The document discusses various semiconductor devices including p-n junction diodes, rectifiers, special purpose diodes, bipolar junction transistors, and logic gates. It explains the working principles and applications of these devices. Rectification using half wave and full wave diode rectifiers is described to convert AC to DC. Special diodes like photodiodes, solar cells and LEDs are also covered. The common emitter configuration of a BJT and its use as an amplifier is explained. Finally, logic gates like NOT, OR, AND, NAND, NOR and XOR are defined along with their working principles.

1. Std : 12th Year : 2020-21
Subject : PHYSICS
Chapter 16: SEMICONDUCTOR DEVICES
CLASSXII
MAHARASHTRA STATE BOARD

2. Can yourecall?
• What is a p-n junction diode?
A p-n junction diode is two-terminal or
two-electrode semiconductor device.
• What is breakdown voltage and knee voltage?
The forward voltage at which the current through
the junction starts increasing rapidly, is called the
knee voltage or cut-in voltage. The reverse voltage
at which P-N junction of a diode breaks down with
sudden rise in reverse current is known as break
down voltage.
• What is a forward and reverse biased diode?
In a standard diode, forward biasing occurs when the voltage
across a diode permits the natural flow of current, whereas
reverse biasing denotes a voltage across the diode in the
opposite direction.

3. 16.1 Introduction
• The AC voltage shown as a sinusoidal wave from the secondary of the
transformer is converted into a DC voltage by a diode rectifier. This is
shown next as a pulsating wave (b).
• The output of the rectifier contains some AC component. This AC
component in the DC output of a rectifier is called ripple.
• It is removed by using a filter circuit. The output of the filter circuit is
almost a pure DC.

4. 16.2 p-n Junction Diode as a Rectifier
• The conversion of AC voltage into a DC voltage is called rectification.
• An electronic circuit which rectifies AC voltage is called rectifier.
• There are two types of rectifier circuits, 1) half wave rectifier and 2) full wave rectifier.
16.2.1 Half Wave Rectifier 16.2.2 Full Wave Rectifier

5. 16.2 p-n Junction Diode as a Rectifier

6. 16.2 p-n Junction Diode as a Rectifier
16.2.3 Ripple Factor
16.2.4 Filter Circuits
A filter circuit is a circuit which removes the AC component or the
ripple from a rectifier output and allows only the DC component.
A capacitor filter:

7. 16.3 Special Purpose Junction Diodes
16.3.2 Photo Diode
Working Principle of Photodiode

8. 16.3 Special Purpose Junction Diodes:
16.3.3 Solar Cell or Photovoltaic Cell
Two major types of devices converting solar energy in
usable form are, a) Photo thermal devices
b) Photo voltaic devices
Structure of a Solar Cell:
Working of Solar cell: V-I Characteristic of solar Cell or
Photovoltaic cell:

9. 16.3 Special Purpose Junction Diodes:
16.3.3 Solar Cell or Photovoltaic Cell
Criteria for selection of material for solar cell:
1) Its band gap should be between 1.0 eV to 1.8 eV.
2) It should have high optical absorption (conversion of light into electrical energy).
3) It should have good electrical conductivity.
4) Material should be easily available.

10. 16.3 Special Purpose Junction Diodes:
16.3.4 Light Emitting Diode / LED
Working of LED I-V Characteristics Light Emitting Diode

11. 16.3 Special Purpose Junction Diodes:
16.3.4 Light Emitting Diode / LED
Applications of Light Emitting Diode
There are many applications of LED and some of them are explained below.
• LED is used as a bulb in the homes and industries.
• The light-emitting diodes are used in motorcycles and cars.
• These are used in mobile phones to display the message.
• At the traffic light signals led’s are used.

12. 16.4 Bipolar Junction Transistor (BJT):
Working of a p-n-p transistor:

13. 16.4 Bipolar Junction Transistor (BJT):
Transistor configuration: The possible configurations of transistor in a circuit are,
(a) Common Emitter, CE (b) Common Base, CB and (c) Common Collector, CC.
16.4.1 The Common Emitter (CE) Configuration

14. 16.4 Bipolar Junction Transistor (BJT):
16.4.2 The Common Emitter (CE) Configuration 16.4.3 Transistor as an Amplifier
Working of the Amplifier

15. 16.5 Logic Gates
• Continuously varying signal (voltage or current) are is called analog signals.
• A signal (voltage or current) which can have only two discrete values is
called a digital signal.
• An electronic circuit that handles only a digital signal is called a digital
circuit.
• The branch of electronics which deals with digital circuits is called digital
electronics.
• A digital circuit with one or more input signals but only one output signal
is called a logic gate.
16.5.1 NOT Gate 16.5.2 OR Gate:

16. 16.5 Logic Gates
16.5.3 AND Gate: 16.5.4 NAND Gate:
16.5.5 NOR Gate: 16.5.6 Exclusive OR/ X-OR Gate :

17. The Principle of Diode
https://javalab.org/en/led_en/
p-n Junction Diode
http://amrita.olabs.edu.in/?sub=1&brch=6&sim=233&cnt=4
Transistor application circuit
https://javalab.org/en/transistor_2_en/
Bipolar Junction Transistor (BJT):
http://amrita.olabs.edu.in/?sub=1&brch=6&sim=234&cnt=4

18. Thank You