Growth and characterization of Tb silicide nanostructures on Si(hhk) substrates

The growth of Tb-induced nanostructures on vicinal Si(111) substrates with an offcut toward the $\left[11\overline{2}\right]$ direction, so-called Si(hhk) substrates, was studied. The nanostructures were analyzed using scanning tunneling microscopy and spectroscopy as well as core-level photoemission spectroscopy. For low Tb coverages, terraces covered by a Tb-induced submonolayer structure are observed. At higher coverages, metallic Tb disilicide monolayer structures are dominant. Their appearance strongly depends on the offcut direction. Well-defined nanowires with straight edges are only present for Si(hhk) substrates with $h<k$. Furthermore, only these substrates may host very narrow metallic nanolines. In general, narrower nanostructures are observed for larger offcut angles enabling the formation of Tb disilicide nanowires with average widths as low as $2.3\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$ for Si(335) substrates.