Effect of crucible location on heat transfer in GaN crystal growth using Na flux method

A global model of heat transfer, considering convection, conduction, radiation as well as mass transfer, is established for GaN single crystal growth system employing the Na flux method. Global simulations are carried out to investigate the effects of crucible locations on the heat and mass transfer during growing. It was found that the crucible location has a significant effect on the heat transfer in the melt. When the crucible moves down, the flow in the upper region of melt is enhanced, while that near the crucible bottom is weaken. This flow structure leads to high supersaturation at the crucible bottom, which is favorable to accelerate crystallization. Therefore, it can be concluded that the crucible location should be lowered properly to achieve a better condition for crystallization. The research provides directions to the design of GaN growing systems.