Low-temperature growth on Si(111) substrates

Journal Article · Sat Oct 15 04:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.10932· OSTI ID:7180467

Biswas, R ^[1]; Roos, K ^[2]; Tringides, M C ^[3]

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1. Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States) Microelectronics Research Center, Iowa State University, Ames, Iowa 50011 (United States) Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)
2. Department of Physics, Bradley University, Peoria, Illinois 61625 (United States)
3. Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States) Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)

Low-temperature ([ital T][lt]150 K) reflection high-energy electron-diffraction (RHEED) oscillations during the growth of ultrathin films suggest the presence of nonzero adatom mobility. In most systems thermal diffusion cannot account for the observed oscillations, and the origin of the oscillations is still unclear. Experiments on Ag/Si(111) at 150 K demonstrate the absence of thermal diffusion based on the scaling of the RHEED intensity at different flux rates (i.e., the diffracted intensity is only a function of the total deposited amount independent of the flux rate). We have performed molecular-dynamics simulations to understand possible low-temperature mechanisms responsible for the oscillations. Classical two- and three-body Si potentials were used together with an adatom mass that is 3.84 times the Si mass to account for the Ag/Si mass ratio. Results indicate that the landing site of the adatom is important in predicting the subsequent lateral motion of the adatom. A majority (about 75%) of the deposited atoms adsorb within a lattice spacing of the landing site. However, a fraction (25%) of the deposited atoms eventually adsorb a few lattice spacings away from the landing site before equilibration to the substrate, but it is not clear if this is sufficient to account for the oscillations. The energy transfer to the substrate is much less efficient than in fcc/fcc systems, because of the stiffness of the Si-Si potentials.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 7180467
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:15; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
DIFFRACTION
ELECTRON DIFFRACTION
ELEMENTS
EPITAXY
MATHEMATICAL MODELS
METALS
MOBILITY
MOLECULAR MODELS
NUCLEATION
OSCILLATIONS
POTENTIALS
SCATTERING
SEMIMETALS
SEPARATION PROCESSES
SILICON
SILVER
SORPTION
SORPTIVE PROPERTIES
SURFACE POTENTIAL
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TRANSITION ELEMENTS