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We have investigated the 6H-SiC(0001) √3×√3 R30° and 3×3 surfaces using the valence band spectra and the workfunction change as a function of the Na coverage. The Na-induced ionization energy shift of the √3×√3 R30° surface at the minimum value of the workfunction is in good agreement with the calculated one based on the Si-T4 model in which Na is adsorbed at all DBs. Similar workfunction changes suggest that the 6H-SiC(0001) 3×3 surface has the same density of reactive sites (1/3 ML) as the √3×√3 R30° surface. This result is interpreted in the framework of current models of the 3×3 reconstruction. In particular, we show that the results are not compatible with the accepted Erlangen-Jena model.

The Ag-adsorbed Si(110)2×16 surfaces were investigated using low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES). When Ag was deposited on a Si(110)2×16 surface at room temperature (RT) and annealed at several elevated temperatures, diffuse 1×1, 1×2+streak, 1×2, and (-1, 6)×(-7, 0) structures were observed by LEED. The relative Ag coverage of the reconstructed structures were estimated from Ag(MNN)/Si(LVV) AES intensity ratios and previous results. The structural model of the Ag/Si(110)1×2 surface was proposed from the LEED and AES results.

We have investigated the Sb-induced phase transition of the reconstructed Si(112) surface by low energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). A sharp sixfold hexagonal LEED pattern was observed when Sb was deposited on the clean Si(112) surface at 300°C, corresponding to the bulk-terminated 1×1 structure of the Si(111) surface. From the LEED pattern and the XPS results, we suggest a surface structure corresponding to the LEED pattern with (111) - 1×1 + weak 5×1 spots for the Sb/Si(112) surface.