2. LIGHT EMITTING DIODE (LED)
• LED is a specially made forward biased PN
junction diode, which emits light when current
flows through it.
•CONSTRUCTION:
In this diode a P-type semi-
conductive material is deposited on the N-type
substrate layer by using diffusion method.
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4. Cont….
• The colour of the light emits from the diode
depending upon the type of material used, as
given below.
(1) GaAs : Infrared radiation
(2) GaP : Red or green light
(3) GaAsP : Red or yellow light
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6. Applications
• Used in ON and OFF indicators.
• Used in optical communications.
• Used in 7 segment and 14 segment displays.
• Used in optical switching applications.
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7. SEVEN SEGMENT LED DISPLAY
• It contains seven rectangular LEDs. Each LED is
called a segment because it forms a part of
the character being displayed.
• There are two possible connections in seven
segment displays. They are
1. common anode type(+ve)
2. common cathode type(GND)
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9. Comparison
S.
NO
LED LCD
1. • Consumes more power • Consumes less power
2. • Life time is more • Life time is low
3. • It emits light when energised • It will not emit or generate light.
4. • Red, Green, Yellow colour lights
are found, depends upon the
materials used.
• It is found only in monochrome in
nature.
2/25/2015 Prabhu Mike
10. SOLAR CELL
• A Solar cell or solar battery is also a PN
junction diode. It converts solar energy into
electrical energy. It is also called solar energy
converter.
• Construction:
A solar cell is made up of Germanium (Ge)
or Silicon (Si) materials.
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