Interplay between Morphology and Surface Transport in Nanopatterns Produced by Ion-Beam Sputtering
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1059-KK01-06
Interplay between Morphology and Surface Transport in Nanopatterns Produced by IonBeam Sputtering Rodolfo Cuerno1, Javier Muñoz-García2, Mario Castro3, Raúl Gago4, and Luis Vázquez5 1 Departamento de Matemáticas and GISC, Universidad Carlos III de Madrid, Avenida de la Universidad 30, Leganés (Madrid), E-28911, Spain 2 Departamento de Matemáticas and GISC, Universidad de Castilla la Mancha, Ciudad Real, E13071, Spain 3 Escuela Técnica Superior de Ingeniería (ICAI) and GISC, Universidad Pontificia Comillas de Madrid, Madrid, E-28015, Spain 4 Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Madrid, E-28049, Spain 5 Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Madrid, E-28049, Spain ABSTRACT A "hydrodynamic" model has been proposed to describe nanopattern formation and dynamics on amorphous surfaces eroded by ion-beam sputtering (IBS), that relates to descriptions of pattern formation in macroscopic systems such as aeolian sand dunes. At variance with previous continuum models of the morphology of ion-sputtered surfaces, the dynamics of the species that diffuse along the surface is coupled in a natural way to that of the surface height. We report recent results for this model, considering normal and oblique ion incidence, for both fixed and rotating targets, and include comparison to recent experiments on silicon. Effective interface equations can be obtained, that generalize the anisotropic Kuramoto-Sivashinshy equation through additional conserved Kardar-Parisi-Zhang type nonlinear terms. In general dot or ripple patterns form, that later evolve exhibiting complex nonlinear dynamics. Thus, we observe interrupted coarsening behavior such that, for normal incidence, domains of hexagonally ordered structures appear, that compare favorably with those obtained in many experiments of nanodot formation by IBS. In other parameter regions, this short-range ordered patterns coexist with long range disorder and kinetic roughening. For oblique incidence, a ripple pattern is generically obtained that also shows interrupted coarsening and other nonlinear features like nonuniform transverse motion, again reproducing experimental observations. INTRODUCTION Materials nanostructuring by ion-beam sputtering (IBS) has received increased attention in recent years [1-3], due to the potential of this bottom-up procedure for applications in Nanotechnology, and also due to the interesting issues it arises in the wider context of Pattern Formation at submicrometer scales [4]. In these experiments, a target is irradiated by a collimated beam of energetic ions (typical energies being in the keV range) that impinge onto the former under a well defined angle of incidence. Although routinely employed since long for many diverse applications within Materials Science (material implantation, sample preparation, etc.) the capabilities of this technique for efficient nanopatterning have been recognized only recently, see references in [1-3]. Thus, it induces self-orga
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