Growth and Characterization of High-Quality Thick Epitaxial 4H-SiC Wafers for High Voltage Devices

Silicon carbide is a leading wide-bandgap semiconductor for high-voltage power electronics. For 6.5–10 kV operation, thick epitaxial layers (≥60 µm) are required to sustain depletion width and maintain uniform electric fields, placing a premium on low extended-defect densities in both substrate and epilayer. Thick epitaxial 4H-SiC layers of 60 µm and 110 µm were grown on 6-inch substrates in a multi-wafer warm-wall reactor and evaluated by synchrotron X-ray topography in grazing-incidence (22-4 16) and transmission (11-20) geometries. Transmission imaging showed substrate dislocation content near the lower bound typically reported for 6-inch wafers. Notably, grazing-incidence topography (penetration depth >40 µm) revealed no basal-plane dislocations propagating into the epilayers, consistent with efficient dislocation conversion at the substrate– epilayer interface. The 3C-SiC inclusion density was ~30 per 6-inch wafer for 60 µm epilayers and ~60 per wafer for 110 µm epilayers; the average micropipes density varies from 0 to 5 for both 60 and 110 um epiwafers. Threading dislocation densities—screw, edge, and mixed—were on the order of 1.0–2.0 × 10³ cm⁻². These results establish thick 4H-SiC epilayers with suppressed basal-plane propagation and substantially reduced extended-defect content, providing a strong basis for reliable 6.5–10 kV device fabrication.