Producing nanodot arrays with improved hexagonal order by patterning surfaces before ion sputtering

TL;DR

Prepatterning surfaces before ion sputtering significantly enhances the hexagonal order of nanodot arrays by influencing initial surface conditions, leading to more ordered nanostructures.

Contribution

This study demonstrates that specific initial surface patterns can improve the hexagonal order of nanodots formed by ion sputtering, extending previous models with practical prepatterning strategies.

Findings

Prepatterned surfaces increase hexagonal order of nanodots.

Optimal initial wavelength is about equal or double the natural wavelength.

Scratches with width less than the natural wavelength improve order.

Abstract

When the surface of a nominally flat binary material is bombarded with a broad, normally-incident ion beam, disordered hexagonal arrays of nanodots can form. Shipman and Bradley have derived equations of motion that govern the coupled dynamics of the height and composition of such a surface [P. D. Shipman and R. M. Bradley, Phys. Rev. B 84, 085420 (2011)]. We investigate the influence of initial conditions on the hexagonal order yielded by integration of those equations of motion. The initial conditions studied are hexagonal and sinusoidal templates, straight scratches and nominally flat surfaces. Our simulations indicate that both kinds of template lead to marked improvements in the hexagonal order if the initial wavelength is approximately equal to or double the linearly selected wavelength. Scratches enhance the hexagonal order in their vicinity if their width is close to or less than the linearly selected wavelength. Our results suggest that prepatterning a binary material can dramatically increase the hexagonal order achieved at large ion fluences.