Symmetry of excitons in GaN

Magnetoreflectivity measurements on GaN are used to resolve the symmetry of three excitonic resonances, arising from the crystal-field and spin-orbit effects on the valence band. The symmetry characteristic for each valence s ubband is directly seen in the observed Zeeman pattern. The linear magnetic -field effect for all exciton components is well accounted for by introduci ng only two coupling constants: the electronic g factor for the conduction band and the Luttinger kappa parameter for the valence band. The strength o f the electron-hole exchange interaction is determined. [S0163-1829(99)0853 1-8].