Scanning electron microscope studies using secondary electrons and electron beam induced current (EBIC) modes are reported For prototype p-i-n structures developed For high-power applications. It is observed that the diffusion length values in such devices are of the order of 0.5 0.8 mu m and show considerable variations along the p n junction plane as also is the case for the thickness of the space charge region near the p i interface. Unidentified defects manifesting themselves even at low applied reverse biases and giving rise to a strong bright contrast in EBIC images of the cleaved diodes have been also detected. Their surface density has been estimated to be not lower than 10(3) cm(-2).