Three-Dimensional (3D) Nondestructive Characterization of the Spatial Distribution and Complex Properties of Polytypes on 4H-SiC Wafers

4H-SiC is a leading third-generation material, and the physical vapor transport (PVT) method is the most commonly used and the most suitable for the industrial growth of bulk SiC crystals. However, because the occurrence of polytyping is still common during SiC growth by the PVT method, the identification and analysis of polytypes on 4H-SiC single crystals are very necessary. Optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and spectroscopic analyses (microscopic Raman spectroscopy, photoluminescence (PL), and cathodoluminescence (CL)) were carried out to validate and compare the newly proposed methods. Subsequently, two-photon photoluminescence (2PPL) and differential interference contrast confocal laser scanning microscopy (DIC-CLSM) were employed for the first time in this study to characterize and analyze polytype regions. Three-dimensional (3D) fluorescence characterization and 3D stress analysis of 4H, 6H, and 15R polytypes and polytype grain boundaries were successfully completed, and the spatial morphology of carbon inclusions on the polytype grain boundaries and defect clusters on the polytypes were briefly studied. The superiority of two-photon fluorescence microscopy for the characterization of the spatial distribution of 4H-SiC polytypes is confirmed by this study. This study enriches the means of identifying polytypes in 4H-SiC wafers and provides new ideas for analyzing the distribution of polytypes in 4H-SiC.