We report on the electroluminescence (EL) measured for forward biased 4H SiC pn diodes formed by Al+ or B+ implantation into n-type epitaxial layers. We have measured EL spectra for these pn diodes with high and low leakage currents. Diodes with low leakage current showed a steep increase in 390nm peak with current injection compared to those from donor acceptor pair (DAP) or defect related recombination, whereas the diode with high leakage current showed a relatively slow increase in 390nm peak. We found the correlation between high leakage current and small "free to bound" EL peak.