Depth distribution of implantation induced defects that are responsible for the well-known D-I and D-II optical emissions was investigated in nitrogen implanted and annealed SiC epitaxial layers using low temperature photoluminescence spectroscopy. It was determined that the D-I centers formed after nitrogen ion implantation and implant annealing are distributed essentially deeper in SiC layer than the D-II centers due to different origins and mechanisms of these two defects formation during implantation and annealing. The D-I photoluminescence was still observed well beyond the end on the ion penetration range, which suggests deeper penetration and/or higher diffusivity of species participating in the D-I defect formation.