Strong anisotropy in surface kinetic roughening: analysis and experiments

TL;DR

This paper experimentally investigates anisotropic surface kinetic roughening in silicon surfaces subjected to ion-beam sputtering, confirming the applicability of a recently proposed anisotropic scaling Ansatz for analyzing surface roughness.

Contribution

It validates a new anisotropic scaling framework for surface roughness analysis through experimental data on silicon surfaces, enhancing understanding of anisotropic kinetic roughening.

Findings

Confirmation of strong anisotropic roughening in experiments

Validation of the anisotropic scaling Ansatz for 2D surface observables

Identification of measurement issues affecting anisotropic scaling assessment

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 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.