about 12 pct more than that observed at RT. The surface smoothing process at RT is understood in terms of self-diffusion, nucleation of randomly distributed defects and vacancies, whereas increased surface diffusion due to an increase in temperature leads to a smoother surface.