2.5 kV ion-implanted p(+)n diodes in 6H-SiC

High-voltage diodes which can block up to 2.5 kV have been fabricated by ion implantation of p-type dopants. Junctions with a low forward voltage drop and a leakage current level sufficiently low to allow stable device operation have been demonstrated. This was achieved using a combination of boron and aluminum as implanted acceptor for the p-type emitter. The junction termination to control the surface electric field was achieved by the unintentionally induced negative surface charge. For reference, devices with a junction termination extension were also fabricated. Both device types are shown to block the same voltage limited by external flash-over. Using optical beam induced current (OBIC) measurements, we visualized the depletion region of the implanted pn junctions and found that all devices have a considerably enlarged lateral depletion width, which is indicative of the expected high surface charge acting on the ''self''-terminated devices as surface held reduction. (C) 1997 Elsevier Science S.A.