Coherent-potential approximation for vibrations in Ga1—xInxSb and Ga1—xInxAs mixed crystals
✍ Scribed by P. Kleinert
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- English
- Weight
- 563 KB
- Volume
- 114
- Category
- Article
- ISSN
- 0370-1972
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✦ Synopsis
Abstract
The vibrational properties of the mixed crystals Ga~1—x~In~x~As and Ga~1—x~In~x~Sb are investigated using the coherent‐potential approximation (CPA). These III—V systems switch from one‐mode to two‐mode behaviour as the composition is changed. Results are obtained for a one‐dimensional model including self‐consistently mass defects and force constant changes. The calculated density of states and the dielectric susceptibility are compared with results of the mass CPA. In addition, a three‐dimensional CPA Bethe lattice treatment is carried out to calculate the optical properties of these disordered systems showing mixed‐mode behaviour. The force‐constant change is included by a virtual‐crystal interpolation. The theory explains the mode switching behaviour and agrees fairly well with experimental peak positions and line shapes of the response function.