A technique for diameter enlargement in SiC crystal growth

The availability of large high-quality silicon carbide (SiC) single crystals is a key issue in the development of the full potential of SiC-based device technology. This paper mainly discusses SiC crystal growth in the graphite crucible with several geometrical structures by using the physical vapor transport method to investigate the influence of graphite crucible structures on SiC crystal diameter enlargement. Metallographic microscopy and X-ray diffraction are applied to the obtained cross-sectional slice of SiC ingot. In a growth run with a crucible structure of cylinder platform seed-holder and additional cone-shaped inner furnace close to the seed crystal, the SiC crystal diameter increases only 4-5 mm and the growth front exhibits a smooth segment of spherical shape; but the diameter of SiC single crystal decreases when the inside diameter of the crucible is close to that of the seed crystal and the angle a between the cone-shaped platform and cylinder platform is larger than 20 degrees. When using the crucible with a cone-shaped platform seed-holder and cone-shaped inner wall, the SiC crystal growth will proceed along the axial direction as well as the radial direction, and the diameter can be enlarged by about 12 mm in a single growth run.