Structural and electronic properties of thallium overlayers on the Si(111)-7 × 7 surface

S. S. Lee, H. J. Song, N. D. Kim, J. W. Chung, K. Kong, D. Ahn, H. Yi, B. D. Yu, Hiroshi Tochihara

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63 Scopus citations


We have investigated atomic arrangements and their electronic properties of the well-ordered thallium overlayer structures formed on the Si(111)-7 × 7 surface. As for other trivalent atoms, T1 is found to form a well-defined √3 × √3 surface, indicating the absence of a so-called "inert pair effect" considered only for T1. Another well ordered 1 × 1 surface at 1.0 monolayer appears to be semiconducting in our angle-resolved photoemission spectra dominated by a unique dispersive surface band near the Fermi level. Our theoretical calculations using density-functional theory show that T1 adatoms occupy the T4 sites and saturate all the dangling bonds of surface Si atoms to make the surface semiconducting with a band gap of 0.34 eV. The filled surface band observed has been well reproduced in our band calculations.

Original languageEnglish
Article number233312
Pages (from-to)2333121-2333124
Number of pages4
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number23
StatePublished - 15 Dec 2002


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