Formation of ripple pattern on silicon surface by grazing incidence ion beam sputtering

TL;DR

This study investigates how grazing incidence ion beam sputtering induces ripple patterns on silicon surfaces, revealing that surface roughening and incident angle influence ripple orientation and quality.

Contribution

It demonstrates that chemical roughening enables ripple formation at grazing angles with perpendicular wave vectors, expanding understanding of surface patterning mechanisms.

Findings

Ripple patterns form at grazing incidence with perpendicular orientation.

Surface roughening facilitates ripple initiation under specific conditions.

Ripple quality correlates with initial roughness and ion fluence.

Abstract

Off-normal low energy ion beam sputtering of solid surfaces often leads to morphological instabilities resulting in the spontaneous formation of ripple structures in nanometer length scales. In the case of Si surfaces at ambient temperature, ripple formation is found to take place normally at lower incident angles with the wave vector parallel to the ion beam direction. The absence of ripple pattern on Si surface at larger angles is due to the dominance of ion beam polishing effect. We have shown that a gentle chemical roughening of the starting surface morphology can initiate ripple pattern under grazing incidence ion beam sputtering, where the ripple wave vector is perpendicular to the ion beam direction. The characteristics of the perpendicular mode ripples are studied as a function of pristine surface roughness and ion fluence. The quality of the morphological structure is assessed from the analysis of ion induced topological defects.