Strong anisotropy in surface kinetic roughening: Analysis and experiments

Abstract

We report an experimental assessment of surface kinetic roughening properties that are anisotropic in space. Working for two specific instances of silicon surfaces irradiated by ion-beam sputtering under diverse conditions (with and without concurrent metallic impurity codeposition), we verify the predictions and consistency of a recently proposed scaling Ansatz for surface observables like the two-dimensional (2D) height power spectral density (PSD). In contrast with other formulations, this ansatz is naturally tailored to the study of two-dimensional surfaces, and allows us to readily explore the implications of anisotropic scaling for other observables, such as real-space correlation functions and PSD functions for 1D profiles of the surface. Our results confirm that there are indeed actual experimental systems whose kinetic roughening is strongly anisotropic, as consistently described by this scaling analysis. In the light of our work, some types of experimental measurements are seen to be more affected by issues like finite space resolution effects, etc. that may hinder a clear-cut assessment of strongly anisotropic scaling in the present and other practical contexts.

Self-organized nanopatterning of silicon surfaces by ion beam sputtering

“…Another nontrivial interplay is that between spatial order in the patterns produced and spatial disorder, as induced by the pervasive conditions that enhance kinetic roughening. Recent indications exist [300] that the prevalence of one of these effects over the other (order vs disorder), and the form in which it takes place, may actually place constraints on the type of interfacial equation that is appropriate, and thus guide in the development of an accurate continuum description of the process.…”

Ion damage overrides structural disorder in silicon surface nanopatterning by low-energy ion beam sputtering

“…However, although the technique has been already known for half a century, its underlying mechanisms are still under debate [5]. Hence, from a basic point of view, IBS-induced structures still pose challenging questions on the dynamics of surface patterns at the nanoscale, including issues on pattern order [8], coarsening [9], and kinetic roughening [10].…”

Strong anisotropy in two-dimensional surfaces with generic scale invariance: Nonlinear effects

“…1D correlations like G x,y , or power spectral densities of 1D profiles S x,y . We have moreover shown how all these results can be employed in a consistent characterization of SA for actual experimental data on IBS-sputtered silicon surfaces [21].…”