Effect of doping on the Raman scattering of 6H-SiC crystals

Raman spectra of Al- and N-doped 6 H-SiC crystal samples with different doping levels were measured. The first-order Raman spectra of the samples were shifted to higher frequency when the doping concentrations were increased. Compared with Al-doped samples, the intensity of A1 longitudinal optical mode of N-doped ones changed obviously, which reflected the different doping concentrations. The second-order Raman spectra were not dependent on the doping types and concentrations.