Phonon polaritons in uniaxial crystals: A Raman scattering study of polaritons in α-GaN

摘要

We present Raman scattering results on phonon polaritons in single crystals of a-GaN. A detailed theoretical treatment of their dispersion and Raman scattering efficiency in wurtzite-type crystals is given. Pure symmetry polaritons (ordinary and extraordinary) are accessible in near-forward scattering geometry according to the theory. For this purpose, the experimental setup uses rectangular aperture windows in front of the entrance lens. Thus measurements with well defined wave-vector transfer can be realized. The observed dispersion curves and scattering efficiency results are compared with theoretical ones and are found to be in excellent agreement.