Investigation of Optical and Structural Properties of GaN Grown by Hydride Vapor-Phase Epitaxy

Photoluminescence and reflectance experiments of high quality GaN layers grown by hydride vapor-phase epitaxy reveal narrow (2–3 meV) free and bound exciton transitions. Quenching of three acceptor-bound exciton peaks is observed with increasing film thickness (3.5–400 μm). Changes in the PL features appear to be independent of the impurity concentrations, as measured by secondary ion mass spectrometry, and the dislocation densities, obtained by photo-enhanced chemical etching. Therefore, the observed acceptor levels are assigned to intrinsic defects originating from the substrate/layer interface and decreasing in density with the thickness of the film.