  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.
