Optical phonons in hexagonal AlxInyGa1-x-yN (y ≈ 0.12)

A. Kasic, M. Schubert, J. Off, F. Scholz, S. Einfeldt, D. Hommel

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

We report on first studies of the phonon mode properties of hexagonal AlxInyGa1-x-yN films. The 200-330 nm thick quaternary films (0 ≤ x ≤ 0.40, y ≈ 0.12), grown by MOCVD on 6H-SiC substrates, are pseudomorphically strained to the GaN buffer layers. We observe and differentiate the influence of strain and alloying on the frequency of the GaN-like E1(TO) phonon mode of AlxInyGa1-x-yN using infrared spectroscopic ellipsometry. Assuming the effective electron mass value of GaN, the free-electron concentrations are estimated from the A1-LO-phonon-plasmon coupled mode frequencies and increase by about two orders of magnitude in going from x = 0 to x = 0.40. We further obtain the composition dependence of the polarity for the AlN-like phonon mode with E1 symmetry. A possibly disorder-induced absorption band occurs above the GaN-like E1(TO) mode.

Original languageEnglish (US)
Pages (from-to)970-974
Number of pages5
JournalPhysica Status Solidi (B) Basic Research
Volume234
Issue number3
DOIs
StatePublished - Dec 1 2002

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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