Phonon-polaritons in Zn1<b>−</b> <i>x</i>Mg<i>x</i>Te (x≤ 0.09): A Raman scattering study

Abstract

Phonon-polaritons (PPs) are phonon–photon coupled modes. Using near-forward Raman scattering, the PP of the cubic Zn1−xMgxTe (x≤ 0.09) semiconductor alloy could be measured. While the PP-coupling hardly develops in pure ZnTe, minor Mg-alloying suffices to stabilize a long-lifetime PP strongly bound to the lattice, i.e., with a pronounced phonon character, and yet a fast one originating from the highly dispersive photon-like bottleneck of the PP-dispersion. By combining the advantages of a phonon and a photon, the long-lifetime PP generated by minor Mg-alloying of ZnTe marks an improvement over the PP of pristine ZnTe, which, from the Raman cross section calculation, can only achieve a balanced compromise between the two kinds of advantages, intensity and speed. The discussion of the PP-related lattice dynamics of Zn1−xMgxTe (x≤ 0.09) is grounded in a preliminary study of the lattice macro- and microstructure using x-ray diffraction and solid-state nuclear magnetic resonance, respectively, and further relies on ab initio calculations of the native phonon modes behind the PP in the Mg-dilute limit of Zn1−xMgxTe (x∼ 0), considering various Mg isotopes.