Which VVC diode consists of graded doping profile & functionally known as a 'snap diode?

Which VVC diode consists of graded doping profile & functionally known as a 'snap diode?

a. Varactor Diode
b. Tunnel Diode
c. Gunn Diode
d. Step Recovery Diode

Correct Answer:d. Step Recovery Diode

Explanation:

Step Recovery Diode belongs to the category of Voltage Variable Capacitor (VVC) diode whose doping density reduces in the vicinity of junction.
This gives rise to the generation of strong electric field on both sides of the junction.

As usual, this diode also conducts in forward direcction similar to other diodes.Thus, the reverse current flows during the reverse half-cycle because of draining of the stored charge and consequently the current suddenly falls to zero.

This kind of operational strategy resemble like a diode that has snapped open suddenly during an inceptional portion of reverse cycle.

As a result, step recovery diode is also known as 'Snap diode'. Also, the property of diode to exhibit sudden recovery from reverse ON current to reverse OFF current nominates it as a 'Step Recovery Diode'.