Methods and systems for operating a double-base bidirectional power bipolar transistor. Two timing phases are used to transition into turn-off: one where each base is shorted to its nearest emitter/collector region, and a second one where negative drive is applied to the emitter-side base to reduce the minority carrier population in the bulk substrate. A diode prevents reverse turn-on while negative base drive is being applied.

Bipolar junction device, and methods and switch assemblies using same. At least one example is a bipolar junction device that includes a substrate defining a first side and a second side, and a field-effect structure defined on the first side. The field-effect structure includes a channel region, a gate region in operational relationship to the channel region, and electrically insulated from the channel region, and a cathode region forming a junction with the channel region. A bipolar junction structure defined on the second side includes an injection region forming a junction with the substrate and an anode region in operational relationship to the substrate.