Comprehensive Structural and Interfacial Characterization of Laser-Sliced SiC Wafers

Laser slicing has emerged as a promising low-kerf and low-damage technique for fabricating SiC wafers; however, its influence on crystal integrity, near-surface modification, and charge-transport properties requires further clarification. In this study, a heavily N-doped 4° off-axis 4H-SiC wafer was sliced using a UV picosecond laser, and both the laser-irradiated surface and the laser-sliced (detached) surface were comprehensively characterized. X-ray diffraction and pole-figure measurements confirm that the 4H stacking sequence and macroscopic crystal orientation are preserved after slicing. Raman spectroscopy, including analysis of the folded transverse optical (FTO) mode and LO phonon–plasmon coupled (LOPC) modes, enabled dielectric-function fitting and determination of the plasmon frequency, yielding a free-carrier concentration of approximately 3.1 × 10¹⁸ cm⁻³. Hall measurements provide consistent carrier density, mobility, and resistivity, demonstrating that the laser slicing process does not degrade bulk electrical quality. Multi-scale AFM, angle-resolved XPS, SIMS, and TEM/SAED reveal the formation of a thin amorphous/polycrystalline modified layer and an oxygen-rich region confined to the near surface, with significantly increased roughness and thicker modified layers on the hill regions of the sliced surface. These results show that UV laser slicing maintains the intrinsic crystal and electrical properties of 4H-SiC while introducing localized nanoscale surface damage, which must be minimized through optimized slicing parameters and subsequent surface-finishing processes.