Optical phonons in GaN

We report on all optically active phonon frequencies of wurtzite GaN determined using Raman, infrared reflection, and attenuated total reflection spectra of a high quality GaN film of 2 μm thickness. We also show results of lattice dynamical calculations using a rigid ion model. Force constants and charge as fitting parameters were determined so as to reproduce all zone-center phonon frequencies and sound velocities for the high symmetry lines. We present phonon dispersion curves and phonon density of states of wurtzite GaN.