Electronic structure ofSn/Si(111)3×3: Indications of a low-temperature phase

The $\mathrm{S}\mathrm{n}/\mathrm{S}\mathrm{i}\left(111\right)\mathrm{}$ $\sqrt{3}\times \sqrt{3}$ surface has been studied by photoelectron spectroscopy, low-energy electron diffraction (LEED), and scanning tunneling microscopy. Unlike Sn/Ge(111), the Sn/Si(111) surface shows a $\sqrt{3}\times \sqrt{3}$ LEED pattern at low temperature also (70 K). The electronic structure, however, is inconsistent with a pure $\sqrt{3}\times \sqrt{3}$ phase. Sn $4d$ spectra exhibit two major components and the valence band shows two surface bands. These features have been associated with the low-temperature $3\times 3$ phase in the case of Sn/Ge(111). The similarity in the electronic structure points to stabilization of a low-temperature phase for Sn/Si(111) also, but at a significantly lower temperature (<70 K).