Abstract: β-Ga₂O₃ single crystals exhibit exceptional properties, such as a wide bandgap and high breakdown field strength, making them highly valuable for applications in high-power and deep ultraviolet devices. The edge-defined film-fed growth (EFG) method is a critical technique for producing large and high-quality β-Ga₂O₃ single crystals. However, the circumferential symmetry of the heating and insulation structure inside the EFG furnace, coupled with the circumferential asymmetry of the die and the crystal, leads to significant heat transfer non-uniformity in the width and thickness directions of the crystal, resulting in severe crystallization interface deformation that impairs the stable growth of the crystal. This study comprehensively considers various heat transfer phenomena, including the coupling effects of anisotropic thermal conductivity and thermal radiation absorption in β-Ga₂O₃ single crystals. A dynamic mesh tracking method is implemented to model non-axisymmetric crystallization interface shapes, and a three-dimensional global heat transfer numerical model is developed for the EFG growth of β-Ga₂O₃ single crystals. The heat transfer and crystallization interface deformation during the growth of 2-inch and 6-inch (1 inch=2.54 cm) β-Ga₂O₃ single crystals were compared and analyzed. Interface deformation for crystals of different sizes was evaluated, and a cover structure was designed to reduce deformation during the growth of 6-inch crystals. The results show that the growth of 6-inch β-Ga₂O₃ single crystals exhibits more significant heat transfer non-uniformity in the width and thickness directions of the crystal. This results in larger crystallization interface deformation and poorer crystal growth stability for larger crystals. The cover structure has a significant influence on both heat transfer in the width and thickness directions of the crystal and interface deformation. A thick cover that circumferentially wraps the crystal can create favorable conditions for the stable growth of 6-inch β-Ga₂O₃ single crystals. This research provides valuable guidance for ensuring the stable growth of large, high-quality β-Ga₂O₃ single crystals by the EFG method.

Key words: edge-defined film-fed growth (EFG) method, β-Ga₂O₃ single crystal, anisotropic thermal conductivity, thermal radiation absorption, crystallization interface deformation, heat transfer