Quality control of GaAs nanowire structures by limiting as flux in molecular beam epitaxy

In this study, we demonstrate that by merely limiting the As flux, the growth behavior and structural quality of Au-catalyzed GaAs nanowires can be modulated in molecular beam epitaxy. With decreasing the As flux through lowering the V/III ratio, GaAs nanowire growth is found to be slow and defect-free wurtzite structured GaAs nanowires can be obtained regardless of catalyst sizes. While, in the As-enriched environment (such as at relatively high V/III ratio), thinner nanowires can grow longer with fewer planar defects. Based on our extensive morphological, structural, and compositional investigations, it is found that GaAs nanowires grown under an As-limited condition can lead to a thermodynamically controlled growth process, while, when the nanowires are grown under a relative high V/III ratio, a typical kinetically dominated process is observed. This study provides a new insight for controlling the structural quality of III–V nanowires by tuning the group-V flux