P-N JUNCTION

A very warm welcome to everyone in this very cool day. In the previous session we have started the basics of electronics , in that we have stated that semiconductor devices plays a major role in electronics concepts. By considering that today we are going to discuss about the concept of P-N junction diode

Before going to the topic ,let us see some important terms regarding semi conductors.

1.Doping :
Addition of impurity atoms to intrinsic semiconductor crystal is called doping and the impurity used is called dopant.

2.Diffusion : The process of doping a semiconductor with impurities is called diffusion.

3.Donor : Any pentavalent impurity used as dopant to produce N-type semiconductor is called donor.
Arsenic,antimomy etc.,

4.Acceptor : Any trivalent impurity used as dopant to produce P-type semiconductor is called acceptor.

P-N junction :
Basically every semiconductor material has majority and minority carriers.

        a.P-type material :
             Majority carriers - holes.
             Minority carriers - electrons.

          b.N-type material :
              Majority carries - electrons.
              Minority carriers - holes.

P-N junction represents two blocks of semiconductor materials , one p-type and one n- type material. On the formation of P-N junction some of the holes from p-type material tend to diffuse across the boundary into n-type material and some of the free electrons similarly diffuse into p-type material.

This is happend because of concentration of holes is higher on p-side than that of n- side and vice-versa.This process is called diffusion.

The region around the junction is completely ionised .As there are no free electrons on N-side and there are no holes on p-side . Since the region around the junction is depleted of mobile charges it is called the depletion region , space charge region or the transition region.
The thickness of the depletion region is of the order of one micron.

Today I have provided some concept regarding P-N junction in the next post I will describe about different types of biasing and characteristics....

If you want to be powerful, educate yourself....
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