Polarized Ultraviolet Raman Spectroscopy of Β-Si3N4
R Vogelgesang, M Grimsditch, Jay S. Wallace
We have studied single crystals of Β-Si3N4 with polarization-resolved Raman spectroscopy in order to unambiguously obtain the symmetry character of zone center optical phonon modes. By applying ultraviolet excitation radiation, approaching resonance condition, we have overcome the usual difficulties with overwhelming fluorescence obscuring Raman spectra of Β-Si3N4 in the visible. Superior extinction ratios have been achieved and the application of group theory allows us to assign ten out of eleven Raman-active modes in excellent correlation with recent theoretical results. The probable nature of the eleventh mode is discussed.