Investigations of inhomogeneous operation of IGB under Unclamped Inductive Switching condition

This paper reports the results of a study into inhomogeneous operation of IGBTs under Unclamped Inductive Switching (UIS) conditions. Device simulation clarified that differences in the density of holes supplied from the backside causes inhomogeneous current in IGBTs under UIS conditions. The study also measured the distribution of current within the device. A test IGBT with a variable hole density supplied from the backside was fabricated. This enabled inhomogeneous current phenomena in an IGBT under UIS conditions to be verified by actual measurements.