Effective electron mass and phonon modes in n-type hexagonal InN

A. Kasic, M. Schubert, Y. Saito, Y. Nanishi, G. Wagner

Research output: Contribution to journalArticle

187 Scopus citations

Abstract

Infrared spectroscopic ellipsometry and micro-Raman scattering are used to study vibrational and electronic properties of high-quality hexagonal InN. The 0.22-μm-thick highly n-conductive InN film was grown on c-plane sapphire by radio-frequency molecular-beam epitaxy. Combining our results from the ellipsometry data analysis with Hall-effect measurements, the isotropically averaged effective electron mass in InN is determined as 0.14mO. The resonantly excited zone center E1(TO) phonon mode is observed at 477 cm-1 in the ellipsometry spectra. Despite the high electron concentration in the film, a strong Raman mode occurs in the spectral range of the unscreened A1(LO) phonon. Because an extended carrier-depleted region at the sample surface can be excluded from the ellipsometry-model analysis, we assign this mode to the lower branch of the large-wave-vector LO-phonon-plasmon coupled modes arising from nonconserving wave-vector scattering processes. The spectral position of this mode at 590 cm-1 constitutes a lower limit for the unscreened A1(LO) phonon frequency.

Original languageEnglish (US)
Article number115206
Pages (from-to)1152061-1152067
Number of pages7
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number11
DOIs
StatePublished - Mar 15 2002

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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