Automatically scanned IV and CV measurements were performed for mapping characterization on the substrate and epitaxy layer 4H-SiC. Mapping results of n-value, SBH and breakdown voltage on the substrate were observed to match well with X-ray topographic image, where the presence of defects on its surface strongly modified the IV characteristic as well as breakdown voltage. The defects on the substrate were also found to crucially determine the breakdown voltage of grown epitaxy layer. Carrier density in the substrate was observed to be highly concentrated in the wafer-center, while it was distributed along a forward direction in the epitaxy layer. Gas flow direction was assumed as a major reason for non-uniformity. The rotation of wafer holder during epitaxy growth might be needed for achieving uniformity of net-doping concentration.