Investigation of the vibrational spectrum of SbSeI crystals in harmonic and in the anharmonic approximations

Abstract

The reflectivity spectrum RðoÞ of SbSeI crystals was experimentally studied in the spectral range of 102300 cm À1 over a wide range of temperatures (10-297 K) with light polarization Ekc and E ? c . The spectra of optical constants and optical functions were calculated using the Kramers-Kronig and optical parameter fitting methods. The dependence of the frequencies o T and o L of the low-frequency B 1u mode (for Ekc) on temperature was obtained from the experiment. From spectra e ll ðoÞ and Imðe À1 ÞðoÞ the frequencies o L and o T of B 1u normal modes were found at temperatures 10-297 K. The frequencies of normal modes and amplitudes of normal coordinates were calculated by diagonalization of the dynamical matrix in harmonic approximation. The properties of the low-frequency B 1u mode are explained in anharmonic approximation by employing the average potential energy function V ðzÞ. The latter is strongly anharmonic and thus causes the frequency of this mode to show a quite strong temperature dependence. The interaction between phonons creates the anharmonicity of low-frequency B 1u vibrational mode. r

INVESTIGATION OF ELECTRONIC PROPERTIES OF SbSeI UNDER HIGH PRESSURE BY FIRST PRINCIPLES CALCULATIONS

“…They studied their photoconducting properties [8]. Many studies have been carried out on the electrical conductivity [13], electronic, thermoelectric [11], microelectronic, and optoelectronic [1] properties, reflectivity and vibrational spectrum [18] of SbSeI. SbSel's single crystals were grown using the vapor phase technique and the reverse current -voltage (I -V) characteristics of the system were analyzed in the 273 to 363 K temperature range [10].…”