Physics > Semi-conductor Devices and Electronics > 9.0 Light emitting diode (LED)
Semi-conductor Devices and Electronics
1.0 Introduction
1.1 Classification of solids on the basis of their conductivity
1.2 Band theory of solids
1.3 Classification of solids on the basis of band theory
2.0 Types of semiconductor
3.0 Mass action law
4.0 Electrical conductivity in semiconductor
5.0 $p-n$ junction
5.1 Depletion region
5.2 Forward biasing of a $p-n$ junction
5.3 Reverse biasing of a $p-n$ junction
6.0 Breakdown voltage
7.0 $I-V$ characteristics of a $p-n$ junction
8.0 Rectifier
8.1 Half wave rectifier
8.2 Full wave rectifier
8.3 Ripple frequency
8.4 Ripple factor
8.5 Ripple efficiency $\left( \eta \right)$
8.6 Form factor
9.0 Light emitting diode (LED)
10.0 Zener diode
11.0 Transistor
12.0 Boolean identities
13.0 Logic gates
14.0 De Morgan's theorem
9.1 Photo diode
1.2 Band theory of solids
1.3 Classification of solids on the basis of band theory
5.2 Forward biasing of a $p-n$ junction
5.3 Reverse biasing of a $p-n$ junction
8.2 Full wave rectifier
8.3 Ripple frequency
8.4 Ripple factor
8.5 Ripple efficiency $\left( \eta \right)$
8.6 Form factor
Photo diode is used to detect light.
Note:
- Photo diode is a special type $p-n$ junction diode fabricated with a transparent window to allow light to fall on the diode.
- Photo diode is operated under reverse bias.
- When it is illuminated with light of photon energy greater than the energy gap of the semiconductor, electron-hole pairs are generated in near depletion region.
- Photo diode has to be fast, which means low capacitance, which means small area of the junction.
- The symbol of a photo diode is shown in the figure below,
