14 research outputs found
The phase diagram of the lattice Calogero-Sutherland model
We introduce a {\it lattice} version of the Calogero Sutherland model adapted
to describe pairwise interacting steps with discrete positions on a
vicinal surface. The configurational free energy is obtained within a transfer
matrix method. The full phase diagram for attractive and for repulsive
interaction is deduced. For attraction, critical temperatures of faceting
transitions are found to depend on step density.Comment: latex PRBCalogSuth.tex, 6 files, 4 pages [SPEC-S00/900
Vicinal silicon surfaces: from step density wave to faceting
This paper investigates faceting mechanisms induced by electromigration in
the regime where atomic steps are transparent. For this purpose we study
several vicinal orientations by means of in-situ (optical diffraction,
electronic microscopy) as well as ex-situ (AFM, microprofilometry)
visualization techniques. The data show that faceting proceeds in two stages.
The first stage is short and leads to the appearance of a step density wave,
with a wavelength roughly independent of the surface orientation. The second
stage is much slower, and leads to the formation of a hill-and-valley
structure, the period of which depends on the initial surface orientation. A
simple continuum model enables us to point out why the wavelength of the step
density wave does not depend on the microscale details of the surface. The
final wavelength is controlled by the competition between elastic step-step
interaction and facet edge energy cost. Finally, the surface stress angular
dependence is shown to emerge as a coarsed-grained picture from the step model.Comment: 26 pages, 9 figure
Diffraction of He from Cu(110) in the 20–40 meV range; comparison with a realistic model potential
Erratum to “Statistical analysis of STM images and measurement of the step-step interaction on Cu vicinal surfaces” [Surface Science 317 (1994) L1115]
Probing surfaces with thermal He atoms: scattering and microscopy with a soft touch
Helium atom scattering (HAS) is a well established technique, particularly suited for the investigation of insulating and/or fragile materials and light adsorbates including hydrogen. In contrast to other beam techniques based on Xrays or electrons, low energy (typically less than 100 meV) He atoms are scattered
by the tail of the electron density distribution which spill out from a surface, therefore HAS is strictly a nonpenetrating technique without any sample damage. HAS
has been used to investigate structural properties of crystalline surfaces, including precise determination of atomic step heights, for monitoring thin film growth, to
study surface transitions such as surface melting and roughening and for determining the presence and properties of adsorbates. Energy resolved HAS can provide
information about surface vibrations (phonons) in the meV range and surface diffusion.
This chapter provides a brief introduction to HAS with an outlook on a new, promising surface science technique: Neutral Helium Microscopy