Exciton energy structure in wurtzite GaN

Results of theoretical and experimental magneto-optical studies of free exc itons in wurtzite GaN are presented. The direct photoluminescence from free exciton states of high-quality GaN epilayers was studied by polarization-d ependent magneto-optical measurements in magnetic fields up to 15 T. Zeeman splittings and diamagnetic shifts of the n = 1 and n = 2 slates of the A e xciton were observed for magnetic fields parallel and perpendicular to the hexagonal axis. The experimental data are described by a theory of the exci ton energy structure in hexagonal semiconductors with wurtzite symmetry in the framework of the quasi-cubic approximation.