Growth of metallic nanowires on anisotropic Si substrates : Pb on vicinal Si(001), Si(755), Si(533), and Si(110)

The spontaneous formation of mesoscopic Pb-wires, on 4 degrees off-cut Si(0 0 1) vicinal surface, Si(7 5 5), Si(5 3 3), and Si(1 1 0) substrates was s tudied by low-energy electron microscopy. Before the deposition of Pb the s ubstrates were modified by predeposition of a submonolayer amount of Au fol lowed by annealing. The Au-induced reconstruction creates quasi-one-dimensi onal facets and superstructures. Their width ranged from several hundred nm in the case of the vicinal Si(0 0 1) down to atomic scale size, for the Si (1 1 0) surface. The best-developed arrays of parallel aligned mesoscopic w ires were obtained during the deposition of Pb on substrates cooled slightl y below room temperature. Wires with length to width ratio reaching 130 wer e produced on the Si(7 5 5) and the Si(5 3 3) substrates. The width of thes e nanowires was uniform over the whole substrate and was about 60 nm. The d riving forces for the formation of the mesoscopic wires are the anisotropic strain due to the large misfit between the Pb and the Si lattice and one-d imensional diffusion of Pb. (C) 2001 Elsevier Science B.V. All rights reser ved.