Three topics are reported in this paper: (a) the determination of a temperature-dependent Hall scattering factor for holes r(H,h)(T) in 4H-SiC, (b) the detection of shallow Al-related defect centers in Al-doped, p-type 6H-/3C-SiC; these defects are generated either by implantation of any ion species or by an oxidation process and (c) the observation of absorption lines in infrared (IR) spectra, which are due to phosphorus donors in 6H-SiC.