Pattern Fidelity of Vertically Aligned GaAs Nanowire Arrays

Bottom-up grown III-V semiconductor nanowire (NW) device components are promising structures for advanced functional electrical and optoelectronic applications, including solar energy conversion devices such as photoelectrochemical cells. The work presents a strategy for preparing highly ordered GaAs NW arrays by combining a low-cost, non-lithographic nanostructuring technique with state-of-the-art bottom-up NW growth via metal-organic vapor phase epitaxy (MOVPE). Regular gold (Au) nanodisk arrays are patterned using an ultrathin anodic alumina membrane mask and serve as catalysts for uniform NW array formation. In contrast to conventional methods such as the expansive, resin-based nanoimprint lithography, the specific fabrication process of the Au nanodisks prevents undesired substrate imprinting. While previous methods rely on a pre-anneal nucleation step to preserve pattern fidelity, It is demonstrated that this step alone is insufficient to maintain a well-ordered array. To overcome this limitation, a pre-anneal growth step that forms a GaAs pedestal, effectively anchoring the Au particles and stabilizing the array structure, is proposed. A detailed examination of the sequential MOVPE steps facilitates the development of a comprehensive growth model. The refined process paves the way for large-scale, cost-efficient production of well-ordered NW arrays, with potential for integration into solar-driven water splitting and related applications.