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.