Switching semiconductor with two opposite conductivity layers - has two more layers of alternating conductivity forming three pn-junctions, and two main electrodes

摘要

The pnpn four-layer switching semiconductor, such as switching-off thyristor has three layers of alternate conductivity on one substrate surface. Thus the first and second layer formaa first pn-junction, the second and third layer a second pn-junction, and the third layer forms a third pn-junction with a fourth layer on the other main surface of the substrate. The first semiconductor layer carries a main electrode in ohmic contact, while the fourth layer carries a second similar main electrode. A control electrode is in ohmic contact of a free surface of the second semiconductor layer which is thicker than the third layer. Preferably the second semiconductor layer is composed of two partial layers, one with low and one with a high specific resistance.