Phonons in a strained hexagonal GaN--AIN superlattice.

Studies the vibration modes of gallium nitride-AlN superlattice grown by molecular beam epitaxy on a sapphire substrate and an AlN buffer layer by micro-Raman spectroscopy. Frequency shift of phonons; Average strain value in GaN layers; Strain relaxation percentage of GaN layers lying close to the interface with the buffer layer.