Electronic structure of Sn/Si(111) √3X√3:: Indications of a low-temperature phase

The Sn/Si(111) root 3 x root 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 root 3 x root 3 LEED pattern at low temperature also (70 K). The electronic structure, however, is inconsistent with a pure root 3 x root 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 x 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(lll) also, but at a significantly lower temperature (< 70 K).