Optical constants, critical points, and phonon modes of GaAsN single layers

G. Leibiger, V. Gottschalch, A. Kasik, B. Rheinländer, J. Šik, M. Schubert

Research output: Contribution to journalArticlepeer-review


Spectroscopic ellipsometry (SE) is employed to study the optical properties of GaAs1-yNy [0% ≤ y ≤ 3.7%] single layers for photon energies from 0.75 eV to 4.5 eV and for wavenumbers from 100 cm-1 to 600 cm-1. We provide parametric model functions for the dielectric function spectra of GaAsN in both photon energy ranges. The model functions for photon energies from 0.75 eV to 4.5 eV excellently match dielectric functional data obtained from a numerical wavelength-by-wavelength inversion of the experimental data. Critical-point analysis of the ellipsometric data is performed in the spectral regions of the fundamental band gap and the critical points E1 and E11. The band-gap energy is red shifted whereas the E1 and E11 transition energies are blue shifted with increasing y. For y ≤ 1.65% the observed blue shift of the E1 energy is well explained by the sum of the effects of biaxial (001) strain and alloying. The GaAsN layers show two-mode behaviour in the infrared spectral range (100 cm-1 to 600 cm-1). We detect the transverse GaAs- and GaN- sublattice modes at wavenumbers of about 267 cm-1 and 470 cm-1, respectively. The polar strength of the GaN TO mode increases linearly with y. This effect can be used to monitor the nitrogen composition in GaAsN layers.

Original languageEnglish (US)
Pages (from-to)G6.35.1-G6.35.6
JournalMaterials Research Society Symposium - Proceedings
StatePublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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