Near-band-gap optical functions spectra and band-gap energies of GaNAs/GaAs superlattice heterostructures measured by spectroscopic ellipsometry

J. Šik, M. Schubert, G. Leibiger, V. Gottschalch, G. Kirpal, J. Humlíček

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

The optical properties of GaAs/GaNxAS1-x. superlattice structures grown by metal-organic vapor-phase epitaxy are studied by variable angle-of-incidence spectroscopic ellipsometry for photon energies from 0.75 to 1.55 eV. We employ Adachi's critical-point composite model, and we report the direct-band-gap energy E0 and the complex index of refraction of the GaNxAs1-x sublayers for x≤3.3% from analysis of the ellipsometry data. We observe a strong redshift of E0 with increase in x, and a strong decrease of the E0 transition amplitude. The E0 values obtained for the superlattice structures are in good agreement with photoluminescence results, and also with previous reports from single epilayers. Structure, composition, layer thickness, and parallel and perpendicular lattice mismatch of the samples are studied by transmission electron microscopy and high-resolution x-ray diffraction investigations.

Original languageEnglish (US)
Pages (from-to)2859-2861
Number of pages3
JournalApplied Physics Letters
Volume76
Issue number20
DOIs
StatePublished - May 15 2000

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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