What is working principle of PN Junction Diode?

Answer 1

Assuming that you are familiar with p-type

and n-type doped semiconductor materials,

we will consider silicon, in simple terms.

At the p-n junction area, electrons can more

easily pass from the n side to the p side.

This is due to the availibility of surplus electrons

in the crystal lattice structure of the n-type silicon.

Likewise a shortage of electrons in the crystal

lattice structure of the p-type, makes it a willing

acceptor of the electrons from the n-type at

the other side of the barrier.

This transfer through the junction requires a

specific force, in electrical terms what we call

voltage. For silicon 0.6 to 0.7 volts gets full and

safe current flow through the junction.

Less than about 0.6 V the current will be much less.

If the voltage polarity bias of the junction, is such

that the pressure is now trying to force electrons

from p to n, there will be only a tiny leakage current.

The result can be seen to be that a diode is a

one way valve for electrons. They can go

from n to p but not p to n.

Note that the arrow on the diode symbol is

pointing in the opposite direction to the

direction of electron movement. This symbol

was designed in the conventional current

only era, before we found out that current is

actually the movement of electrons.

Answer 2

A zener diode is made by using unusually high doping levels in both the p & n sides of the junction. As doping profiles cannot be changed after manufacture, it is not possible to convert a normal junction diode into a zener diode.

Answer 3

There are many different ways possible but the most common one used is diffusion. A semiconductor crystal having one type of doping is exposed at elevated temperature to the opposite type of dopant, which diffuses a short distance into the crystal as determined by the length of time of exposure and temperature. This creates the junction just below the crystal surface.

Answer 4

Actually that diode is made by is made by joining a P type semiconductor and an n type semiconductor together.