Unique surface structure formations on a Ge-covered Si(110)-16×2 surface

•Si–Ge structures forming new shapes on a Si(110) surface were investigated via STM.•A new double-domain Si–Ge striped structure was formed at low Ge coverage.•Pyramidal-shaped Si–Ge nanoislands were formed at high Ge coverage.•The surface structure changes specifically with trace amounts of Ge.

Si–Ge structures forming new shapes on a Si(110)-16×2 reconstructed surface were investigated via scanning tunneling microscopy. Pyramidal-shaped Si–Ge nanoislands lying along the <1 1 1> directions were formed on the striped structure at Ge coverage between 3 and 6 monolayers. However, when a single monolayer of Ge was deposited on the Si(110)-16×2 surface, single-domain of 16×2 striped structure disappeared, and a new double-domain striped structure was formed over the surface along directions that differed from the <1 1 2> directions. This structure represents a new Si–Ge striped structure that forms by the mixing of Ge and Si due to high temperature annealing. These results indicate that the surface structure changes specifically with trace amounts of Ge.