Hug-like island growth of Ge on strained vicinal Si(111) surfaces

TL;DR

This study investigates the formation and evolution of Ge nanoislands on strained vicinal Si(111) surfaces, revealing how substrate misorientation influences island shape and strain relaxation dynamics.

Contribution

It demonstrates the direct formation of Ge nanoislands via elastic relaxation during step-flow growth and links island shape changes to substrate miscut angles using simulations.

Findings

Nanoislands form through elastic relaxation at step edges.

Island shape transformation depends on substrate miscut angle.

Strain relaxation anisotropy governs islanding dynamics.

Abstract

We examine the structure and the evolution of Ge islands epitaxially grown on vicinal Si(111) surfaces by scanning tunneling microscopy. Contrary to what is observed on the singular surface, three-dimensional Ge nanoislands form directly through the elastic relaxation of step-edge protrusions during the unstable step-flow growth. As the substrate misorientation is increased, the islands undergo a shape transformation which is driven by surface energy minimization and controlled by the miscut angle. Using finite element simulations, we show that the dynamics of islanding observed in the experiment results from the anisotropy of the strain relaxation.