We report a comparative investigation of the activation kinetics of nitrogen and phosphor-us ions implanted at room temperature in 4H-SiC semi-insulating substrates. We characterised the electrical activation through a fast non-contact method (eddy current) which gives the sheet resistance after every annealing step. The surface roughness was monitored by AFM. The crystal recovery was characterised by Raman spectroscopy. For a given annealing temperature, we show that, the N+-implanted sample reaches always a maximum activation rate at a shorter time (similar to3 times less) than the P+-implanted one. We find also that the best activation results are not obtained by using simply N+ or P+ but rather a co-implantation of N+ and P+ to the same dose.