The forward current conductions of the planar junction diodes fabricated on 4H-SiC were analyzed in relation to defects. The forward current conduction above 2V followed the well-known exponential dependence for forward voltage. However, below 2V, some types of "excess current" were revealed. We classified these "excess currents" and found that some were related to micropipe defects, and the others were related to space-charge limited currents.