Shockley diode
The four-layer diode, also referred to as or as Dinistor Shockley diode ( after physicist William B. Shockley ) is a silicon semiconductor device having four semiconductor regions. The first four-layer diodes were produced in the late 1950s from Shockley Semiconductor Laboratory, and were among the first made of silicon semiconductor devices. It is now superseded by other semiconductor devices and has no economic importance.
The Shockley diode is not to be confused with the Schottky diode.
Function
The function of the four-layer diode is similar to a thyristor with gate not connected. The device consists of four differently doped semiconductor layers and three pn-junctions, as shown in the figure under a. The equivalent circuit in b. shown, comprises two bipolar transistors, each with an NPN and PNP transistor. The circuit symbol is under c. mapped. The two terminals of the four-layer diode hot anode and cathode.
At a certain voltage corresponding polarity at the terminals exceeded ignition occurs: The four-layer diode is low. This condition exists as long as a certain holding current is reached. Thereafter, the device tilts back into the high-impedance output state. This function corresponds to the so-called overhead ignition (English breakover ) a thyristor. Thyristors, which are specially designed for the overhead ignition are also referred to as Dynistor and see the power electronics application. From their behavior is similar to the four-layer diode designed for AC voltage multilayer diodes ( diac ).
Low-power, four -layer diodes as switching devices used mainly for the control of thyristors.
Characteristic and typical values
( Zener voltage UZ)
Alternative name and graphic symbol
In the literature, other names and symbols for the four-layer diode are used, some of which are also used for diac:
- Thyristor diode
- Trigger diode
- Breakover diode
- 4-layer diode transistor
- PNPN diode