Molecular dynamics simulations of the growth of Ge on Si

SURFACE SCIENCE

卷:696

Article

Zhou, Ying¹  Lloyd, Adam¹  Smith, Roger^1,2  Lozovoy, Kirill A.²  Voitsekhovskii, Alexander V.²  Kokhanenko, Andrey P.² 

[1] Loughborough Univ, Sch Sci, Loughborough LE11 3TU, Leics, England

[2] Tomsk State Univ, Lab Nanoelect & Nanophoton, Lenin Ave 36, Tomsk 634050, Russia

关键词: Si-Ge quantum dots;    Molecular dynamics;    Pyramid formation;    Growth mechanisms;   

DOI  :  10.1016/j.susc.2020.121594

来源: Elsevier

【 摘 要 】

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 energies 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.

【 授权许可】

Free