There is provided a power MOSFET in which a plurality of base regions are formed on a surface of a semiconductor region serving as a drain region, convex drain regions are formed on the semiconductor region, and a part of the convex drain regions is formed of wide bandgap semiconductor having a bandgap...http://www.google.fr/patents/US5939754?utm_source=gb-gplus-shareBrevet US5939754 - Power MOSFET having a drain heterojunction
