Defect-Induced Instability of the Surface Layer Involving Static Coupled Lamb and Rayleigh Waves as a Universal Mechanism of the Formation of an Ensemble of Nanodot Nucleation Centersстатья
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Дата последнего поиска статьи во внешних источниках: 29 ноября 2013 г.
Аннотация:It is demonstrated that a stressed flat surface nanolayer saturated with mobile point defects exhibits
a threshold (with respect to the defect concentration or mechanical stress) transition to a periodic spatially bent
state with a simultaneous formation of the spatially periodic defect pile-ups at the extrema of the spontaneously
emerging surface relief. In this case, the layer deformation corresponds to the displacements in a static bending
Lamb wave and the deformation of the underlying elastic continuum corresponds to the displacements in the
static Rayleigh wave. For the first time, we demonstrate that the analysis simultaneously involving the nonlocal
character of the defect interaction with the lattice atoms and both (normal and lateral) defect-induced forces that
cause the bending of the surface layer yields two maxima on the curve of the instability growth rate versus the
period of the generated relief. This corresponds to the experimentally observed two scales of the surface relief
modulation upon the laser and ion irradiation of semiconductors. Based on the results obtained, we propose a
cooperative defect–deformational (DD) mechanism for the formation of an ensemble of the nanoparticle nucleation
centers above the critical levels of the stress or the defect concentration. An approach to the calculation
of a bimodal distribution function of the nanoparticle nucleation centers with respect to their size is adequately
developed to the DD mechanism of nucleation which represents the distribution function in terms of the growth
rate. The calculated results are compared with the experimental data for the molecular beam epitaxy of the nanodot
ensemble and the pulsed laser nanostructuring of a solid surface