Stability analysis of a viscoelastic model for ion-irradiated silicon

Abstract

To study the effect of stress within the thin amorphous film generated atop Si irradiated by Ar+, we model the film as a viscoelastic medium into which the ion beam continually injects biaxial compressive stress. We find that at normal incidence, the model predicts a steady compressive stress of a magnitude comparable to experiment. However, linear stability analysis at normal incidence reveals that this mechanism of stress generation is unconditionally stabilizing due to a purely kinematic material flow, depending on none of the material parameters. Thus, despite plausible conjectures in the literature as to its potential role in pattern formation, we conclude that beam stress at normal incidence is unlikely to be a source of instability at any energy, supporting recent theories attributing hexagonal ordered dots to the effects of composition. In addition, we find that the elastic moduli appear in neither the steady film stress nor the leading order smoothening, suggesting that the primary effects of stress can be captured even if elasticity is neglected. This should greatly simplify future analytical studies of highly nonplanar surface evolution, in which the beam-injected stress is considered to be an important effect.

References in corpus (4)

• On the stabilization of ion sputtered surfaces
• Is keV ion induced pattern formation on Si(001) caused by metal impurities?
• Hydrodynamic approach to surface pattern formation by ion beams
• Ion induced solid flow

Cited by in corpus (6)

• Solid flow drives surface nanopatterning by ion-beam irradiation
• Stress-induced patterns in ion-irradiated Silicon: a model based on anisotropic plastic flow
• The crater function approach to ion-induced nanoscale pattern formation: Craters for flat surfaces are insufficient
• Crater functions for compound materials: a route to parameter estimation in coupled-PDE models of ion bombardment
• Morphological Transitions in Nanoscale Patterns Produced by Concurrent Ion Sputtering and Impurity Co-deposition
• PyCraters: A Python framework for crater function analysis