https://doi.org/10.1007/s100510170015
First-order Raman spectra from In1-x-yGaxAlyAs epitaxial layers grown on InP substrates
1
Gazi University, Faculty of Arts and Sciences, Department
of Physics, 06500, Ankara, Turkey
2
Department of Physics,
University of Essex, Colchester, Essex, CO4 3SQ, UK
Corresponding author: a mahir@quark.fef.gazi.edu.tr
Received:
6
January
2001
Revised:
16
July
2001
Published online: 15 November 2001
We report on Raman scattering by longitudinal optical
phonons in InGaxAlyAs quaternary alloys
lattice-matched to InP(with
). The quaternary alloy
samples were grown as epilayers on InP(001) substrates by molecular
beam epitaxy. The Raman phonon spectra show a three-mode behaviour
involving the InAs-, GaAs- and AlAs-like longitudinal optic phonon
modes. The frequencies of GaAs- and AlAs-like modes vary linearly with
the concentration of the Ga (or Al) while the position of the
InAs-like phonon remains nearly constant. We show that the ratio of
intensities of the modes is proportional to the corresponding ratio of
their compositions. Disorder activated modes in the acoustic and
optic regions due to the disorder in atomic arrangements of group III
elements have also been observed. The mode frequencies have been
modeled using the extended form of the Random Cell Iso-Displacement
model (RCI), which provides a good description of the experimental
results.
PACS: 78.30.Fs – III-V and II-VI semiconductors
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001