4H- and 6H-SiC small samples were implanted by keV Al+ ions at room temperature and annealed in an induction heating furnace, at the center of the susceptor, for different temperatures and times in the range 1600-1800degreesC and 5-60 min, respectively. The implanted layers were amorphous but the SiC crystalline structures were recovered after annealing, as measured by Rutherford Back-Scattering analyses in Channeling geometry. Al+ electrical activation determined by sheet resistance and Hall effect measurements increases with the annealing temperature or time, on both polytypes. When whole SiC wafers were annealed in the same induction heating furnace, sheet resistance mapping systematically presented a radial gradient from the center to the periphery of the wafer. The measured linear dependence between sheet resistance and temperature allowed us to rebuild the radial temperature gradient at the crucible-susceptor furnace during the annealing process.