Dielectric anisotropy and phonon modes of ordered indirect-gap Al_0.52In_0.48P studied by far-infrared ellipsometry

Authors

Tino Hofmann, University of Nebraska - LincolnFollow
V. Gottschalch, University of Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
Mathias Schubert, University of Nebraska - LincolnFollow

Date of this Version

2007

Comments

Published in Appl. Phys. Lett. 91, 121908 (2007). Copyright © 2007 American Institute of Physics. Used by permission.

Abstract

The infrared (100–600 cm⁻¹) optical properties of partially CuPt-type ordered Al_0.52In_0.48P deposited lattice matched on GaAs are studied by ellipsometry. The authors determine the ordinary and extraordinary dielectric functions and report on the evolution of the optical phonon mode frequencies of Al_0.52In_0.48P as a function of the degree of ordering. In addition to the InP- and AlP-like phonon modes, they observe two alloy-induced phonon modes which are anisotropic upon CuPt ordering. The observed modes are associated to vibrations with E and A₁ symmetries. The alloy-induced phonon modes are useful for classifying the degree of ordering in this indirect band gap alloy.