EXCITON ABSORPTION IN GAN

The absorption coefficient of the wurtzite-type GaN is described in te rms of three almost totally decoupled excitons A, B, C associated with split valence bands of Gamma(9), Gamma(7) and Gamma(7) symmetries usi ng a spherically symmetric approximation for the standard effective-ma ss Hamiltonian. The excitonic equations are solved within the subspace of optically active states of s-symmetry. The effects of crystal fiel d and spin-orbit coupling are discussed. The results show that the sph erical approximation is in perfect agreement with experimental finding s.