Abstract: β-Gallium oxide (β-Ga₂O₃) has emerged as a promising wide bandgap semiconductor. However, the growth of high-quality, large-sized single crystals still remains challenging, particularly in the controllable growth orientation. While the [010] pulling direction dominates current methodologies, the physical mechanism governing orientation selection remains poorly understood. Based on thermal theory, this paper simulates the temperature field distribution of the growth along the [010] and [100] directions. The symmetry of the growth process is evaluated by the average temperature gradient. The temperature field of the large surface (010) growing along the [100] direction shows obvious asymmetry. The large surface (100) growing along the [010] direction is a quasi-symmetrical form, not a perfect symmetrical face. Through theoretical calculations, it was found that it is necessary to rotate the crystal by 16.09° around the [010] direction axis to enable it to grow with optimal symmetry. In order to maintain the crystal symmetry during the growth process, a process optimization scheme of continuously reducing the shoulder angle is proposed. The accuracy of thermal field analysis was verified through two sets of growth experiments with different orientations. This work advances the mechanistic understanding of the orientation-dependent growth phenomenon in β-Ga₂O₃ crystal.

Key words: β-Ga₂O₃ crystal, Growth orientation, Symmetry, Average temperature gradient