  Interface phonon (IF) modes of c-plane oriented [AlN/GaN]20 and
Al0.35Ga0.65N/Al0.55Ga0.45N]20 multi quantum well (MQW) structures grown via
plasma assisted molecular beam epitaxy are reported. The effect of variation in
dielectric constant of barrier layers to the IF optical phonon modes of well
layers periodically arranged in the MQWs investigated.
