Piezoelectric Polarization Effect And Phonon Relaxation Rates In Binary Wurtzite Nitrides

The piezoelectric (PZ) polarization property present in the wurtzite nitrides modifies the group velocity of phonons. As a result, the relaxation rates of phonons are changed. In this paper, we have calculated the relaxation rate of phonons as functions of the phonon frequency in binary wurtzite nitrides (GaN, AlN and InN) using the modified phonon group velocity. Different scattering mechanisms such as Umklapp, point defect, dislocation, boundary and phonon-electron scattering processes have been considered. The percentage change in phonon relaxation rates is found to be maximum for InN and minimum for GaN. This result can be used to study the effect of PZ polarization property on thermal conductivity of these materials.