Modelling multi-scale material growth and erosion under energetic atomic deposition

Abstract

ABSTRACT We study crystalline surface evolution in extreme environments, where high-energy atoms impinge on a crystalline surface to cause sputtering, growth and surface roughening. For our model system, we study the evolution of the Ni(111) surface under Ni atom bombardment, using Molecular Dynamics (MD) simulation and a Sutton-Chen force field, where the uppermost surface layers are free to move, supported by thermostatically controlled layers above a rigid template. The MD statistics of sputtering and sticking are used to aid the development of a computationally efficient kinetic Monte Carlo (KMC) code. Comparisons between the simulation surface morphologies are used to tune the KMC growth rules so that the key statistical features of the MD structures are captured by the KMC model. This model is then employed to explore the predicted behaviour over length and times scales much larger than those accessible to MD. While the MD-KMC approach is well known, this application to the complex surface growth encountered in energetic atomic bombardment illuminates the complexities of relating atomistic events to morphological evolution. The work shows how simulation methodology can be extended to provide predictive capabilities, paving the way for design tools for engineering processes such as plasma deposition film growth.