  Compound semiconducting nanowires are promising building blocks for several
nanoelectronic devices yet the inability to reliably control their growth
morphology is a major challenge. Here, we report the Au-catalyzed
vapor-liquid-solid (VLS) growth of GaN nanowires with controlled growth
direction, surface polarity and surface roughness. We develop a theoretical
model that relates the growth form to the kinetic frustration induced by
variations in the V(N)/III(Ga) ratio across the growing nanowire front. The
model predictions are validated by the trends in the as-grown morphologies
induced by systematic variations in the catalyst particle size and processing
conditions. The principles of shape selection highlighted by our study pave the
way for morphological control of technologically relevant compound
semiconductor nanowires.
