Phonon Engineering to Modify Acoustic Phonon Velocity in Hexagonal Layered Superlattices

This letter presents the possibility of using the effective medium model coupled with the piezoelectric stiffening to quantitatively explain and engineer acoustic phonons as a heat dissipation channel in GaN-based devices. These effects will be described for a GaN/AlN superlattice that exhibits enhanced acoustic phonon velocities as compared with bulk GaN. We numerically calculate the stiffened elastic constant values and apply them within the effective medium model for elastic constants. With the recent advances in epitaxial GaN growth technology, it may be possible to consider this phonon engineering option to investigate the effect on the longitudinal sound velocity to increase the rate of heat transport in GaN/AlN superlattice.