Semiconductor Materials
Submitted by: Arabi RadwanSubmitted by: karim ahmed abu amo
Semiconductors
• Introduction• Definition & Function• Formation or production• Crystal structure• Application
Introduction
Conductor: allow current to flow because they are made of materials with abundant of free electron.
Insulator: restrict current to flow because they have small numbers of free electron.
Semiconductor :have enough electrons to allow some current to flow but not enogh to allow so easily.
Electrical conduction is the result of electron motion within each band
For a conductor, conduction bands and valence bands are not separated and there is therefore no energy gap. The conduction band is then partially occupied (even at low temperatures), resulting in a “high” electrical conductivity.
What is a Semiconductor A semiconductor is a material that
has intermediate conductivity between a conductor and an insulator
Also called "III-V" materials since semiconductor elements are in groups III and V of the periodic table of chemical elements.
Examples are silicon (14Si), germanium(32Ge)
Doping• Doping : is the addition of
minute quantities of non-silicon material to semiconductor.
• This added material changes the number of vailable free electron .
• Doping process produces two groups of semiconductors: the negative charge conductor (n-type) and the positive charge conductor (p-type)
N-type and P-type• As (phosphorus), a Group V
element, introduces conduction electrons and creates N-type silicon (called a Donor).
• B (Boron), a Group III element, introduces holes and creates P-type silicon, and is called an acceptor.
Production-
Examples
Diode: A one way valve
Allow current to flow in only one direction
Transistor: Electronic Switch
Types of Diodes
Power diode (500-1000 Volt) Used in power circuits
Zener Diode Allow current to flow in
reverse biased(only at specific volt)
Light emitting diode(LED) Used in automobile Required (1.5 -2 volt 30 mA)
Diode
Schematic symbol
How it works
Anode Cathode
Reversing polarityof the power source
Applications
• Power diode• (AC to DC converter)
half wave rectifier
Full wave rectifier(power supply)
Function Semiconductors act as an electrical conductor
or insulator depending on chemical alteration It also control and amplify current or volt
using a small voltage or current. Examples: Diode: allow or restrict current to flow Transistors: Amplifying
Automotive alternator
• Battery charging• Six diodes
(rectifier Bridge)
Transistors
Analogy
• Use a low current to control a higher current
• Act as a switch or gate for electronic circuit.
• Used as an amplifier
Amplification
Applications
Diode
Schematic symbol
How it works
Anode Cathode
Functions
Semiconductor devices control and amplify because a small voltage or current, allows the semiconductor to pass or block electrical current.
Devices can be fabricated with other capabilities such as passing electric current in only one direction, emitting light, mixing and transforming signals, etc.
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