Resonant and Off-Resonant Phonon Properties of Wurtzite ZnS: Effect of Morphology on Fröhlich Coupling and Phonon Lifetime

We report the occurrence of morphology-induced variation in the phonon properties of a poly(vinylpyrrolidone)-capped ZnS semiconductor. ZnS micro- and nanostructures such as microparticles, nanoparticles, nanorods (NRs), and nanowires (NWs) were synthesized through a single-step hydrothermal method at low temperature. Structural, morphological, and compositional analyses were performed using powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectra (EDS), and high-resolution transmission electron micrographic techniques. Moreover, morphology of the prepared samples was confirmed from off-resonant Raman studies. A strong first and higher orders of longitudinal optical (LO) phonon and weak fundamental and higher orders of transverse optical features were seen from UV Raman scattering. The electron–phonon coupling as a function of morphological changes of the nanostructures was analyzed by studying the differences in LO phonon linewidths among the samples. The dominance...