Optical phonon behaviors in ZnGeP2 single crystals from temperature dependent far-infrared reflectance spectra

Dispersion of Phonon Surface Polaritons in ZnGeP2: Anisotropy and Temperature Impacts

“…In the tetragonal ZnGeP 2 , B 2 (can be observed employing the radiation polarized parallel to the c -axis) and E (the radiation polarized normal to the c -axis) modes are infrared active. According to the data from [ 3 ], in the 200–500-cm −1 range, one can observe two B 2 and four E modes. Spectral analysis of the reflectance data has been performed employing factorized model for the dielectric permittivity in the following form: where ε ∞ is high-frequency dielectric permittivity and ν jl and γ jl ( ν jt and γ jt ) are the frequency and damping coefficient of the j th longitudinal (transversal) mode.…”

“…Due to the temperature shift of the phonon frequencies of ZnGeP 2 to the higher wave numbers [ 3 ], almost all branches of the 4 K dispersion lay above the corresponding branches at 300 K. The temperature-dependent phonon contributions in the dielectric permittivity, which are described by frequency, damping, and strength in frames of Lorentz model [ 3 ], affect dispersion of the surface polaritons in ZnGeP 2 .…”

“…As an input data for the calculations of the dispersion of phonon surface polariton (PSP), we used reflectance data of ZnGeP 2 from our study [ 3 ]. These spectra were measured at 300 K in the 200–500-cm −1 range, using a Bruker IFS 66v/s spectrometer with Hg lamp as the source of radiation with a resolution of 0.5 cm −1 , 256 scans per 20 s employing polarized radiation were collected in each experiment.…”

“…In the previous paper [ 3 ], we have reported on the lattice vibration behaviors of ZnGeP 2 single crystals derived from the far-infrared (FIR) reflectance spectra in the temperature range of 4–300 K. From [ 3 ], one can notice that optical phonon behaviors in ZnGeP 2 at low temperatures are similar to those in other diphosphides [ 4 , 5 ]. These results show that surface polaritons in ZnGeP 2 can be excited in the number of spectral ranges.…”

Quasiparticle effects on the linear and nonlinear susceptibility of ZnGeP2

“…13,14 The effects of optical phonon on the dielectric properties of ZnGeP 2 have also been studied using the far-infrared (FIR) reectance spectra at different temperature. 15 On the other hand, the electronic and optical properties of ZnGeP 2 are largely determined by quasiparticles excitations (most importantly the excitons). While their effects, to the best of our knowledge, have never been investigated.…”