Abstract
There are serious contradictions between extended x-ray-absorption fine structure (EXAFS) measurements of the Si-Ge and Ge-Ge bond lengths in both crystalline and amorphous silicon-germanium alloys, and in theoretical and simulation predictions. In particular, results from EXAFS experiments show that the Si-Ge and Ge-Ge bond lengths are independent of the alloy composition, indicating that there is no topological rigidity in the lattice. These EXAFS results on Si-Ge alloys are in sharp disagreement with all previous EXAFS results on III-V and II-VI semiconductor alloys. We discuss the implications of the EXAFS results regarding the local and global structure of the alloys. We also propose a structural model to serve as a focus for further experiments. In order to satisfy the overall floppiness of the network, we suggest that the Si-Ge samples may contain a large density of planar cracks, lined with hydrogen, and separated by ∼10 . Some measurements that could confirm (or discredit) this model are suggested.
Original language | English (US) |
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Pages (from-to) | 5172-5178 |
Number of pages | 7 |
Journal | Physical Review B |
Volume | 48 |
Issue number | 8 |
DOIs | |
State | Published - 1993 |
ASJC Scopus subject areas
- Condensed Matter Physics