Reinvestigation of the band structure of the Si(111)5 X 2-Au surface

The electronic band structure of the Si(111)5x2-Au surface is reinvestigated in detail by angle-resolved photoelectron spectroscopy (ARPES), especially for the surface-state bands near the Fermi energy. Through extensive ARPES measurements and analyses, four different surface-state bands are identified within the bulk band gap, the dispersions of which are determined. It was clearly shown that the Si(111)5x2-Au surface is semiconducting at room temperature with a band gap larger than similar to0.2 eV in contrast with previous ARPES results. Furthermore, the band dispersions determined are not compatible with a Peierls-gap idea proposed recently.