Bidirectional blocking junctions in SOI

Back-to-back junction (n-p-n) structures were fabricated in silicon-on-sapphire (SOS), in polysilicon-on-SiO₂, and in silicon-on-insulator (SOI) prepared by high-dose oxygen ion implantation. Since the structure is actually a bipolar transistor operated with an open base, the geometry and doping levels were adjusted to spoil its gain and thereby achieve symmetrical bidirectional blocking. In all three cases, ideal plane-junction breakdown was observed for both polarities of applied voltage when precautions were taken to avoid local field-enhancing geometries.