Sm/GaAs(110) interface formation

Surface instabilities and kinetic constraints

T. Komeda, Steven G. Anderson, J. M. Seo, Matthias Schabel, J. H. Weaver

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Synchrotron radiation photoemission results for Sm/GaAs (110) interfaces formed and studied at 20 and 300 K show temperature dependencies that can be related to differences in surface growth structures and kinetic constraints. Submonolayer growth at 300 K produces two distinct ordered Sm chain configurations, as shown by scanning tunneling microscopy, and the photoemission results demonstrate that Sm atoms in these chains are divalent. These low-surface-density divalent configurations are precursors to surface disruption that, with additional Sm deposition, produce reacted clusters in which the Sm atoms are trivalent. Ultimately, Sm metal nucleation occurs on the reacted region and the overlayer thickens, with Ga and As atoms segregating to the surface region. For 20-K growth, the valence-band results show much slower conversion from divalent to trivalent Sm bonding, despite evidence that the amount of disruption is equivalent at 20 and 300 K. We attribute these differences, and those in the Ga and As core levels, to the freezing-in of an amorphous Sm-Ga-As mixture at 20 K. Hence, kinetic factors curtail atom rearrangements that occur readily at 300 K. Annealing of thin overlayers to 300 K removes kinetic constraints and produces Ga, As, and Sm bonding that is spectroscopically equivalent to that observed for 300-K growth. Sm/GaAs(110) interfaces formed by cluster assembly are shown to be unstable. Together, these results demonstrate that high-atom-density Sm contacts to GaAs are thermodynamically very unfavorable and that the instability generated by increasing the surface coverage provides the driving force for disruption.

Original languageEnglish (US)
Pages (from-to)1964-1971
Number of pages8
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume9
Issue number3
DOIs
StatePublished - 1991
Externally publishedYes

Fingerprint

Atoms
Kinetics
kinetics
atoms
Photoemission
photoelectric emission
Core levels
Scanning tunneling microscopy
Valence bands
configurations
Synchrotron radiation
Freezing
freezing
scanning tunneling microscopy
synchrotron radiation
Nucleation
assembly
Metals
gallium arsenide
nucleation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

Cite this

Sm/GaAs(110) interface formation : Surface instabilities and kinetic constraints. / Komeda, T.; Anderson, Steven G.; Seo, J. M.; Schabel, Matthias; Weaver, J. H.

In: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, Vol. 9, No. 3, 1991, p. 1964-1971.

Research output: Contribution to journalArticle

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