Properties of GaN and related compounds studied by means of Raman scattering

In the last decade, we have seen very rapid and significant developments in Raman scattering experiments on GaN and related nitride compounds: the Γ-point phonon frequencies have been identified for both cubic and hexagonal structures of binary compounds of GaN, AlN, and InN. The phonon spectra of their ternary alloys, InGaN and AlGaN, were also intensively studied. On the basis of these studies, characterizations of strain, compositional fluctuation, defects, impurities, etc, are now being intensively conducted. Besides such pure lattice properties, coupled modes between a lattice vibration (LO phonon) and a collective excitation of free carriers (plasmon) in GaN have been thoroughly studied, and the results…