Diode
Presented
By
Bijoy Kumar Pondit
What is a Diode?
Two-terminal electronic component that only conducts current in one direction .
An ideal diode will have zero resistance in one direction.
Infinite resistance in the reverse direction.
Like a one valve for an electrical circuit.
Diode Symbol
The arrowhead points in the direction of conventional current
flow in the forward biased condition.
The anode is connected to the p side .
The cathode is connected to the n side.
Working Principle of Diode
An n-type semiconductor a high concentration of free electrons and a low
concentration of holes.
A p-type semiconductor has a high concentration of holes and a low concentration of
free electrons.
Unbiased Diode
When one n-type region and one p-type region come in contact.
The holes start diffusing from the p-type
region to the n-type region.
Free electrons start diffusing from the
n-type region to the p-type region.
The layers of uncovered positive ions and
uncovered negative ions form a region in the
middle of the diode.
This region is called the depletion
region.
There is no more diffusion of charge
carriers from one side to another.
Forward Biased Diode
Externally applied forward voltage.
Becomes more than the forward barrier
potential.
The free majority charge carriers start
crossing the barrier.
Contribute the forward diode current.
Reverse Biased Diode
We connect the negative terminal of
the voltage source to the p-type side
and the positive terminal of the voltage
source to the n-type side of the diode.
The holes in the p-type region would
be shifted more away from the junction
leaving more uncovered negative ions
at the junction.
The free electrons in the n-type region
would be shifted more away from the
junction towards the positive terminal of
the voltage source leaving more
uncovered positive ions in the junction.
The characteristic curve of a junction diode
Types of Diode
Zener diode
PN junction diode
Tunnel diode
Varactor diode
Schottky diode
Photodiode
PIN diode
Laser diode
Avalanche diode
Light emitting diode
Applications of Diodes
Diode as a Rectifier
DC output
Diodes in Reverse Current Protection
Thanks to all
