Micropipe-Like Defects in the Expanded Diameter Region of 8 in. SiC Grown by Physical Vapor Transport

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 [112̅0] 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 [0001̅] 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.