LATTICE-DYNAMICS OF GAN ALN SUPERLATTICES

Phonon dispersion curves of cubic (001)-(GaN)(n)/(AlN)(n) (n=1-4) supe rlattices for various propagating directions are calculated. Short-ran ge interactions up to the second-nearest neighbors are described by us ing a two-parameter Keating model, and the long-range Coulomb interact ions are included via an Ewald summation. Raman spectra are calculated by a bond-polarizability model. The confinement of optical modes is d iscussed. The anisotropies of the zone-center optical phonons are inve stigated. (C) 1997 American Institute of Physics.