Abstract: A first rectifying contact portion of a semiconductor device such as a Zener diode has a small area in order to attain a hard breakdown characteristic and a low noise characteristic. When a predetermined current which is not greater than the maximum allowable instantaneous value of non-D.C. currents flows through the first rectifying contact portion, a second rectifying contact portion which has a large area starts breakdown due to a voltage drop across a resistance component connected in series with the first rectifying contact portion and a breakdown voltage of the first rectifying contact portion.Owing to the fact that current is dispersed to the first rectifying contact portion and the second rectifying contact portion, a semiconductor device such as a Zener diode exhibiting a high endurance characteristic against surge voltages can be provided.

Abstract: This invention is directed to a punch-through reference diode comprising a first semiconductor region of a first conductivity type which is formed within a semiconductor body; a second semiconductor region of a second conductivity type which is formed within the semiconductor body, the second semiconductor region adjoining the first semiconductor region and defining a first PN-junction with the first semiconductor region; and a third semiconductor region of the first conductivity type which is formed within the semiconductor body, the third semiconductor region adjoining the second semiconductor region and defining a second PN-junction with the second semiconductor region, whereby the second semiconductor region is located between the first PN-junction and the second PN-junction.