Diode Notes BSCS In Basic Electronics notes

Diode Notes BSCS In Basic Electronics notes

1. Basic Electronics
Lecture 4
•What is Diode?
•What is P-N Junction?
•Formation of Diffussion process
•Formation of Dipletion Layer

2. Diode
•Diode is an electronic device with two element namely
Anode and Cathode

3. P-N Junction
•An P-type Semiconductor and N-type Semiconductor are
joined together with the help of a fabrication technique to form
a P-N Junction
P N
Majority
charge
Minority
charge
Majority
charge
Minority
charge
Junction

4. P-N Junction
Diode symbol
P N

5. Formation of diffusion process
P N

6. Formation of diffusion process
•In order to create p-n junction diode, we have to take one P-type and
one N-type semiconductor and joint it.
•The tendency of electrons is to move towards the positive side
•In P-type semiconductor majority charge carriers are holes and
electrons are the minority charge carriers
•In N-type semiconductor electrons are the majority charge carriers
and holes are the minority charge carriers
•The electrons will move towards the hole and diffuses itself while
the holes will move towards the electrons and diffuses itself. The
process is called diffusion process.

7. Formation of Depletion Layer
P N
+ -
-
-
-
+
+
+
-ve
immobile
ions
+ve
immobile
ions
Depletion
Layer

8. Formation of Depletion Layer
•The free electrons from N-side will defuse into the P-side and
recombine the holes present there.
•Each electron will leave behind a positive immobile ion into the N-
side and each hole will defuses into the N-side will leave behind a
negative immobile ion
•Due to this recombination process, a large no.of positive ions
accumulate near the junction on the n-side and a large no.of negative
immobile ions will accumulate on the p-side near the junction
•The negatively charged ions on the p-side will start repuling the
electrons and after some time the diffusion will stop completely

9. Formation of Depletion Layer
•The p-n junction is in the state of equilibrium
•The shaded region on both sides of the junction contains only
immobile ions and no free charge carriers such as electrons or holes
•These region is called as depletion region
•The width of the depletion region is 0.5-1 mm (micrometer)