Dual-base two-sided bipolar power transistors which use an insulated field plate to separate the emitter/collector diffusions from the nearest base contact diffusion. This provides a surprising improvement in turn-off performance, and in breakdown voltage.

A method of operating a bipolar transistor having a source, a drain, and a channel electrically coupled to the source and the drain includes applying a bias voltage to a gate electrically coupled to the channel, increasing a conductivity of the channel via field ionization in response to applying the bias voltage, and conducting current from the source to the drain

The present application teaches, among other innovations, power semiconductor devices in which breakdown initiation regions, on BOTH sides of a die, are located inside the emitter/collector regions, but laterally spaced away from insulated trenches which surround the emitter/collector regions. Preferably this is part of a symmetrically-bidirectional power device of the B-TRAN type. In one advantageous group of embodiments (but not all), the breakdown initiation regions are defined by dopant introduction through the bottom of trench portions which lie within the emitter/collector region. In one group of embodiments (but not all), these can advantageously be separated trench portions which are not continuous with the trench(es) surrounding the emitter/collector region(s).