SI(110)16X2 AND SI(110)2X3-SB SURFACES STUDIED BY PHOTOEMISSION AND OPTICAL SPECTROSCOPY

The electronic properties of clean Si(110)16 x 2 and Si(110)2 x 3-Sb s urfaces have been studied by angle resolved ultraviolet photoelectron spectroscopy (ARUPS) and surface differential reflectivity (SDR). For the clean 16 x 2 surface four surface states have been recognized by A RUPS and their dispersions have been mapped along the main symmetry li nes in the surface Brillouin zone, SDR experiments revealed transition s between filled and empty surface states at similar to 1.8, 2.4 and 2 .9 eV. Antimony has been subsequently evaporated (about one monolayer) thus obtaining a 2 x 3 reconstruction. The surface electronic structu re resulted to be strongly modified with three surface state bands obs erved in ARUPS along the <[(1)over bar 11]> direction and no optical t ransitions detected by SDR in bur energy range (1.3-3.5 eV).