The structure of silicon surfaces from (001) to (111)

• Published in: Surface science Vol. 392; no. 1; pp. 69 - 85
• Main Authors: Baski, A.A., Erwin, S.C., Whitman, L.J.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-12-1997; Amsterdam Elsevier Science; New York, NY
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; High-index surfaces; Morphology; Physics; Reconstruction; Scanning tunneling microscopy; Silicon; Solid surfaces and solid-solid interfaces; Surface structure; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); High-index surfaces; Reconstruction; Scanning tunneling microscopy; Silicon; Morphology; Surface structure; Surface reconstruction; Terrace; Theoretical study; Step; Intermediate structure; Experimental study; Faceting
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(97)00499-8

We describe the structure of silicon surfaces oriented between (001) and (111) as determined by scanning tunneling microscopy (STM) and first-principles, total-energy calculations. In addition to reviewing and reproducing the structures reported for the few surfaces previously studied, we describe a number of additional surfaces in order to provide a complete overview of the (001)-to-(111) surface morphology. As the sample orientation is titled from (001) to (111) (ϑ=0 to 54.7°), the surface morphology varies as follows: (1) Si(001) to Si(114) = (001)-like surfaces composed of dimers separated by steps (both rebonded and nonrebonded); (2) Si(114) to Si(113) =mesoscale sawtooth facets composed of the stable (114)−2 × 1 and (113)−3 × 2 planes; (3) Si(113) to Si(5 5 12) =mesofacets composed of (113)−3 × 2 and (5 5 12)-like planes; (4) Si(5 5 12) to ∼Si(223) =nanoscale sawtooth facets composed of (5 5 12)-like and unit-cell-wide (111)−7 × 7 planes; and (5) ∼Si(223) to Si(111)=(111)−7 × 7 terraces separated primarily by single- and triple-layer steps. The change in the surface morphology is accompanied by a change in the composition of surface structural units, progressing from (001)-like structures (e.g. dimers, rebonded steps, and tetramers) to (111)-like structures (π-bonded chains, adatoms and dimer-chain walls). The resultant morphology is a delicate balance between the reduction of dangling bond density achieved by the formation of these structural units, and the resulting surface stress associated with their unusual bond angles and bond lengths.