High-voltage implanted 4H-SiC p(+)n diodes have been studied by means of electron beam induced current (EBIC) measurements for reverse voltages in the kV-range. Several EBIC investigating techniques were employed in different planar and cross-section geometries. A mapping of the multiplication coefficient revealed that the current through some defects saturates above a certain negative bias, causing a reduction in the multiplication of the electron beam generated charge carriers. By comparing EBIC images with optical images from CCD measurements, the presence of defects exhibiting an increased current without a corresponding increase in light emission can be detected. Finally, the diffusion length of holes in the low doped region close to the pn-junction was estimated to be 1.5 mum.