Plasmon-phonon rsonance in semiconducting samarium monosulphide films

Optical spectra of semiconducting samarium monosulfide (Π-SmS) were investigated. Reflection band at 300 K from a polycrystalline film Π-SmS of 3.4 μm thick with ∼ 1019 cm-3 conduction electron concentration in 14-23 μm spectral region is observed. Sharp reflection structure at hω=0.08-0.06 eV is due to contribution of longitudinal optical phonon ineraction with plasmons. It is shown that experimental data agree well with a theoretical model of plasmon-phonon resonance. Agreement of experimental data and theory was performed, numerical values of some parameters characterizing the process were determined, namely: permittivity, frequences of optical branch of lattice oscillation spectrum, damping parameters