Near-forward Raman study of a phonon-polariton reinforcement regime in the Zn(Se,S) alloy

TL;DR

This study uses near-forward Raman scattering to explore phonon-polariton reinforcement in a Zn(Se,S) alloy near the Brillouin zone center, revealing strong mixed phonon-polariton modes at small scattering angles.

Contribution

It provides experimental evidence of phonon-polariton reinforcement in a zincblende alloy near the LO-regime using near-forward Raman scattering.

Findings

Observation of mixed phonon-polariton modes at small scattering angles.

Confirmation of phonon-polariton reinforcement near the LO-regime.

Use of ZnSe0.68S0.32 alloy with moderate refractive index dispersion.

Abstract

We investigate by near-forward Raman scattering a presumed reinforcement of the (A-C,B-C)-mixed phonon-polariton of a A1-xBxC zincblende alloy when entering its longitudinal optical (LO-)regime near the Brillouin zone centre {\Gamma}, as predicted within the formalism of the linear dielectric response. A choice system to address such issue is ZnSe0.68S0.32 due to the moderate dispersion of its refractive index in the visible range, a sine qua non condition to bring the phonon-polariton insight near {\Gamma}. The LO-regime is actually accessed by using the 633.0 nm laser excitation, testified by the strong emergence of the (Zn-Se,Zn-S)-mixed phonon-polariton at ultimately small scattering angles.