Electronic structures of Ga-induced incommensurate and commensurate overlayers on the Si(111) surface
SCIE
SCOPUS
- Title
- Electronic structures of Ga-induced incommensurate and commensurate overlayers on the Si(111) surface
- Authors
- Yeom, HW; Yoo, K; Oh, DH
- Date Issued
- 2011-01
- Publisher
- ELSEVIER
- Abstract
- Electronic band structures of Ga-induced dense overlayers on the Si(111) surface have been investigated using angle-resolved photoelectron spectroscopy and first-principle density-functional theory calculations. The well-known incommensurate 6.3 x 6.3 phase formed by the growth on the Si(111)7x7 surface and the newly found 1 x 1 phase grown on the preformed Si(111)root 3 x root 3-Ga surface are characterized in detail. A highly dispersive surface state (S) is observed for the incommensurate phase but only a weakly dispersing one (S') for the 1 x 1 surface. Both surfaces are found to be nonmetallic, with their surface states fully occupied. The theoretical calculation reproduces well the S band of the 6.3 x 6.3 phase on the basis of a simple 1 x 1 Ga-Si bilayer structure formed with substitutional Ga atoms, which was proposed previously. No explicit sign of the incommensurate periodicity is found in the measured band dispersions, indicating a very weak incommensurate potential. The S band is shown to originate in the sp(2)-like planar bonds within the Ga-Si bilayer. The width of the S band is sensitive to the surface strain in the calculation and about 8% expansion of the Ga-Si bilayer lattice was needed to reproduce the measured dispersions, which is in good agreement with the previous X-ray study. On the other hand, the surface state S of the commensurate 1 x 1 phase cannot be explained by any simple model of a substitutional or adsorbed Ga layer. Further structural studies are thus requested. The second Ga layer, which is metallic, grows two-dimensionally over this 1 x 1 layer up to a total coverage of about 5 ML. (C) 2010 Elsevier B.V. All rights reserved.
- Keywords
- Gallium; Silicon; Angle-resolved photoemission; Surface electronic phenomena; Metal-Semiconductor interface; RESOLVED PHOTOELECTRON-SPECTROSCOPY; TOTAL-ENERGY CALCULATIONS; WAVE BASIS-SET; SILICON SURFACE; RECONSTRUCTIONS; MONOLAYER; GALLIUM; SYSTEM; STATES
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/14888
- DOI
- 10.1016/J.SUSC.2010.10.012
- ISSN
- 0039-6028
- Article Type
- Article
- Citation
- SURFACE SCIENCE, vol. 605, no. 1-2, page. 146 - 152, 2011-01
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