Filtering and Interfacial Interaction Mechanism of TaC for Carbon Inclusions Suppression in PVT-Grown SiC Crystals

The presence of carbon inclusions, originating from the nonstoichiometric sublimation of source materials, poses a significant challenge to the quality of silicon carbide (SiC) single crystals grown by the physical vapor transport (PVT) method. To address this issue from a metallurgical process control perspective, this study investigates the application of a filtration structure based on tantalum carbide (TaC). TaC particles were synthesized, and their interfacial evolution during the crystal growth environment was systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Results revealed that carbon is progressively adsorbed onto the TaC particles, forming a surface layer. Crucially, the filtration performance is closely related to the surface state of the TaC. Under improper growth conditions, excessive carbon thickening turns the surface from golden-yellow to black-gray, severely impairing its adsorption capacity. Density functional theory (DFT) calculations corroborate that golden-yellow TaC exhibits a markedly higher carbon adsorption energy (-1.46 eV) than its black-gray state counterpart (-0.82 eV). Crystal growth experiments further demonstrate that maintaining TaC in the golden-yellow state enables stable dynamic filtration during 4H-SiC growth. The resulting 4H-SiC wafers exhibit excellent polytype stability, high crystalline quality, ultralow carbon inclusion density, and extremely low dislocation density. These results confirm the practical feasibility of TaC-based filtration for high-quality, low-defect SiC substrate fabrication. This work not only provides an effective strategy for defect control in SiC crystal growth but also clarifies the underlying mechanisms─specifically, the structure-activity relationship of TaC and its interfacial interaction with C during high-temperature vapor-phase adsorption─thus advancing its practical application in advanced semiconductor material preparation.