2004 Volume 2 Pages 210-221
In this review, we present a series of photoemission studies performed on the so-called metal induced Si(111)-(3×1) surface, which is one of the most well known 1D structure formed on a Si(111) surface. Three different kinds of metals have been used as adsorbate, K, Ca, and Ag.On the K/Si(111)-(3×1) surface, five surface components were observed in the Si 2p core-level spectra. The energy shift and intensity of each surface component indicates that this surface has the honeycomb-chain-channel (HCC) structure with a K coverage of 1⁄3 ML. The extra spots observed in the LEED pattern of the so-called Ca/Si(111)-(3×1) surface suggest that this surface has a (3×2) periodicity instead of the (3×1) periodicity reported in the literature. By considering the energy shift and intensity of each Si 2p surface component, we conclude that the structure of the (3×2) phase is basically the same as that of the HCC model, but with a Ca coverage of 1⁄6 ML. Regarding the valence-band, five surface states, none of which crosses the Fermi level, were observed in the bulk band gap. The dispersion features of three of them agree well with those of monovalent atom adsorbed Si(111)-(3×1) surfaces along the chain direction. The two other states observed in the band gap have not been reported in the literature, and they are interpreted as surface states that are peculiar to the Ca/Si(111)-(3×2) surface due to the 1⁄6 ML coverage. Regarding the Ag/Si(111) surface, a new c(12×2) phase is observed in LEED after cooling the room temperature (6×1) phase to 70 K. In the Si 2p core-level spectra and in the valence band spectra, no significant difference is observed between the two surfaces. Further, the origins of the Si 2p surface components and the surface states of these surfaces are well explained using the HCC model. These results indicate that the basic structure of this Ag/Si(111) surface is quite similar with the HCC model but with a c(12×2) periodicity, and that the (6×1) structure results from thermal vibrations of the surface atoms. [DOI: 10.1380/ejssnt.2004.210]
