Geometry and Evolution of Facets in 4H-SiC Crystals Grown by Physical Vapor Transport

Facet formation during n-type SiC crystal growth leads to nonuniform dopant incorporation and resistivity variations, critically challenging the performance and reliability of SiC power devices. This work presents a systematic study combining theoretical modeling and experimental measurements to elucidate the facet geometry of 4H-SiC grown by the physical vapor transport (PVT) method. The key innovation lies in establishing a curvature-based theoretical framework that quantitatively links three representative facet shapes (circular, elliptical, and moon-shaped) to the local geometry of the growth front. Using longitudinal slices and neural-network-based fitting of growth fronts reconstructed from nitrogen demarcation lines, we precisely extracted front curvatures and facet–front distances. Our approach enables the prediction of facet evolution throughout crystal growth based solely on front geometry. This study not only advances the fundamental understanding of facet formation mechanisms but also provides practical guidelines for thermal field design and facet region control, thereby contributing to the improvement of substrate resistivity uniformity and the development of high-performance, large-diameter SiC wafers for next-generation power electronics.