Phonon mode behavior in strained wurtzite AlN/GaN superlattices

V. Darakchieva, E. Valcheva, P. P. Paskov, M. Schubert, T. Paskova, B. Monemar, H. Amano, I. Akasaki

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We have studied phonons in AlN/GaN superlattices with different periods but a constant well-to-barrier ratio using a combination of infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The strain evolution in the superlattice structures is assessed by high-resolution x-ray diffraction and reciprocal space mapping. We have identified E 1(TO), A 1(LO) and E 2 localized, and E 1(LO) and A 1(TO) delocalized superlattice modes. The dependencies of their frequencies on in-plane strain are analyzed and discussed, and the strain-free frequencies of the superlattice modes are estimated. A good agreement between theory and experiment is found in the case of GaN localized modes, while large deviations between theoretically estimated and experimentally determined frequency shifts are observed for the AlN localized modes. The delocalization effect on the A 1(TO) and E 1(LO) phonons, as well as the free-carrier effect on the E 1(LO) phonon are also discussed.

Original languageEnglish (US)
Article number115329
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number11
Publication statusPublished - Mar 15 2005


ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Darakchieva, V., Valcheva, E., Paskov, P. P., Schubert, M., Paskova, T., Monemar, B., ... Akasaki, I. (2005). Phonon mode behavior in strained wurtzite AlN/GaN superlattices. Physical Review B - Condensed Matter and Materials Physics, 71(11), [115329].