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The deposition and annealing of Tb on Si surfaces leads to a variety of fascinating nanostructures from zero-dimensional clusters on Si(111) over one-dimensional nanowires on Si(001) to well ordered two- and three-dimensional Tb silicide layers on Si(111). The metallic Tb disilide monolayer on Si(111) is especially interesting since its formation pins the Fermi level near the Si conduction band minimum making it interesting for ohmic contacts on n-type Si. Its electronic structure near the Fermi level is characterized by sharp bands forming a hole pocket at $\overline{\Gamma}$ and strongly anisotropic electron pockets at the $\overline{\mathrm{M}}$ points. For monolayer depositions on Si(hhk) surfaces being vicinal to Si(111), the formation of nanowires with widths depending on the offcut angle is expected.
In this work, the growth and the electronic structure of such Tb disilicide nanowires on vicinal Si(111) surfaces were studied with scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES). In general, narrower Tb disilicide structures are observed for larger offcut angles, but the morphology of these structures strongly depends on the offcut direction. For Si(hhk) surfaces with h < k, the silicide forms well defined nanowires with sharp edges while only irregular stripes are formed for h > k.
Nevertheless, the characteristic two-dimensional electronic structure of the disilicide monolayer is observed with ARPES on all vicinal surfaces. Thereby, the bands, which were sharp for the extended monolayer on planar Si(111), broaden in the direction perpendicular to the step edges due to the confinement of the silicide structures to finite widths. This effect is quantified by an analysis of the electron pockets at the $\overline{\mathrm{M}}$ points.
Furthermore, electronically purely one-dimensional bands emerge for low Tb coverage on Si(335). Tb silicide structures possibly corresponding to these bands are discussed.
