Characteristics of a PNPN switch with an AL-SI Schottky clamp diode

The compatibility of Schottky diodes with planar integrated circuit technology has led recently to their widespread use as clamping diodes for npn switching transistors. The authors have extended this idea to the fabrication of pnpn switches and studied the transient and d-c characteristics of such a structure. In the device fabricated, an Al-Si Schottky diode is connected between the two bases with the cathode of the diode common with the base of a lateral pnp transistor. By preventing saturation from occurring in either transistor, the Schottky diode causes the pnpn switch to have much shorter recovery times (measured in the order of tens of nanoseconds) than conventional unclamped pnpn switches. Various methods of turn-off and terminal bias affect the values of the recovery time as well as other important switching times.