Growth of 6 Inch Diameter β-Ga2O3 Crystal by the Vertical Bridgman Method

A 6 inch beta-gallium oxide (beta-Ga2O3) single crystal is grown in the < 010 > direction using the vertical Bridgman (VB) method under an oxygen partial pressure of 50%. Although cracks are observed along the cleavage planes, crossed polarizer microscopy confirms the absence of grain boundaries in the wafers. X-ray rocking curve measurements demonstrate a consistent level of crystal quality, with an average full width at half maximum of 22.56 arcsec. Observation of the quenched solid-liquid interface reveals a slightly convex shape. The actual growth rate, calculated from the experimental data, suggests that crystal growth does not fully keep pace with the crucible descent process. The effect of the furnace temperature gradient is investigated by comparing a higher gradient (4-15 degrees C cm-1) with a lower gradient (0.5-5 degrees C cm-1). The crystal grown under the higher gradient exhibits no grain boundaries, whereas those grown under the lower gradient shows grain boundaries and significant cracking, making it unsuitable for wafer processing. These results demonstrate the feasibility of growing 6 inch beta-Ga2O3 single crystals using the VB method and suggest that further optimization of conditions, including control of the temperature gradient, are essential to achieve higher quality and greater stability.