Abstract: A two-way semiconductor switch, commonly known as a Triac comprises a semiconductor body having at least five superposed zones alternating in conductivity types, the three inner zones forming the basic interior structure and the outer zones, each of different conductivity types, located at the opposite end faces of the semiconductor body forming the emitter or anode boundary zones respectively, and having a main electrode in ohmic contact therewith. One end face also includes first and second control zones of different conductivity types spaced laterally from the outer zones of different conductivity types at that end and in ohmic contact with a control electrode common to both control zones.