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.