Photoelectron diffraction and photoelectron holography study of a Ge(111) high-temperature surface phase transition

T. T. Tran, S. Thevuthasan, Y. J. Kim, D. J. Friedman, A. P. Kaduwela, G. S. Herman, C. S. Fadley

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Further evidence for a reversible high-temperature surface-disordering phase transition at ∼1060 K on Ge(111) has been found using Ge 3p X-ray photoelectron diffraction (a short-range order probe of surface structure that is sensitive to the first 3-5 spheres of neighbors) and photoelectron holography (a recently suggested direct 3D imaging technique). Azimuthal diffraction data at takeoff angles of θ = 19° (including nearest-neighbor forward-scattering directions and yielding high surface sensitivity) and θ = 55° (for which second-nearest-neighbor forward-scattering directions and more bulk sensitivity are involved) show abrupt drops in intensity of ∼30%-40% over the temperature interval of 900-1200 K. Photoelectron holographic near-neighbor images at temperatures both below and above the transition region furthermore indicate an identical near-neighbor structure for all atoms present in ordered sites. These combined diffraction and holography data show that by 1200 K, the Ge(111) surface is covered by a completely disordered overlayer of 2.0-2.5 Ge monolayers in thickness. The rate of growth of this overlayer with increasing temperature is also in excellent agreement with recent medium-energy ion scattering results, although the thicknesses we find for the overlayer are 1.5-2.0 times larger. A more detailed analysis of the θ = 19° and the θ = 55° data also suggests the possible presence of a partially disordered interface between the liquid-like overlayer and the bulk, also of 2 Ge monolayers in thickness and consisting of laterally strained domains.

Original languageEnglish
Pages (from-to)270-284
Number of pages15
JournalSurface Science
Volume281
Issue number3
DOIs
Publication statusPublished - 1 Feb 1993
Externally publishedYes

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Holography
Photoelectrons
holography
photoelectrons
Diffraction
Phase transitions
Forward scattering
forward scattering
diffraction
Monolayers
Temperature
takeoff
Takeoff
ion scattering
imaging techniques
Surface structure
temperature
Scattering
Ions
intervals

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces

Cite this

Tran, T. T., Thevuthasan, S., Kim, Y. J., Friedman, D. J., Kaduwela, A. P., Herman, G. S., & Fadley, C. S. (1993). Photoelectron diffraction and photoelectron holography study of a Ge(111) high-temperature surface phase transition. Surface Science, 281(3), 270-284. https://doi.org/10.1016/0039-6028(93)90640-6

Photoelectron diffraction and photoelectron holography study of a Ge(111) high-temperature surface phase transition. / Tran, T. T.; Thevuthasan, S.; Kim, Y. J.; Friedman, D. J.; Kaduwela, A. P.; Herman, G. S.; Fadley, C. S.

In: Surface Science, Vol. 281, No. 3, 01.02.1993, p. 270-284.

Research output: Contribution to journalArticle

Tran, TT, Thevuthasan, S, Kim, YJ, Friedman, DJ, Kaduwela, AP, Herman, GS & Fadley, CS 1993, 'Photoelectron diffraction and photoelectron holography study of a Ge(111) high-temperature surface phase transition', Surface Science, vol. 281, no. 3, pp. 270-284. https://doi.org/10.1016/0039-6028(93)90640-6
Tran, T. T. ; Thevuthasan, S. ; Kim, Y. J. ; Friedman, D. J. ; Kaduwela, A. P. ; Herman, G. S. ; Fadley, C. S. / Photoelectron diffraction and photoelectron holography study of a Ge(111) high-temperature surface phase transition. In: Surface Science. 1993 ; Vol. 281, No. 3. pp. 270-284.
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