Theory

Diode in Electronics

A diode, in electronics, is a two-terminal electronic component with asymmetric transfer characteristics, exhibiting low resistance to current flow in one direction and high resistance in the other. A semiconductor diode is the most common type of diode, consisting of a piece of semiconductor material with a p-n junction connected to two terminals.

A diode allows electric current to pass in the forward direction and blocks current in the reverse direction. The behavior of a diode in a circuit is described by its I-V characteristics. The shape of this curve is determined by the transport of charge carriers through the depletion layer at the p-n junction. When a p-n junction is first created, diffusion of holes and electrons occurs through the junction. As recombination proceeds, more ions are created at the junction, and a built-in potential develops in the depletion zone.

If a voltage of the same polarity as the built-in potential is applied across the junction, the depletion zone acts as an insulator, preventing significant current flow. This is known as the reverse bias phenomenon.

A Zener diode is a special-purpose diode designed to operate in the reverse breakdown region without damage. The I–V characteristics of a Zener diode consist of two regions: the forward bias region, which behaves like a normal diode, and the reverse bias region, where the diode enters breakdown and conducts significant current at a nearly constant voltage known as the Zener breakdown voltage.