VIBRATIONAL SPECTROSCOPY OF ALUMINUM NITRIDE

A complete description of the first-order Raman and Brillouin spectra of single-crystal aluminum nitride is provided. The frequency has been measured and the symmetry identified of each of the Raman-active zone-center optic modes, and the five independent elastic constants have been measured. The widths of the principal Raman modes increase with increasing oxygen content up to a critical value of approximately 1 at.%, after which they are constant. This behavior supports the hypothesis of a change in the nature of the oxygen defect at that concentration.