Evidence of electron confinement in the single-domain (4×1)-In superstructure on vicinal Si(111)

Reflectance anisotropy spectroscopy is applied to submonolayer growth of In on the vicinal silicon (111) surface. Deposition in the region of 1 monolayer onto a clean stepped Si(111) surface at elevated temperature produces a single-domain In-induced (4×1) superstructure consisting of quasi-one-dimensional chains aligned parallel to the vicinal surface step edges. A significant optical anisotropy (1.65%), uncharacteristic of semiconductor systems, develops in the region of 1.9 eV which saturates upon completion of the (4×1) superstructure. We relate this feature to an optical transition involving a flat, highly populated filled surface state observed previously. We argue that the intensity and direction of this peak are indicative of electronic confinement within this system perpendicular to the In-induced chain length.