Optical phohon decay in bulk aluminum nitride

We report Raman studies of the E-2(2) and A(1)(LO) symmetry phonons of bulk AlN from 13 to 375 K. Based on observed dependences of the phonon energies and linewidths, and accounting for the temperature-dependent thermal expansion, we determine that both phonon lifetimes are limited by two-phonon decay. The E-2(2) decays symmetrically. The A(1)(LO) asymmetrically decays into vibrations with energies 586 and 309 cm(-1) which we attribute to A(1)(TO) and LA phonons from the M point of the Brillouin zone. (c) 2006 American Institute of Physics.