Free energy of nucleus formation during growth of III–V semiconductor nanowires

An expression for the free energy of forming an island from a catalyst droplet in the vapor-liquid-solid growth of III–V nanowires is obtained. The effect of the droplet depletion with its group V (As) content is studied in the presence of material influx from vapor. Different growth regimes of a nanowire monolayer are theoretically analyzed, including the regime with the stopping size under very low As concentrations in liquid. It is shown that the island stops growing when the As content in the droplet decreases to its equilibrium value. The obtained results should be useful for understanding and modeling the growth kinetics of III–V nanowires, their crystal phase, nucleation statistics and length distributions within the ensembles of nanowires as well as the doping process.