[2D05-11] Surface Science (SS1) Physical Property

10:15 AM - 10:45 AM JST(1:15 AM - 1:45 AM UTC)

[2D05【論文賞】] Simple model for striped-incommensurate phase formed by Pb adsorption on Si(111)

*Masamichi Yamada¹, Yudai Sato¹, Masahiro Haze¹, Yukio Hasegawa¹ (1. The Institute for Solid State Physics, The University of Tokyo (Japan))

Lead (Pb) deposition on Si(111) forms the striped-incommensurate (SIC) phase around the completion of the first Pb layer. The Pb coverage is about 1.28 relative to Si(111) surface, i.e., slightly less than the coverage, 1.33, of the ideal (√3×√3)-Pb structure. The SIC structure is difficult to analyze in detail due to its incommensurate nature. Even an approximate model requires a large unit cell. In this presentation, we present a simple model based on hard-sphere approach, and show that the driving force which leads to the SIC phase is compressive stress inherent to the ideal √3×√3 structure. The stress is relieved by uniaxial [-110] expansion of the adsorbed Pb layer. Subsequent twin-like, slight deformation enables Pb atoms to occupy stable H3 and T4 sites as many as possible. The resultant model well accounts for various features observed by scanning tunneling microscopy on the SIC phase, especially chevron-like alignment of protrusions.

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