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 language | English (US) |
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Article number | 115206 |
Pages (from-to) | 1152061-1152067 |
Number of pages | 7 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 65 |
Issue number | 11 |
DOIs | |
State | Published - Mar 15 2002 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics