Cathodoluminescence studies of in-plane and in-depth properties of GaN epilayers

Abstract

The influence of sample morphology on optical properties of GaN epilayers is studied. We show that a granular/columnar structure of MOCVD- and MBE-grown films results in strong planar fluctuations of the “edge” emission of GaN, which is strongly deactivated at grain boundaries. In contrast, the yellow emission of GaN is relatively in-plane homogeneous. We further show large in-depth inhomogeneity of GaN samples and discuss a possible origin of in-plane homogeneity of the yellow photoluminescence.