Epitaxial synthesis of GaN/Ga₂O₃ core/shell nanocable heterostructures by atmosphere control

One-dimensional nanoheterostructures consisting of single crystalline hexagonal GaN nanowire cores and single crystalline monoclinic Ga₂O₃ shells were synthesized epitaxially using NH₃ and O₂ gases as the reaction agents in sequence during the thermal evaporation of GaN powders. It was possible to obtain a coaxial nanocable structure with a sharp interface and a uniform smooth surface which was formed by the heteroepitaxial overgrowth of a tubular Ga₂O₃ layer in the radial direction over the GaN nanowire core. The thickness of the Ga₂O₃ shell could be controlled by changing the flow rate of the oxidizing agent O₂. The novel method introduced in this study enabled the epitaxial synthesis of coaxial GaN/Ga₂O₃ nanoheterostructures potentially suitable for the application to nanoscaled electronic device, demonstrating the advantages over conventional thermal oxidation process in terms of simplicity, morphological and geometrical controllability, and crystalline quality.