Optimized Design of Temperature Field in GaN Crystal Growth by the Na-Flux Method Using the Simulation Technique

In the Na-flux method for growing gallium nitride (GaN), the temperature field within the growth furnace is crucial for crystal quality. An appropriate temperature field facilitates nitrogen transport, enhances crystal growth rate, reduces defects and dislocations, and improves the optical and electrical properties of GaN crystals. Therefore, optimizing the temperature field is essential for the Na-flux method. This study employs a two-heater furnace to optimize the internal temperature field of the reaction chamber. Compared to the traditional single-heater furnace, the two-heater setup provides a more suitable temperature gradient, aiding in nitrogen transport and crystal deposition. By combining experimental data with finite element numerical simulations, the distributions of the temperature field, flow field, concentration field, and supersaturation in the crucible's melt are analyzed. Changes in upper and lower heater and temperature gradients are investigated to observe variations in mass and heat transfer within the melt. This approach aims to identify the optimal temperature curve for the two-heater furnace, achieving effective temperature field optimization. The findings provide significant theoretical support and practical guidance for future crystal growth efforts.