Nanoscale dynamics during self-organized ion beam patterning of Si: I. Ar$^+$ Bombardment

TL;DR

This study uses advanced X-ray scattering techniques to analyze the nanoscale surface dynamics of silicon during ion beam patterning, revealing complex transition behaviors and correlations with nonlinear growth models.

Contribution

It provides new insights into the fluctuation dynamics and transition from linear to nonlinear behavior during silicon nanopatterning by Ar$^+$ bombardment.

Findings

Surface dynamics exhibit stretched and compressed exponential decay.

Correlation times peak at ripple wavelength.

Behavior aligns with nonlinear growth model simulations.

Abstract

Coherent grazing-incidence small-angle X-ray scattering is used to investigate the average kinetics and the fluctuation dynamics during self-organized nanopatterning of silicon by Ar$^+$ bombardment at 65$^{\circ}$ polar angle. At early times, the surface behavior can be understood within the framework of linear theory. The transition away from the linear theory behavior is observed in the dynamics through the intensity correlation function. It quickly evolves to exhibit stretched exponential decay on short length scales and compressed exponential decay on length scales corresponding the dominant structural length scale - the ripple wavelength. The correlation times also peak strongly at the ripple length scale. This behavior has notable similarities but also significant differences with the phenomenon of de Gennes narrowing. Overall, this dynamics behavior is found to be consistent with simulations of a nonlinear growth model.