Accelerated molecular dynamics study of the GaAs(001)β2(2×4)/ c(2×8) surface

Yangzheng Lin, Kristen Ann Fichthorn

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We develop an accelerated molecular dynamics method that has several advantages over conventional rare-event methods. We apply our method using a semiempirical Tersoff-Abell potential to understand the disordered structure of the GaAs(001)β2(2×4) surface at various temperatures. Our simulations indicate that the self-reconstruction of this surface is mediated by As-row-dimer and As-trench-dimer shifting events that typically occur over microsecond-millisecond times at temperatures of interest and that trench-dimer shifting occurs more rapidly than row-dimer shifting. Our calculations indicate that the equilibrium surface consists of an approximately equal mixture of β2(2×4) and c(2×8) domains, in agreement with an experimental scanning-tunneling microscopy study. Due to strain along the [11̄0] direction, there is a tendency for the surface to form long runs of in-phase As-row- and As-trench dimers. There are weak correlations between As-row-dimer pairs along the [110] direction such that the free energy of the c(2×8) surface is slightly lower than that of the β2(2×4) surface. This finding is also in agreement with the experiment and indicates the dynamical nature of this important substrate for thin-film growth.

Original languageEnglish (US)
Article number165303
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume86
Issue number16
DOIs
StatePublished - Oct 2 2012

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Dimers
Molecular dynamics
dimers
molecular dynamics
Scanning tunneling microscopy
Film growth
Free energy
gallium arsenide
scanning tunneling microscopy
tendencies
free energy
Thin films
Temperature
temperature
Substrates
thin films
simulation
Experiments
Direction compound

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

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abstract = "We develop an accelerated molecular dynamics method that has several advantages over conventional rare-event methods. We apply our method using a semiempirical Tersoff-Abell potential to understand the disordered structure of the GaAs(001)β2(2×4) surface at various temperatures. Our simulations indicate that the self-reconstruction of this surface is mediated by As-row-dimer and As-trench-dimer shifting events that typically occur over microsecond-millisecond times at temperatures of interest and that trench-dimer shifting occurs more rapidly than row-dimer shifting. Our calculations indicate that the equilibrium surface consists of an approximately equal mixture of β2(2×4) and c(2×8) domains, in agreement with an experimental scanning-tunneling microscopy study. Due to strain along the [11̄0] direction, there is a tendency for the surface to form long runs of in-phase As-row- and As-trench dimers. There are weak correlations between As-row-dimer pairs along the [110] direction such that the free energy of the c(2×8) surface is slightly lower than that of the β2(2×4) surface. This finding is also in agreement with the experiment and indicates the dynamical nature of this important substrate for thin-film growth.",
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Accelerated molecular dynamics study of the GaAs(001)β2(2×4)/ c(2×8) surface. / Lin, Yangzheng; Fichthorn, Kristen Ann.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 86, No. 16, 165303, 02.10.2012.

Research output: Contribution to journalArticle

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