Prepyramid-to-pyramid transition of SiGe islands on Si(001)

TL;DR

This study investigates the morphological evolution of SiGe islands on Si(001) during strained growth, revealing a transition from rough mounds to facetted pyramids, supported by microscopy and theoretical modeling.

Contribution

It provides detailed experimental evidence of the shape transition of SiGe islands and confirms the predictions of a recent theoretical model.

Findings

Islands transition from unfacetted mounds to facetted pyramids

High-resolution microscopy reveals shape evolution with size

Results agree with theoretical predictions

Abstract

The morphology of the first three-dimensional islands appearing during strained growth of SiGe alloys on Si(001) was investigated by scanning tunneling microscopy. High resolution images of individual islands and a statistical analysis of island shapes were used to reconstruct the evolution of the island shape as a function of size. As they grow, islands undergo a transition from completely unfacetted rough mounds (prepyramids) to partially {105} facetted islands and then they gradually evolve to {105} facetted pyramids. The results are in good agreement with the predictions of a recently proposed theoretical model.