Differences between Normal Diode Schottky diode zener diode and avalanche Diode

Differences between Normal Diode , Schottky

diode , zener diode and avalanche Diode.

A diode is a commonly used semiconductor , that acts as one way gate to the flow of electrons.

DIODE

i.e; it allows current to pass in one direction only.A pn-junction diode is formed by joining together n-type and p-type silicon.

When the anode and cathode of a pn-junction diode are connected to external voltage such that the potential at anode is higher than the potential at cathode , the diode is said to be forward biased. In a forward-biased diode current is allowed to flow through the device when the forward voltage is greater than forward breakdown voltage.forward voltage drop depends on the material in which it is constructed.

 When potential at anode is smaller than the potential at cathode, the diode is said to be reverse biased. In a reverse-biased diode current is blocked.

 Consider the below case

Switching cases

In first case the diode is forward biased. Since the voltage

Voltage@A>Voltage@B=Forward Biased

so what if the voltage at point B is increased to a level greater than point A.Diode will turn to Reverse Bias

voltage@A<Voltage@B=Reverse Bias

And if again the voltage at point B is reduced to a level less that voltage at point A.Diode will switch to Forward bias.

Voltage@A>Voltage@B=Forward Biased

so what if i increase the speed of this switching !!! 

A Normal diode will not be able to handle this high speed switching's and here comes the ROLE of Schottky Diodes.

Schottky Diode

Schottky diodes has higher switching rates ie they can turn ON and turn OFF very rapidly compared to other types of diodes.

it also have an advantage of having less forward breakdown voltage, normally in the range of .2 to .5V .Because of these features, they are widely used in high speed switching designs. especially in DC-DC converters.

As their switching speed is very high, Schottky diodes recover very fast when the current reverses, resulting in only a very small reverse current overshoot. 

Diode Symbols

	Forward voltage drop	Reverse Voltage drop
Normal Diode	.3 to 1.1V	50V+
Schottky Diodes	.2 to .4V	20V-40V
Zener Diodes	.3 to 1.1V	1.8V-200V

Zener diode is similar to normal diode but has a wide range of Reverse breakdown voltages . above that voltage zener will breakdown and starts conducting . it is widely used for protection by connecting it in reverse bias.

Zener diode

As the name says for zener diode in reverse bias zener breakdown is happening and in the case of Avalanche diode Avalanche breakdown is happening.

Avalanche diodes are also used for circuit protection. When the reverse bias voltage starts to increase, the diode intentionally starts an avalanche effect at a predetermined voltage. This causes the diode to start conducting current without damaging itself.

Avalanche type diodes can result in increased reliability in many applications, particularly those where voltage transients are expected.  

Due to its high speed and ability to withstand large numbers of transients, avalanche diodes are used to protect circuits against surges, lightning and other transients.  They are faster than MOV’s, zeners, and gas tubes.