Zener diode

Hello friends..welcome back to this blog.  Today we are here to present a new concept in electronics. Actually in the last topic we discussed about P-N junction diode and its V-I characteristics.We hope  from the last topic gave the knowledge and  guidance to the working of P-N junction diode and its characteristics. There are some special diodes and functioning in the diodes.Today's topic is about ZENER diode. So lets go through the topic.

Zener-diode

We all know that from P-N junction as the voltage is increased in forward bias the maximum current flows and in reverse bias a small fraction of  current flows after the breakdown voltage, so in order to use the diode in reverse bias we have a special diode i.e, ZENER diode.

 Zener diode means a form of semiconductor diode in which at a critical reverse voltage large current can flow. Zener diode is operated in reverse bias only. A zener diode is heavily doped than ordinary diode.When reverse voltage reaches breakdown voltage in normal P-N junction diode, the current through the diode and the power dissipated at the junction will be high. Such operation damages the diode.With adequate power dissipation capability to operate in breakdown region a special diode is designed which is called "Zener diode".    

Symbol of zener diode:

Zener diode is always reverse connected.When forward biased its characteristics are just like normal diode.It has sharp break down voltage called breakdown voltage.

Explanation: 

It is mainly a special property of the diode rather than any special type of equipment. The person named clearance Zener invented this property of the diode so it is named as "Zener diode". The special property of the diode is that there will be a breakdown in the circuit if the voltage applied across a reversely biased circuit.

a)V-I Characteristics of zener diode

• From the V-I characteristics of Zener diode it is found that the operation of zener diode is same as P-N junction diode in forward bias.
• Under reverse bias condition its working is changed, here breakdown of junction occurs and breakdown is sharp. The break down voltages are dependent on amount of doping.

There are two types of breakdowns

1.Zener breakdown:

                                            In zener breakdown due to heavy doping, direct rupture of covalent bond takes place because of strong electric field. Hence new electron-hole pairs are created which increases the reverse current in reverse bias.

2.Avalanche breakdown:

                                            In avalanche breakdown if reverse bias voltage increases the charge carriers acquire large amount of kinetic energy and their velocity also increases. These carriers(electrons) disturb the covalent bond by colliding with immovable ions and create new electron hole pairs. 

This was all about Zener diode.From next post we will discuss about applications of zener diodes.. so stay tuned for more updates and moreover thanks for visiting us....please follow and share us for more better people to stay in....