Mechanism for enhanced single-crystal GaN growth in the C-assisted Na-flux method

• Published in: Applied physics express Vol. 9; no. 1; pp. 15601 - 15604
• Main Authors: Kawamura, Takahiro, Imabayashi, Hiroki, Maruyama, Mihoko, Imade, Mamoru, Yoshimura, Masashi, Mori, Yusuke, Morikawa, Yoshitada
• Format: Journal Article
• Language: English
• Published: The Japan Society of Applied Physics 01.01.2016
• ISSN: 1882-0778; 1882-0786
• DOI: 10.7567/APEX.9.015601

First-principles molecular dynamics simulations are used to examine the effect of C addition in Na-flux growth of GaN. The mechanism for suppression of polycrystalline growth and the enhancement of single-crystal growth was identified by systematically calculating activation free energies for the formation and dissociation of C-N bonds. The energy barrier for C-N dissociation in a Ga-Na melt is ≥3 eV; thus, dissociation is inhibited and the growth of polycrystals is suppressed. However, at kink sites at a Na/GaN interface with excess Ga atoms, the barrier is only ∼1.0 eV, allowing C-N dissociation and growth of GaN single crystals.