MBBL diode: a novel soft recovery diode

A novel soft recovery diode, called middle broad buffer layer (MBBL) diode, has been investigated for the first time. It has a broad buffer layer in the middle of a N-drift region, in order to reduce the electric field strength during reverse recovery. This prevents a snappy reverse recovery, due to the large amount of remaining stored charges. The width and the donor concentration in the middle buffer layer are optimized to keep a sufficient high blocking voltage. The trade-off relationship between the reverse recovery loss and the forward voltage drops can also be improved by having soft recovery characteristics.