Morphological evolution of pit-patterned Si(001) substrates driven by surface-energy reduction

Research output: Contribution to journalResearch articleContributedpeer-review

Abstract

Lateral ordering of heteroepitaxial islands can be conveniently achieved by suitable pit-patterning of the substrate prior to deposition. Controlling shape, orientation, and size of the pits is not trivial as, being metastable, they can significantly evolve during deposition/annealing. In this paper, we exploit a continuum model to explore the typical metastable pit morphologies that can be expected on Si(001), depending on the initial depth/shape. Evolution is predicted using a surface-diffusion model, formulated in a phase-field framework, and tackling surface-energy anisotropy. Results are shown to nicely reproduce typical metastable shapes reported in the literature. Moreover, long time scale evolutions of pit profiles with different depths are found to follow a similar kinetic pathway. The model is also exploited to treat the case of heteroepitaxial growth involving two materials characterized by different facets in their equilibrium Wulff's shape. This can lead to significant changes in morphologies, such as a rotation of the pit during deposition as evidenced in Ge/Si experiments.

Details

Original languageEnglish
Article number554
Number of pages8
JournalNanoscale Research Letters
Volume12
Publication statusPublished - 29 Sept 2017
Peer-reviewedYes

External IDs

Scopus 85030640070
ORCID /0000-0002-4217-0951/work/142237426

Keywords

Keywords

  • Epitaxy, Silicon, Surface diffusion, Surface energy, Phase field, Epitaxy, Silicon, Surface diffusion, Surface energy, Phase-Field modeling, Self-Organization, Ge Islands, Nanostructures, Heteroepitaxy, Thin films