Numerical insights into GaN crystal homogeneity enhancement via synergistic optimization of solution height and crucible diameter in sodium flux growth

The sodium (Na) flux method is a promising approach for the growth of high-quality, large-sized gallium nitride (GaN) single crystals, owing to its relatively mild growth conditions. However, achieving uniform crystal size and morphology remains a significant challenge. In this study, numerical simulations were employed to investigate heat and mass transport phenomena within a sodium flux system, with a particular focus on the interplay between crucible diameter and solution height. The results show that synergistic optimization of these parameters is essential for stabilizing natural convection, improving solute distribution, and enhancing mass transport, thereby promoting uniform growth of gallium nitride crystals. This study not only advances the fundamental understanding of liquid-phase epitaxial growth but also provides a validated computational framework based on computational fluid dynamics that can be extended to other crystal growth systems.