Micro-Raman studies of Zincblende MgS

Recent improvements in UV Raman spectrometer capability have resulted from the availability of much improved dielectric filters, and we can now observe directly both the longitudinal and the transverse optic phonon modes of the wide-bandgap zincblende semiconductor MgS. We are, thus, able to confirm the earlier measured and calculated phonon frequencies with improved accuracy. The strong sequence of overtone modes that we observe is interpreted in terms of the resonance behavior of the Raman scattering process at this excitation energy. The spectra also show features which, by comparison to ab-initio calculations of the phonon dispersion and density of states, can be identified as arising from multiple Raman scattering processes involving longitudinal acoustic phonons near the Brillouin zone boundary.