We have estimated the free-carrier concentration and drift mobility in n-type 6H-SiC wafers in the carrier concentration range of 1017–1019 cm-3 from far- and mid-infrared (30–2000 cm-1) reflectance spectra obtained at room temperature. A modified classical dielectric function model was employed for the analysis. We found good agreement between the electrical properties derived from infrared reflectance spectroscopy and those derived from Hall effect measurements. We have demonstrated the spatial mapping of carrier concentration and mobility for commercially produced 2 inch SiC wafers.

Infrared reflectance spectroscopy has been used to characterize the electrical properties and crystalline damage of high-dose implanted and post-implantation-annealed 4H-SiC. The carrier concentration, mobility and crystalline damage were independently derived from the analysis of the infrared reflectance spectra using the effective medium approximation and the modified dielectric function taking into account the TO and LO phonon damping factors independently. The carrier concentration and mobility in the recrystallized SiC derived from infrared reflectance spectra are in good agreement with those obtained from Hall effect measurements. The annealing temperature dependence of crystalline damage suggests that the impurities are almost activated by the annealing at a temperature as low as 1200°C for 30 min, though the crystallinity of the implanted layer is improved with increasing annealing temperature. In addition, it is revealed that the annealing at a temperature as high as 1700°C recovers the crystallinity of the implanted layer within 1 min. These results demonstrate that the infrared reflectance spectroscopy is a useful technique to characterize both the electrical properties and crystalline damage of implanted and post-implantation-annealed layers in SiC wafers simultaneously.

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