Peculiarities of the Lattice Dynamics of Cubic Mercury Chalcogenides

The lattice dynamics of cubic mercury chalcogenides (HgTe, HgSe, β-HgS) was investigated by IR reflectivity, Raman scattering and inelastic neutron scattering measurements. The important role of two-phonon Raman scattering related to TA excitations was confirmed for HgSe and β-HgS and explained by the particular TA dispersion for mercury compounds. Analysis of the optical spectra taken for HgSe demonstrates that the resonant two-phonon difference process (widely accepted for HgTe, HgSe and the mixed crystals grown on the basis of these compounds) is not able to explain the present experimental data.