Ion induced solid flow

TL;DR

This paper proposes a new perspective that models amorphous solids under ion beam sputtering as highly viscous liquids, explaining nanostructure formation and enabling better control of nanoscale surface patterning.

Contribution

It introduces a viscous liquid flow model for amorphous solids under ion irradiation, challenging previous erosion-focused explanations and advancing understanding of nano-pattern formation.

Findings

Flow model explains complex morphological phase diagram

Erosion plays a subsidiary role in pattern formation

Enables controllable nanostructuring via solid flow

Abstract

Amorphous solids can flow over very long periods of time. Solid flow can also be artificially enhanced by creating defects, as by Ion Beam Sputtering (IBS) in which collimated ions with energies in the 0.1 to 10 keV range impact a solid target, eroding its surface and inducing formation of nanometric structures. Recent experiments have challenged knowledge accumulated during the last two decades so that a basic understanding of self-organized nano-pattern formation under IBS is still lacking. We show that considering the irradiated solid to flow like a highly viscous liquids can account for the complex IBS morphological phase diagram, relegating erosion to a subsidiary role and demonstrating a controllable instance of solid flow at the nanoscale. This new perspective can allow for a full harnessing of this bottom-up route to nanostructuring.