Isotropic dielectric functions of highly disordered AlxGa1-xInP (0 ≤ x ≤ 1) lattice matched to GaAs

M. Schubert, J. A. Woollam, G. Leibiger, B. Rheinländer, I. Pietzonka, T. Saß, V. Gottschalch

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56 Scopus citations

Abstract

Determination of the complex dielectric function and the critical-point energies of (AlxGa1-x)0.51In0.49P, over the full range of composition x and for photon energies E from 0.75 to 5 eV is reported from variable angle of incidence spectroscopic ellipsometry. Native-oxide effects on the (AlxGa1-x)0.51In0.49P optical functions are removed numerically. The highly disordered state of the metalorganic vapor-phase epitaxy grown samples is analyzed by transmission electron microscopy. Optical anisotropy investigations revealed that the order-induced optical birefringence is negligible throughout. The augmentation of A. D. Rakić and M. L. Majewski [J. Appl. Phys. 80, 5909 (1996)] to Adachi's critical-point model, i.e., consideration of Gaussian-like broadening function instead of Lorentzian broadening, is used for calculation of the isotropic (AlxGa1-x)0.51In0.49P dielectric function ∈. The optical functions spectra consistently match the experimental data, whereas previously reported model dielectric functions fail to reproduce the correct absorption behavior of the quaternary, especially near the fundamental band-to-band transition. The results are compared to those presented previously, and influence of spontaneous chemical ordering is discussed.

Original languageEnglish (US)
Pages (from-to)2025-2033
Number of pages9
JournalJournal of Applied Physics
Volume86
Issue number4
DOIs
StatePublished - Aug 15 1999

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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