📝 SummarXiv

Abstract

A first-principles understanding of the self-organization of highly regular, nanometer-scale structures atop irradiated semiconductor surfaces has been sought for decades. While numerous models exist which explain certain aspects of this phenomenon, a unified, physical model capable of explaining all details of pattern formation has remained elusive. However, it is increasingly apparent that such a model will require understanding the dual influence of the collision cascade initiated by ion implantation: first, as a source of material transport by sputtering and atomic displacements occurring over short time scales, and, second, as a source of defects permitting viscous flow within the thin, amorphous layer that results from sustained irradiation over longer time scales. To better understand the latter, we develop several asymptotic approximations for coupling the localized ion dose with an evolving free interface. We then show how theoretical predictions of quantities commonly used for comparison with experimental observations -- such as ripple wavelengths, critical irradiation angle for patterning onset, and surface roughening -- exhibit surprising sensitivity to the details of this coupling.