Several highly aluminum doped SiC bulk crystals were grown with a modified PVT (MPVT) method. To facilitate 4H-SiC formation, growth was conducted on the C-face. The samples were investigated using Hall measurements in the Van-der-Pauw geometry. Lowest room temperature values for specific resistivities were 0.09 Ωcm for 6H-SiC and 0.2 Ωcm for 4H-SiC, which are to our knowledge the lowest values yet reported in literature. Thus, resistivity values of < 0.2 Ωcm, which are required for substrates in high power device applications, could be demonstrated for 4HSiC. Remarkably, in very highly doped samples the type of conduction could not be determined by Hall measurements.