Oscillatory diffusion in gold submonolayers over the Si(111)7 × 7 surface

Abstract A gold-deposited area of 0.1 mm diameter and several monolayers thick on the Si(111)7 × 7 surface is annealed at 700°C. In the diffusion process, the concentric oscillatory rings of the √3 × √3 and 5 × 1 structures are formed in an area of 0.4 mm diameter and observed by the dark field image in scanning LEED microscopy in an ultra-high vacuum. The diffusion is apparently independent of surface steps and crystallographic orientation from a macroscopic viewpoint. The formation of the periodic rings with the different surface structures and coverages is interpreted by using the surface diffusion equation and regarded as an intermediate phase prior to achieving the equilibrium state.