Abstract: In a breakover type surge protection device utilizing punch-through that comprises a second semiconductor region forming a first pn junction with a first semiconductor region, a third semiconductor region forming a second pn junction with the second semiconductor region and a fourth semiconductor region forming a third pn junction with the first semiconductor region at a place apart from the second semiconductor region, the second semiconductor region is constituted of a punch-through suppression region portion disposed to cover the corners of the third semiconductor region and a punch-through generation region portion disposed at a place where its thickness can be made uniform. Fabricating surge protection devices according to this configuration reduces variation among their breakover currents and hold currents and increases their surge absorption capacity.

Abstract: A surge protection device for absorbing surges of either polarity has a second region forming a first pn junction with a first region, a third region capable of injecting first minority carriers into the second region, a fourth region forming a second pn junction with the first region and a fifth region capable of injecting second minority carriers into the fourth region. The surfaces of the fourth region and the fifth region and a first Schottky junction with respect to the first region are in mutual electrical connection with a first ohmic electrode, while the surfaces of the second region and the third region and a second Schottky junction with respect to the first region are in mutual electrical connection with a second ohmic electrode.

Abstract: A vertical type surge protection device for absorbing surges of either polarity has a second region forming a first pn junction with a first region, a third region forming a first minority carrier injection junction with respect to the second region, a fourth region forming a second pn junction with the first region and a fifth region forming a second minority carrier injection junction with the fourth region. When the absolute value of a surge voltage applied across the device exceeds the breakdown voltage, either the one of the first and second pn junctions that is reverse biased owing to the surge polarity breaks down or punch-through occurs between the first and third regions or between the first and fifth regions, whereafter breakover ensues as a result of positive feedback.