Synergistic Effect of Thermal and Flow Fields on Stress Distribution in AlN Crystal Growth by PVT

Excessive thermal stress is a serious issue that causes cracking in AlN single crystals during physical vapor transport (PVT) growth. Herein, with numerical simulations and PVT experiments, the thermal stress distribution was investigated to address the challenges in crystal growth. The free side and inclined surfaces of crystals were identified as favorable factors to reduce thermal stress. We proposed a strategy of synergistic control of the thermal and flow fields and carried out PVT growth under the conditions by combining the thermal adjustment components and the integrated flow field regulation components. A positive correlation was established between the simulated von Mises stress of the crystal and the experimentally measured crack density of the wafer. Effective synergistic control ensures a low and evenly distributed thermal stress in crystal growth, facilitating the production of high-quality, crack-free wafers.