Figure 5From: The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescenceEL spectrum of n-ZnO/p-GaN and n-ZnO/NiO/p-GaN. (a) ZnO nanorods and (b) ZnO nanotubes. Insets show digital photographs of ZnO nanorod- and nanotube-based LEDs with NiO buffer layer.Back to article page