Numerical Simulation of the Influence of Various Crucible Sizes and Shapes on the Growth of GaN Crystals by the Na-flux Method

This study employs numerical simulation to comprehensively investigate the impact of crucible size and shape on the heat transfer, mass transfer, and convective dynamics involved in GaN crystal growth using the sodium flux method. The findings demonstrate that larger crucibles, owing to their smoother temperature gradients, facilitate enhanced convective flow and more efficient solute transport, leading to improved uniformity in the crystal growth process. Smaller crucibles, by contrast, exhibit steeper temperature and concentration gradients, which may negatively impact both solute transport and growth rates. In terms of crucible shape, steeper wall angles increase the temperature gradient in the upper regions of the melt, promoting nitrogen transport but potentially leading to localized overheating and solute accumulation. Conversely, gently sloped crucibles provide a more uniform heat distribution, creating more stable conditions conducive to homogeneous crystal growth. The optimization of crucible geometry, in terms of both size and shape, is thus critical for achieving higher-quality, larger GaN crystals. This research offers valuable theoretical insights that can guide the design of future experimental setups, contributing to advancements in crystal growth techniques and material quality.