Novel characterization method for the nitrogen doping concentration in heavily nitrogen-doped 4H-SiC crystals by Raman scattering microscopy

A novel characterization method for the nitrogen doping concentration in heavily nitrogen-doped (more than 1 × 1019 cm−3) 4H-SiC crystals using Raman scattering microscopy is proposed. The method utilizes the integrated intensity of the longitudinal optical phonon-plasmon coupled (LOPC) mode signal arising at 1100 cm−1, which exhibits marked changes in the peak position, intensity, and line shape when the nitrogen concentration in 4H-SiC crystals changes. The proposed method showed a much higher sensitivity to the nitrogen doping variation in 4H-SiC crystals compared to the conventional characterization methods using the LOPC peak shift and the Fano interference, and detected a small variation (~1%) in the nitrogen doping concentration across the (000) facet of heavily nitrogen-doped 4H-SiC crystals.