Far-infrared and Raman spectroscopy of Cd1−xMnxTe1−ySey: Phonon properties

Far-infrared reflectivity and Raman spectra of Cd1−xMnxTe1−ySey (x = 0.05, y = 0.11; x = 0.15, y = 0.1) single crystals were measured in the 40-300 cm−1 spectral range at 80 and 300 K temperatures. The analysis of the far-infrared spectra was carried out by a fitting procedure. We used a dielectric function that takes into account the existence of plasmon-LO phonon interaction. On that way the three optical mode frequencies (TO/LO pairs) at about 140/160, 170/190 and 205/210 cm−1 were obtained, depending on composition and temperature. In the Raman spectra we registered only the two first modes. We discussed these results in the frame of the model which we previously applied on Hg1−xMnxTe1−ySey. The agreement of the calculated phonon frequencies with experimentally determined ones is very good. We also present results of X-ray measurements.