ANGLE-RESOLVED PHOTOEMISSION-STUDY OF A SINGLE-DOMAIN SI(001)2X1-NA SURFACE WITH SYNCHROTRON-RADIATION

The electronic structures of a single-domain Si(001)2 X 1-Na surface a t a saturation coverage have been studied by angle-resolved photoelect ron spectroscopy (ARPES) with linearly polarized synchrotron radiation (SR). To determine the dispersion of surface states in detail, the AR PES spectra have been measured along several symmetry axes of the 2 X 1 surface Brillouin zone. The result revealed a new assignment of surf ace-state dispersions. Symmetry properties of upper surface-state band s are determined using a linearly polarized character of SR. It has be en found that the upper two surface states have the same symmetries as the dangling bond of the clean Si(001)2 X 1 dimer surface. The electr onic structure of the Si(001)2 X 1-Na surface determined here is very similar to that of the Si(001)2 X 1-K surface [Surf. Sci. 261 (1992) 2 17] and is consistent with that expected for an alkali double-layer mo del.