Infrared Lattice Absorption in Wurtzite GaN

Two-phonon absorption spectrum of wurtzite GaN was measured for the first time and was compared with two-phonon density-of-states of zincblende GaN obtained by lattice-dynamical calculations with an adiabatic bond-charge model. All structures in the spectrum were well explained by phonon structures of zincblende GaN. As a method to analyze two-phonon absorption spectra of wurtzite materials, proposed was the utilization of phonon dispersion curves of corresponding zincblende modifications, and the method was found to be useful.