Zeldovich Nucleation Rate, Self-Consistency Renormalization, and Crystal Phase of Au-Catalyzed GaAs Nanowires

• Published in: Crystal growth & design 2015-01, Vol.15 (1), p.340-347
• Main Authors: Dubrovskii, V.G, Grecenkov, J
• Format: Article
• Language: English
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg5014208

We present a self-consistent model for the Zeldovich nucleation rate that determines the nucleation probabilities, growth rates, and even the preferred crystal structure of Au-catalyzed III–V nanowires fabricated by the vapor–liquid–solid growth method. The obtained expression accounts for the nucleation kinetics in ternary Au–III–V alloys and shows that the nucleation rate in vapor–liquid–solid nanowires is proportional to the As concentration, As diffusion coefficient in the droplet, and activity of solid GaAs. The leading exponential term of the nucleation rate is modified due to the self-consistency renormalization. As a result, the behavior of the effective nucleation barrier versus Ga concentration is changed significantly with respect to the commonly used expression. This strongly affects the values of Ga concentrations during growth which are obtained within the self-consistent approach with the known nanowire elongation rates. In turn, the renormalized nucleation rates change the predictions regarding the zincblende–wurtzite phase transitions in III–V nanowires. In particular, our calculations show why the Au-catalyzed GaAs nanowires grown by molecular beam epitaxy at 550 °C are predominantly wurtzite, while the high temperature hydride vapor phase epitaxy at 715 °C yields pure zincblende crystal structure. We also obtain useful estimates for the As diffusion coefficients in ternary Au–Ga–As liquids at different conditions.