Bond-length relaxation in Si1-xGex alloys

D. B. Aldrich, Robert Nemanich, D. E. Sayers

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

We have measured and quantified the effect of alloy composition on the atomic bonding in relaxed molecular-beam-epitaxy-deposited crystalline Si1-xGex alloys. X-ray-absorption fine structure (XAFS) and x-ray diffraction were used to examine how the atomic bonding in Si1-xGex is affected by changes in alloy composition. In this study, the Ge-Ge and Ge-Si bond lengths were measured using XAFS and compared with the conflicting results of existing analytical models and previous XAFS studies. The measured Ge-Ge and Ge-Si bond lengths were found to be in good agreement with the analytical models, which predict that the Ge-Ge, Ge-Si, and Si-Si bonds maintain distinctly different lengths which change linearly with alloy composition. The topological rigidity parameter a** was used to quantify the linear dependence of the bond lengths on alloy composition and a value of a**=0.63 was calculated from the measured bond lengths. An extensive XAFS error analysis was performed and the error in the topological rigidity parameter a**=0.63-0.13+0.08 was determined. This value of a**, which is notably different from 0 or 1, indicates that both the bond lengths and bond angles are distorted by changes in composition.

Original languageEnglish (US)
Pages (from-to)15026-15033
Number of pages8
JournalPhysical Review B
Volume50
Issue number20
DOIs
StatePublished - 1994
Externally publishedYes

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Bond length
X ray absorption
fine structure
Chemical analysis
rigidity
Rigidity
Analytical models
x rays
error analysis
Molecular beam epitaxy
Error analysis
x ray diffraction
molecular beam epitaxy
Diffraction
Crystalline materials
X rays

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Bond-length relaxation in Si1-xGex alloys. / Aldrich, D. B.; Nemanich, Robert; Sayers, D. E.

In: Physical Review B, Vol. 50, No. 20, 1994, p. 15026-15033.

Research output: Contribution to journalArticle

Aldrich, D. B. ; Nemanich, Robert ; Sayers, D. E. / Bond-length relaxation in Si1-xGex alloys. In: Physical Review B. 1994 ; Vol. 50, No. 20. pp. 15026-15033.
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