Phosphorus (P) ion implantation into 6H-SiC at elevated temperatures and subsequent annealing up to 1700 degreesC has been performed. Relationship between the electrical activation of P atoms and the recovery of defective layers was investigated by Hall effect measurements and positron annihilation spectroscopy. Clustering of vacancy-type defects due to post-implantation annealing is suppressed by implantation at elevated temperatures. The implantation temperature dependence of the carrier concentration in the samples can be interpreted in terms of annealing behavior of residual defects.