Nucleation and evolution of the Au-induced 5×2 structure on vicinal Si(111)

Abstract

Topographical changes on vicinal Si(111)have been followed as a function of submonolayer Au coverage. Nucleation at step edges leads to subsequent growth of a single-domain overlayer of the Auinduced 5X2 structure. Phase boundaries between step, 7X7 and 5X2 regions have been studied, as well as the detailed structure of the step and 5 X2 regions. Gradual changes in facet angle on the surface occurred, driven by 5X2 terrace growth. An inhomogeneous coverage of Au was observed, with a pattern extending over distances on the order of micrometers, indicating large-scale surface diffusion of both Au and Si atoms.

First-principles study of the atomic and electronic structure of theSi(111)−(5×2)−Ausurface reconstructio

“…Therefore, three different domains are possible for the 5×2 reconstruction on the flat Si(111) surface. Singledomain surfaces, necessary for ARPES, can be fabricated using vicinal surfaces with a slight cut-off angle [5,23]. The presence of one-dimensional structures in this reconstruction has also been confirmed by the ARPES studies.…”

“…This, together with the uncertainties arising from the use of the local approximation to the density functional theory, make difficult to draw definitive conclusions solely based on the energetics. The comparison of the calculated band structures and local density of states, respectively, with the available ARPES data [28,29,30] and the STM images [23,24,34] becomes then instrumental in order to identify the most plausible candidates for the equilibrium structure. In the following we summarized some our main conclusions:…”

“…The STM images are characterized by the presence of bright, irregular protrusions [24,25], and "Y"-shaped features [23,35] with a well defined orientation respect to the underlying substrate. The protrusions have been established to be silicon adatoms [36], which are present on the surface with an optimum coverage close to 1/4 adatoms per 5×2 unit cell.…”

“…It was first discovered about thirty years ago [18,19,20] and has been investigated using many experimental techniques since then. This includes low energy electron diffraction (LEED) studies [18,19,20], x-ray diffraction [21] and x-ray standing wave analysis [22], scanning tunneling microscopy (STM) [23,24,25], angle resolved photoemission spectroscopy (ARPES) [26,27,28,29,30] and inverse photoemission [31], and high resolution electron microscopy (HREM) combined with heavy-atom holography [32].…”

Colloquium: Electronic instabilities in self-assembled atom wires

“…Moreover, no phase transition has been observed in this system. Attention has therefore shifted to other Auinduced quasi-1D reconstructions on vicinal Si͑111͒ surfaces ͑Stevens et al., 1993;O'Mahony et al, 1994;Jało-chowski et al, 1997͒, which do exhibit clear signs of electronic instabilities as discussed in the following sections.…”