The simple metal indium is known to induce different reconstructions of the silicon (111) surface in the range of metal coverages below one monolayer (1 ML). We have studied both the $\sqrt{3}\times \sqrt{3}$ and the 4×1 reconstructions with scanning tunneling microscopy. Images of the $\sqrt{3}\times \sqrt{3}$ surface are consistent with $\frac{1}{3}$ ML of In adatoms resting in threefold sites. The higher-coverage 4×1 surface consists of large reconstructed terraces often bounded by abrupt, stepped edges. Growth of flat metal islands is also seen around 1 ML.

• Received 20 July 1987

DOI:https://doi.org/10.1103/PhysRevB.36.6221