Optical phonon modes and interband transitions in cubic (formula presented) films

A. Kasic, M. Schubert, T. Frey, U. Köhler, D. J. As, C. M. Herzinger

Research output: Contribution to journalArticle

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Abstract

We present a comprehensive study of the phonon mode behavior and the optical interband transitions of cubic (formula presented) films (formula presented) using spectroscopic ellipsometry from the midinfrared to the vacuum-ultraviolet spectral range (0.05-8.5 eV). The (formula presented) layers were grown by radio-frequency plasma-assisted molecular-beam epitaxy and possess free-electron concentrations in the range of (formula presented) A two-mode behavior for the transverse-optical phonon of (formula presented) is observed, which is consistent with theoretical predictions. Due to the high free-electron concentration, the observed (formula presented) fundamental band-gap energy (formula presented) is subject to a strong Burstein-Moss shift and band-gap renormalization. We quantify the amount of both band-gap shifting mechanisms, and provide an estimate for the composition dependence of the (formula presented) band-gap energy (formula presented) which depends approximately linearly on the alloy composition with (formula presented) at room temperature and for carrier-depleted material. For cubic GaN, the L-point interband transition (formula presented) shifts to lower energies with increasing free-electron concentration, whereas the interband transition (formula presented) remains unshifted. Increasing Al content induces a blueshift (redshift) of the (formula presented) for (formula presented) Due to strong broadening effects, both transitions cannot be differentiated anymore for (formula presented).

Original languageEnglish (US)
Pages (from-to)1-13
Number of pages13
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number18
DOIs
StatePublished - Jan 1 2002

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Energy gap
Electrons
Optical transitions
Spectroscopic ellipsometry
Electron transitions
Chemical analysis
Molecular beam epitaxy
free electrons
Vacuum
Plasmas
Bryophytes
Temperature
shift
transition points
optical transition
ellipsometry
radio frequencies
molecular beam epitaxy
vacuum

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Optical phonon modes and interband transitions in cubic (formula presented) films. / Kasic, A.; Schubert, M.; Frey, T.; Köhler, U.; As, D. J.; Herzinger, C. M.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 65, No. 18, 01.01.2002, p. 1-13.

Research output: Contribution to journalArticle

Kasic, A. ; Schubert, M. ; Frey, T. ; Köhler, U. ; As, D. J. ; Herzinger, C. M. / Optical phonon modes and interband transitions in cubic (formula presented) films. In: Physical Review B - Condensed Matter and Materials Physics. 2002 ; Vol. 65, No. 18. pp. 1-13.
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