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 vo ltage drop and a leakage current level sufficiently low to allow stabl e device operation have been demonstrated. This was achieved using a c ombination of boron and aluminum as implanted acceptor for the p-type emitter. The junction termination to control the surface electric fiel d was achieved by the unintentionally induced negative surface charge. For reference, devices with a junction termination extension were als o fabricated. Both device types are shown to block the same voltage li mited 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 lat eral depletion width, which is indicative of the expected high surface charge acting on the ''self''-terminated devices as surface held redu ction. (C) 1997 Elsevier Science S.A.