This study presents the growth of 8 in. silicon carbide
(SiC) single
crystals using a multiple-expanding diameter growth process via the
physical vapor transport technique, with commercial 6 in. n-type SiC
of 4° off-axis toward [11
0] as the seed. Micropipe-like defects were observed in the expanded
diameter region, whereas they are absent in the unexpanded diameter
region grown on the SiC seed via step-flow growth mode. Optical microscopy,
scanning electron microscopy, micro-Raman spectroscopy, laser scanning
confocal microscopy, defect-tracking experiments, and energy-dispersive
spectroscopy were employed to investigate the morphology, polytype,
and formation mechanism of the defects. The micropipe-like defects,
with diameters in the dozens of micrometers scale and an angle ∼50°
relative to the [000
] direction, were found to stem from carbon particles decomposed
from SiC powders. No other polytype inclusions were observed in these
defects. By applying sintered SiC powders as starting materials, micropipe-like
defects were effectively reduced. Our results provide an efficient
method for growing large-size SiC single crystals of high-quality
and low-defect density via the multiple-expanding diameter growth
process.