Strain-Modulated Adatom and Surface Vacancy Pair Interactions

Abstract

Adsorbed atoms (adatoms) and vacancies have a significant role to play in the physics of surfaces and the mechanisms of film growth on a substrate. This paper investigates the effect of applied or residual strain on the energetic interaction between pairs of adatoms and vacancies. The analysis is based on a continuum-level point-defect model, where adatoms and vacancies have strain-dependent properties. Atomistic calculations are used to evaluate the defect properties for Si(111). The result is used as input for the defect model in order to investigate the strength and character of the interaction versus strain, separation distance, and relative orientation of the defects. It is found that strain may cause the defects to align in certain direction and modulate their interaction between repulsion and attraction, providing a mechanism for controlled building of nanostructures.

Simulation of adatom clustering on a stepped surface

“…The position of adatom I is described by a vector x I ¼ x I i e i . Throughout the paper, Einstein's summation convention is adopted for all repeated Latin indices (1, 2, 3) and Greek indices (1,2).…”

“…Surface processes, such as material deposition onto a substrate and self-assembly of adatoms, molecules and nanoparticles on a surface, have attracted increasingly intensive attention owing to their extensive applications in the development of nanostructured materials and devices [1]. Study of interaction and evolution behaviour of adatoms is fundamental to many surface phenomena since adatoms may interact to form clusters or islands and, hence, eventually determine the surface morphology and quality of materials.…”