Far infrared optical absorption studies of single crystal RuS_2-xSe_x

Tae dichalcogenides single crystal RuS_2-xSe_x have been studied by far-Infrared optical absorption measurements. We measured these single crystals in the spectra ranging from 100-700 cm^-1 over a temperature range from 80 to 300 K. Those vibration modes of these crystals are clearly shown temperature dependent behavior in far-infrared reflectance measurements. Also the temperature dependent vibration mode between these temperature varies smoothly with the Se composition value, that clearly showed in the absorption spectra. All these measured spectra indicate that the natures of phonons behavior are similar to RuS₂ and RuSe₂ in the limit of x values closing to 0 and 2. The main peaks of phonon modes of RuS_2-xSe_x are rich in around 207 to 416 cm^-1 and depend on intermediate compositions. All of these phonon modes are shown temperature dependent behavior. These phonon modes have 1-9 cm^-1 shift between temperature at 80-300 K in its reflectance far-infrared spectra. The phonon modes, carrier concentration, mobility, effective mass as well as their dielectric behavior of these crystals will go further study.