Disorder and compositional dependences in Urbach-Martienssen tails in amorphous (GeTe)x(Sb2Te3)1-x alloys

This work focuses on the compositional dependences in parameters that govern the optical properties of (GeTe)_x(Sb₂Te₃)_1−x amorphous alloys in the wide spectral range from above the phonons and to the inter-band electronic transitions. We studied the absorption edge fluctuations that are linked to the variations of the bandgap E_g, the width of Urbach-Martienssen tails E_U, the Tauc parameter B^1/2, and average halfwidth <FWHM> of Raman bands in amorphous (GeTe)_x(Sb₂Te₃)_1−x alloys at various temperatures. Obtained results reveal the compositional trends in the influence of the disordering on the absorption processes in studied alloys.

Spectroscopy of the Surface Polaritons in the CdXZn(1-X)P2 Solid Solutions

Here we report on the analysis of the effect of the doping of CdP₂ single crystals by ZnP₂ nanoclusters on the dispersion of the surface polaritons (SP). The ATR spectroscopic technique has been applied to excite the SP in the Cd_XZn_(1-X)P₂ system. Analysis of the obtained spectra has shown that the doping of CdP₂ single crystals by ZnP₂ nanoclusters result in the position and the width of the dispersion branches of the SP. This effect is more pronounced in the low frequency dispersion branches. These SP branches are originated from phonons which correspond to the motion of the cation sublattice.

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

Zinc germanium diphosphide (ZnGeP2) is an attractive and promising functional material for different devices of the nano- and optoelectronics. In this paper, dispersion of phonon surface polaritons (PSPs) in ZnGeP2 has been studied in the 200-500-cm(-1) spectral range at 4 and 300 K. Dispersion of "real" and "virtual" PSPs were calculated for C-axis being normal and parallel to the surface. Anisotropy in ZnGeP2 leads to the different numbers of PSP dispersion branches for different orientations of the sample. The temperature-dependent phonon contributions in the dielectric permittivity shift dispersion of the surface polaritons in ZnGeP2 to the higher wavenumbers at 4 K. We have shown that experimental dispersion of PSP is in agreement with theory.