Shockley Diode

Shockley Diode
A Shockley diode is a four-layer, PNPN semiconductor device that acts as a voltage-triggered switch and is the basis for other thyristors. It remains in its off state until the voltage across it exceeds a specific "breakover voltage," at which point it conducts and latches on. To turn it off, the current flowing through it must be reduced below a low-current "dropout" threshold. 
Key characteristics
• Structure: Consists of four alternating layers of P-type and N-type semiconductor material, forming three P-N junctions.
• Function: It is a two-terminal device with no gate, functioning similarly to a thyristor. It acts like a closed switch once triggered.
• Triggering: It turns on when the forward voltage across the anode and cathode exceeds the breakover voltage, or if the rate of voltage rise is too high.
• Turning off: It turns off when the current flowing through it drops below the holding current (dropout threshold).
• Application: It is historically significant and forms the basis for more complex thyristor devices like SCRs and TRIACs. It is also used in applications like relaxation oscillators.
• Availability: It is not commonly available for purchase in modern electronics, but its principles are fundamental to other semiconductor devices. 
This model shows how to model a simple Shockley diode— a four-layer PNPN semiconductor device. The Shockley diode is also named as thyristor. In this model, the Analytic Doping Model node is utilized to define the doping profiles for each domain. A time-dependent study is employed to calculate the I–V characteristics of the Shockley diode.

The Shockley diode (named after William Shockley) is a four-layer semiconductor diode. It is a PNPN diode with alternating layers of P-type and N-type material. It is equivalent to a thyristor with a disconnected gate. Shockley diodes were manufactured and marketed by Shockley Semiconductor Laboratory in the late 1950s. The Shockley diode has a negative resistance characteristic.[1] It was largely superseded by the DIAC.
Unlike other semiconductor diodes, the Shockley diode has more than one p–n junction. The construction includes four sections of semiconductors placed alternately between the anode and cathode in the pattern of PNPN. Though it has multiple junctions, it is termed a diode for being a two-terminal device.
The Shockley diode remains in an OFF state, with a very high resistance, until a voltage greater than the trigger voltage is applied across its terminals.


* Study My Work For Knowledge Synergy*

** Mahsa Hassankashi **
Youtube: @MahsaHassankashi
Git Repository: @MahsaScript

   • Shockley Diode