Theoretical investigation of lattice dynamics, dielectric properties, infrared reflectivity and Raman intensity spectra of Nowotny chimney-ladder semiconducting silicide Ru2Si3.

Abstract Semiconducting silicides are highly promising materials for applications in thermoelectric, photovoltaic and optoelectronic devices. Here, using ab-initio density functional theory, the lattice dynamics, dielectric properties, Infrared (IR) refletivity and Raman intensity spectra of Nowotny chimney-ladder semiconducting silicide Ru 2 Si 3 are investigated. The zone-center phonon mode frequencies are found to be in the range 80–510 cm−1. The Born effective charge tensor, oscillator strength and Infrared activity is found to largest for the mode with frequency 422 cm−1 which is primarily contributed by displacements of Si atoms. The largest Raman activity is obtained for mode with frequency 479 cm−1 which is also dominated by vibrations of Si atoms. Modified Becke-Johnson (MBJ) exchange potential is used to compute the band gap of Ru 2 Si 3 which improves the band gap by ∼8% as compared to that obtained using LDA. The computed Infrared reflectivity and Raman intensity spectra are expected to provide benchmark first-principles theoertical results for comparison with the experiments. Highlights • Ab-initio calculations of lattice dynamics and dielectric properties of Ru 2 Si 3. • Ab-initio calculations of Infrared reflectivity and Raman spectra of Ru 2 Si 3. • Significant Raman intensities are obtained for modes 91, 231 and ∼479 cm−1. • Born effective charges and IR activity are found to be largest for mode 422 cm−1. [ABSTRACT FROM AUTHOR]