Zener diode

Zener diode

Zener diode as a voltage regulator
Zener diode working
Zener diode circuit
Zener diode difination

Everyone this is my new post! 
And the topic for today is Zener diode as voltage regulator.

We will learning the concept of avalanche breakdown and Zener breakdown

Lets start with the topic

Diodes which have adequate power dissipation capabilities to operate in the breakdown region are commonly called zener diodes.
   
Avalanche multiplication and zener breakdown are two process, which produce the breakdown region in the reverse bias.

Avalanche Multiplication
During reverse bias the depletion region widens in ordinary diode. Carriers which are generated thermally will get sufficient energy from applied potential. The crystal atom are collided by these carriers and imparts energy to disturb the covalent bond. Because of these actions a new electron hole pair is generated and these electrons also gets energy from applied field. Through continues collision by these electron with another atom more number of electron hole pair is generated. This action continuous and produce additional carriers. This cumulative process is known as avalanche multiplication. This results in large reverse current and diode will be in breakdown region.

Zener breakdown
When a diode is heavily doped, there will be a narrow depletion layer due to this the electric field across depletion layer will be very high. Because of the presence of this electric field across the junction a strong force may be applied on bound electrons by the field to tear it from covalent bonding. The new hole pair created raises the reverse current. This process is known as zener breakdown

Zener diode 
     A heavily doped diode, which has a sharp breakdown voltage is known as a zener diode. Fig shows the symbol of zener diode.

symbol



 Due to heavy doping the electric field in the junction increases during reverse bias. Hence covalent bonds breaks producing a large number of electron hole combinations. This in turn increases reverse current. The diode possess some resistance called zener dynamic resistance. 


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