about pnp or npn junction,Diode,Semiconductor

2. WE ARE:
1. Afnanul Hassan 161-15-7213
2. Khaled Akram Sany 161-15-7203
3. Shami Al Rahad 161-15-7349
4. Sohanur Rahman Sakib 161-15-7344
5. Nadeya Nusrat Ananna 161-15-6726

3. What Is LED (Light Emitting Diode)

5. P Type N Type

7. Any Semiconductor with impurity of
3 valance electrons, that makes a hole
(positive charge) in semiconductor is
called
p-type semiconductor.

9. Doping
+ =

11. Any Semiconductor with impurity of
5 valance electrons, that makes free
electron
(negative charge) in semiconductor is
called
n-type semiconductor.

13. Doping
+ =

16. Diode is usually made with pn
junction where pn junction
means the combination of p-type
& n-type semiconductor. That
conducts currents in forward bias
only.

21. Advantages:
Energy efficient source of light for short distances and small
areas. The typical LED requires only 30-60 mili watts to operate
Durable and shockproof unlike glass bulb lamp types
Directional nature is useful for some applications like reducing stray
light pollution on streetlights

22. Disadvantages:
May be unreliable in outside applications with great
variations in summer/winter temperatures.
Semiconductors are sensitive to being damaged by heat.
Rare earth metals used in LEDs are subject to price control
monopolies by certain nations.

23. ALLAH HaphejALLAH Haphej