Excitonic structure of GaN epitaxial films grown by hydride-vapor-phase epitaxy

We report on highly resolved exciton spectra of GaN films grown by hydride vapor phase epitaxy. Using calorimetric absorption and calorimetric reflection spectroscopy the excitonic transitions originating from the A-, B-, and C-valence bands are precisely determined and the crystal-field and spin-orbit-splitting energies are calculated. We also present the first magneto-optical experiments on the neutral-donor-bound exciton. Electron as well as the hole g-values are obtained by analyzing the Zeeman splittings at 12 T.