Suppression of gallium inhomogeneity in ZnO nanostructures on GaN using seed layers

Using two different types of seed layers, ZnO nanostructures were grown on c-plane GaN. Atomic force microscopy and scanning electron microscopy were used to characterize the morphology of the seed layers and of the ZnO nanostructures. Well-faceted ZnO nano-pillars and nano-needles can be grown on two different seed layers, respectively. Spatially and spectrally resolved cathodoluminescence (CL) was recorded to probe single ZnO nanostructures. The CL spectra of the ZnO nanostructures are dominated by the gallium donor bound excitons, which show uniform gallium incorporation along the growth direction. For the ZnO nano-pillars we find strong gallium in-diffusion, whereas the ZnO nano-needles show less gallium diffusion. (C) 2012 Elsevier B.V. All rights reserved.