Unusual pattern formation on Si(100) due to low energy ion bombardment

TL;DR

This study investigates how silicon surfaces develop unusual patterns when bombarded with low energy argon ions at high oblique angles, revealing transitions from ripples to smooth surfaces due to erosion and viscous flow effects.

Contribution

It provides new insights into the pattern formation mechanisms on silicon surfaces under low energy ion bombardment at high incident angles.

Findings

Parallel ripples up to 67°

Transition to perpendicular ripples at 80°

Complete surface smoothening beyond 80°

Abstract

In this paper evolution of silicon surface topography, under low energy ion bombardment, is investigated at higher oblique incident angles in the range of 63\degree-83\degree. Si(100) substrates were exposed to 500 eV argon ions. Different surface morphology evolves with increasing angle of incidence. Parallel-mode ripples are observed up to 67\degree which undergo a transition to perpendicular-mode ripples at 80\degree. However, this transition is not a sharp one but undergoes a series of unusual pattern formation at intermediate angles. Complete smoothening of silicon surface is observed at incident angles beyond 80\degree. The observed patterns are attributed to surface confined viscous flow and sputter erosion under ion bombardment.