We have synthesized ternary InGaAs nanowires on (111)B GaAs surfaces by metal-organic chemical vapor deposition. Au colloidal nanoparticles were employed to catalyze nanowire growth. We observed the strong influence of nanowire density on nanowire height, tapering, and base shape specific to the nanowires with high In composition. This dependency was attributed to the large difference of diffusion length on (111)B surfaces between In and Ga reaction species, with In being the more mobile species. Energy dispersive X-ray spectroscopy analysis together with high-resolution electron microscopy study of individual InGaAs nanowires shows large In/Ga compositional variation along the nanowire supporting the present diffusion model. Photoluminescence spectra exhibit a red shift with decreasing nanowire density due to the higher degree of In incorporation in more sparsely distributed InGaAs nanowires.

What's in a wire? To determine the fundamental reason for obtaining tapered nanowires, GaAs nanowires were grown on {111}B GaAs substrates. Their novel structural characteristics (e.g., a truncated triangular cross section at the base of the nanowires; see image) were carefully investigated using high‐resolution SEM and various TEM techniques. Based on the obtained structural characteristics of these nanowires and the growth environment, an asymmetrical lateral‐growth mechanism has been identified.