Scanning tunnelling microscopy was used to determine the surface structure of the √3 x √3 reconstruction induced by Bi on the Si(111) surface. The scanning tunnelling microscopic images show that there were two distinct ordered surfaces with √3 x √3 periodicity. At 1/3-monolayer Bi coverage, the √3 x √3 phase consisted of one Bi adatom per unit cell adsorbed at T4 sites on a Si(111) bilayer. At nearly one monolayer of Bi coverage, scanning tunnelling microscopic images show protrusions with a complex shape dependent on bias voltage. These scanning tunnelling microscopic images were discussed and compared with structural models derived from previous experimental studies.

Bi on Si(111) - Two Phases of the √3 x √3 Surface Reconstruction. R.Shioda, A.Kawazu, A.A.Baski, C.F.Quate, J.Nogami: Physical Review B, 1993, 48, 4895-8