Using a micro-Raman setup, in-plane Raman scattering was performed on short-period (001)-Si/Ge superlattices, and the complete phonon spectrum (longitudinal and transverse, optical and acoustic modes) could be studied. In the relevant wave-vector range, the in-plane dispersion was found to affect the frequencies of folded-acoustic modes, while being negligible for confined optical modes. The comparison with theoretical spectra, calculated by means of first-principles interatomic force constants, shows that the observed deviations of ''unfolded'' confined optical modes from the bulk dispersions can be attributed to interface roughness and is well described by a simple alloy layer model (2-3 intermixed SiGe atomic layers at interfaces).
In-plane Raman scattering of (001)-Si/Ge superlattices: Theory and experiment / Schorer, R.; Abstreiter, G.; De Gironcoli, S.; Molinari, E.; Kibbel, H.; Presting, H.. - In: PHYSICAL REVIEW. B, CONDENSED MATTER. - ISSN 0163-1829. - 49:8(1994), pp. 5406-5414. [10.1103/PhysRevB.49.5406]
In-plane Raman scattering of (001)-Si/Ge superlattices: Theory and experiment
De Gironcoli, S.;
1994-01-01
Abstract
Using a micro-Raman setup, in-plane Raman scattering was performed on short-period (001)-Si/Ge superlattices, and the complete phonon spectrum (longitudinal and transverse, optical and acoustic modes) could be studied. In the relevant wave-vector range, the in-plane dispersion was found to affect the frequencies of folded-acoustic modes, while being negligible for confined optical modes. The comparison with theoretical spectra, calculated by means of first-principles interatomic force constants, shows that the observed deviations of ''unfolded'' confined optical modes from the bulk dispersions can be attributed to interface roughness and is well described by a simple alloy layer model (2-3 intermixed SiGe atomic layers at interfaces).File | Dimensione | Formato | |
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