High-density, defect-free, and taper-restrained epitaxial GaAs nanowires induced from annealed Au thin films

In this study, we demonstrated that by using annealed Au thin films as catalysts, high-density, defect-free, and taper-restrained epitaxial GaAs nanowires were grown on GaAs (111)B substrates. The as-grown nanowires were compared with low-density Au colloidal nanoparticle catalyzed GaAs nanowires grown under identical conditions in the same metal-organic chemical vapor deposition reactor. Through detailed morphological and structural characterizations using advanced electron microscopy, we discovered that GaAs epitaxial nanowire tapering can be efficiently restrained by increasing the density of Au catalysts. By increasing the density of the Au catalysts, the axial growth rate of nanowires is reduced, which, in turn, limits the formation of lattice defects. Furthermore, the comprehensive investigation of GaAs nanowires catalyzed by Au thin film of different thicknesses (1 nm, 2 nm, 3 nm, and 5 nm) and Au colloidal particles of different densities indicates that the density of the Au catalysts play an important role in GaAs nanowire growth. This comprehensive study provides an opportunity to explore the effects of the catalysts and the growth mechanisms of III-V epitaxial semiconductor nanowires.