The coverage-dependent valence state of Tl adsorbed on a Si (111) - (7×7) surface and the coverage dependence of the charge states of surface Si atoms have been investigated by high-resolution core-level photoelectron spectroscopy. Although two different reconstructions were observed in low-energy electron diffraction at different coverages, a (1×1) pattern at a Tl coverage of 1 monolayer (ML) and a (3×3) pattern at a coverage of 13 ML, the binding energy of the Tl 5d core-level was the same at Tl coverages up to 1 ML. Taking the valence state on a (1×1) surface reported in the literature into account, we conclude that the valence state of Tl is 1+, and that the 6 s2 electrons of Tl are inactive as an inert pair in the Tl-Si bonding on a Si(111) surface at a coverage of 1 ML and below. In the Si 2p core-level spectra, one surface component was observed on the (1×1) surface, and three surface components were observed on the (3×3) surface. The binding energies and intensities of the Si 2p surface components indicate that the charge state of the surface Si atoms on Tl Si (111) - (1×1) is the same as that of the (3×3) surfaces induced by the other group III metals, but they are different on the Tl Si (111) - (3×3) surface.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Sep 7 2006|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics