Bond-length relaxation in Si[sub 1[minus][ital x]]Ge[sub [ital x]] alloys
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)
We have measured and quantified the effect of alloy composition on the atomic bonding in relaxed molecular-beam-epitaxy-deposited crystalline Si[sub 1[minus][ital x]]Ge[sub [ital x]] alloys. X-ray-absorption fine structure (XAFS) and x-ray diffraction were used to examine how the atomic bonding in Si[sub 1[minus][ital x]]Ge[sub [ital x]] 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 [ital a][sup **] was used to quantify the linear dependence of the bond lengths on alloy composition and a value of [ital a][sup **]=0.63 was calculated from the measured bond lengths. An extensive XAFS error analysis was performed and the error in the topological rigidity parameter [ital a][sup **]=0.63[sub [minus]0.13][sup +0.08] was determined. This value of [ital a][sup **], which is notably different from 0 or 1, indicates that both the bond lengths and bond angles are distorted by changes in composition.
- DOE Contract Number:
- FG05-89ER45384
- OSTI ID:
- 7180641
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:20; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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