2134/11882094.v1
Ying Zhou
Ying
Zhou
Adam Lloyd
Adam
Lloyd
Roger Smith
Roger
Smith
Kirill A. Lozovoy
Kirill A.
Lozovoy
Alexander V. Voitsekhovskii
Alexander V.
Voitsekhovskii
Andrey P. Kokhanenko
Andrey P.
Kokhanenko
Molecular dynamics simulations of the growth of Ge on Si
Loughborough University
2020
Si-Ge quantum dots
Molecular dynamics
Pyramid formation
Growth mechanisms
Quantum Mechanics
Condensed Matter Physics
2020-02-25 09:38:40
Journal contribution
https://repository.lboro.ac.uk/articles/journal_contribution/Molecular_dynamics_simulations_of_the_growth_of_Ge_on_Si/11882094
<div>The initial stages of the growth of germanium on the dimer reconstructed Si(100) surface is modelled using molecular dynamics (MD). Pyramidal island structures are observed to form despite MD being carried out at a deposition rate faster than experiment. By an examination of transitions that can occur from intermediate structures that form in the MD simulations, growth mechanisms can be identified. The initial wetting occurs as a result of Ge atoms diffusing into the trenches between the dimer rows. This results in Ge-Ge or Ge-Si dimer chains growing in rows perpendicular to the original Si-Si dimer rows on the surface. It is shown how strained Ge pyramids with square bases can form by diffusing atoms joining together adjacent dimer rows. From these initial square-based structures, complex concerted motions are observed in which atoms in lower layers ‘climb up’ to higher layers. Similar structures grown in the pure Si case exhibit much higher energy barriers for the ‘climbing up’ process indicating that the effect of strain is to reduce the energy barriers for pyramid formation. In addition to the investigation of atomistic growth processes, surface energy effects are also examined, which show that a germanium-covered Si(100) surface containing shallow-angled pyramids is energetically more favourable than that grown as a flat monolayer.</div>