Abstract
We performed a theoretical study of the microscopic arrangement of the C atoms in Si 1×x-yGe xC y alloys using the Sankey local-orbital density-functional formalism. Our first-principles calculations show that in the dilute limit, the lattice constant in Si 1-yC y alloys decreases much more (by about 2/3) with concentration than predicted by Vegard's law. We show that this result is consistent with Raman and infrared experiments and with previous empirical calculations. As the C concentration increases, the interactions between the C atoms become important: Interstitial C becomes more abundant and increases the lattice constant, and the substitutional C atoms array under appropriate growth conditions. The effect of this ordering on the lattice constant is small, but it can be seen in the Raman spectra of layer-by-layer grown samples.
Original language | English (US) |
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Title of host publication | Materials Research Society Symposium - Proceedings |
Publisher | MRS |
Pages | 443-448 |
Number of pages | 6 |
Volume | 469 |
State | Published - 1997 |
Externally published | Yes |
Event | Proceedings of the 1997 MRS Spring Symposium - San Francisco, CA, USA Duration: Apr 1 1997 → Apr 4 1997 |
Other
Other | Proceedings of the 1997 MRS Spring Symposium |
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City | San Francisco, CA, USA |
Period | 4/1/97 → 4/4/97 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials