MG-INDUCED SI(111)3X1 STRUCTURE STUDIED BY PHOTOELECTRON-SPECTROSCOPY

By means of angle resolved photoelectron spectroscopy using synchrotron radiation, we have measured the valence band and surface sensitive Si2p core-level spectra for the Si(111)3 X 1-Mg surface. The dispersion of the valence band shows the fact that this surface has a semiconducting property and two surface states in the projected bulk band gap at the ($) over bar K point. From the fitting results of the Si2p core-level spectra, we find that the two surface shifted core-level components, S'(1) and S'(2) stem from the Si atom with single dangling bond and the Si atom bonding to the Mg atom, respectively. From experimental observations we suggest that the Si(111)3 X 1-Mg structure is formed by ordering of Mg atoms on the ideal Si(111)1 X 1 surface, not by reconstruction of Si atoms of the substrate.