Shape Selection in Nanopillar Formation

TL;DR

This paper uses Vicinal Cellular Automata modeling to explain how local and global growth potentials influence the formation of diverse nanopillar shapes, and how growth parameters can be manipulated to control surface morphologies.

Contribution

It introduces a model linking surface potential distribution to nanopillar shape formation, offering insights into controlling surface morphologies via growth parameters.

Findings

Local potentials lead to symmetry-following structures

Global potentials produce spherical or oval shapes

Temperature and flux control surface patterning

Abstract

Crystal growth processes produce a diverse array of surface formations, primarily distinguished by their geometric shapes. While some structures strictly adhere to the underlying crystal symmetry, others exhibit universal circular or oval geometries. Utilizing Vicinal Cellular Automata (VicCA) modeling, we demonstrate that these morphological differences depend on the spatial distribution of the growth potential. Specifically, local potential variations concentrated around surface steps drive the formation of the lattice symmetry - following structures, whereas global potentials - often originating from defects-generate universal spherical or oval shapes. Furthermore, we illustrate how these morphologies are influenced by the growth parameters such as sticking coefficient or diffusion coefficient. Although the positioning of surface defects is difficult to control, we show that temperature and external particle flux can be effectively used to steer and manipulate surface pattern formation.