Al4SiC4 vibrational properties: Density Functional Theory calculations compared to Raman and Infrared spectroscopy measurements

TL;DR

This study combines experimental Raman and IR spectroscopy with Density Functional Theory calculations to analyze the vibrational properties of Al4SiC4, a wide band gap semiconductor, achieving good agreement and detailed mode assignments.

Contribution

It provides the first comprehensive experimental vibrational analysis of Al4SiC4 and revisits DFT calculations for improved IR mode predictions and symmetry assignments.

Findings

Good agreement between experimental and theoretical Raman modes

Revised DFT calculations show decreased LO-TO splitting variation

Most IR modes assigned through comparison with Raman spectra

Abstract

Al4SiC4 is a wide band gap semiconductor with numerous potential technological applications. We report here the first thorough experimental Raman and Infrared (IR) investigation of vibrational properties of Al4SiC4 single crystals grown by high temperature solution growth method. The experimental results are compared with the full theoretical analysis of vibrational properties based on Density Functional Theory calculations that are revisited here. We have obtained a good agreement between the experimental and calculated Raman phonon modes and this allowed the symmetry assignment of all the measured Raman modes. We have revisited the DFT calculation of the IR active phonon modes and our results for LO-TO splitting indicate a substantial decrease of the variation of omega(LO-TO) compared with the previous reported calculation. Moreover, most of the IR modes have been symmetry assigned from the comparison of the experimental IR spectra with the corresponding Raman spectra and the Al4SiC4 calculated phonon modes.