Interband transitions and phonon modes in BxGa1−xAs (0 < x < 0.03) and GaNyAs1−y (0 < y < 0.037): A comparison

Gunnar Leibiger, Volker Gottschalch, Volker Riede, Mathias Schubert, James N. Hilfiker, Thomas E. Tiwald

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

We report on the experimental observation of direct interband-critical-point transitions and phonon modes in BxGa1−xAs alloys (0 < x < 0.03) and their evolution with increasing boron concentration using spectroscopic ellipsometry and Raman scattering. Our results are compared to the corresponding values in the GaNyAs1−y (0 < y < 0.037) material system. For BxGa1−xAs, we obtain only a small bowing coefficient of the Eg(x) dependence in contrast to the giant redshift of the GaNyAs1−y band-gap energy with y. The higher lying interband-transition energies of BxGa1−xAs (E1, E1 + Δ1, E0′, E2, and E1′) are slightly redshifted with increasing boron concentration. A similar behavior is found for the critical points E0′, E2, and E1′ in GaNyAs1−y. In BxGa1−xAs, we observe, as in GaNyAs1−y, a two-mode phonon behavior using Raman scattering. However, from infrared-ellipsometry or -transmission experiments, we can estimate that the oscillator strength or polarity of the BAs-like phonon is at least one order of magnitude smaller than the oscillator strength of the GaN-like phonon measured at a GaNyAs1−y layer with comparable thickness and composition. All results will be explained using a simple model that takes into account the different nature of the chemical bonds in both alloy types.

Original languageEnglish (US)
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume67
Issue number19
DOIs
StatePublished - May 22 2003

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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