Epitaxial growth of bottom-crosslinked ZnGa2O4 nanowire arrays on c-plane GaN/Al2O3 substrate

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The epitaxial growth of highly ordered ZnGa2O4 nanowire arrays and the construction of connectivity states between the individually segregated nanowires would significantly improve the performance of ZnGa2O4-based devices and expand their application fields. Herein, a strategy to construct high crystalline quality and well-aligned bottom-crosslinked ZnGa2O4 nanowire arrays along seven equivalent crystallographic directions of [111], [111̅], [11̅1], [1̅11], [11̅1̅], [1̅11̅] and [1̅1̅1] on Au-coated (0001) GaN/Al2O3 substrates using chemical vapor deposition (CVD) is proposed. The vapor-liquid-solid (VLS) mechanism dominates the entire growth process. The horizontal nanowires induced to nucleate and grow by catalyst droplets encountered and then turned towards inclined nanowires. Meanwhile, catalyst droplets that failed to move horizontally were enclosed by horizontal nanowires, resulting in the induction of perpendicular nanowire growth. The film-like horizontal nanowires connected all the inclined and perpendicular nanowires to form the bottom-crosslinked nanowire arrays. Additionally, the morphology, structure and optical properties of the ZnGa2O4 nanowire arrays, as well as the influence of Au layer thickness and growth time on the growth of ZnGa2O4 nanowires, were further characterized and thoroughly investigated. The proposed strategy achieved the growth of epitaxial well-aligned ZnGa2O4 nanowire arrays with bottom cross-linking, which is conducive to the application of ZnGa2O4 nanowires in optoelectronics.