Au-induced faceting of the Si(5 5 12) surface

We have investigated Au-induced faceting of the high-index Si(5 5 12) surface for coverages up to ∼1 ML and temperatures between 600 and 800 °C using scanning tunneling microscopy. The surface predominantly forms sawtooth facets of the nearby (1 1 3) orientation, with an opposing facet plane that is determined by the Au coverage. These facet planes, which include (7 7 15), (3 3 7), (5 5 11), or (2 2 5), form one-domain, row-like surface structures with inter-row spacings that range from 2.2 to 3.5 nm. In contrast, the (1 1 3) plane forms either a clean 3 × 2 reconstruction with no long-range order or a disordered surface. Limited faceting to the low-index (1 1 1) plane is also observed at coverages above ∼0.2 ML.