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CONTENTS

I. Introduction

II. Semiconductors

III. Germanium

IV. Silicon

V. Gallium- Arsenide

VI. Other Semiconductors

VII. References

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INTRODUCTION

Material

Conductor InsulatorSemiconductors

valence electrons areloosely bounded

large number of free

electrons at 300K

valence electrons aretightly bounded

very few free electrons at

300K

Elements Compound

Si, Ge GaAs, InP, SiC, CdTe,

AlGaAs, InGaAsP

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PERIODIC-TABLE

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ENERGYBANDDIAGRAM

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GERMANIUM

Atomic No. = 32Band Energy = 0.67ev

Resistivity = 102-cm

Intrinsic Carriers = 2.5x

1013

/ cm3

Relative Mobility =

3900 cm3 / V.s

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GERMANIUM

First Transistor Made from Ge,

discovered by Bardeen, Brattain

and Shockley at Bell Labs in 1947

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APPLICATIONSOFGERMANIUM

Used in early radar detection diodes and first transistors;requires lower purity than silicon.

A substrate for high-efficiency multijunction photovoltaic cells.

High-purity crystals used for gamma spectroscopy.

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SILICON

Atomic No. 14Band Energy = 1.12ev

Resistivity = 105-cm

Intrinsic Carriers = 1.5x

10

10

/ cm

3

Relative Mobility =

1500 cm3 / V.s

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ADVANTAGESOFSILICON

Stable and strong material & crystal structure likediamond.

higher operating temperature (125-175 C vs. ~85 C) and

thus become intrinsic at higher temp.

Si is cheap and abundant.Silicon has stable reverse breakdown voltage than

germanium and also the knee voltage is higher.

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GALLIUM-ARSENIDE

Atomic No. :-Ga = 31, As = 33

Band Energy = 1.43 ev

Resistivity = 109-cm

Intrinsic Carriers =1.7x1006/ cm3

Relative Mobility =

8500 cm3 / V.s

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APPLICATIONOFGALLIUM-ARSENIDE

second most common in use after silicon.commonly used as substrate for other III-V

semiconductors, e.g. InGaAs and GaInNAs.

Brittle.

P-type CMOS transistors unfeasible.Used for near-IR LEDs, fast electronics, and high-

efficiency solar cells.

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OTHERSEMICONDUCTORS

Material Formula BandGap(ev)

Application

Indium

phosphide

InP 1.35 used in high-power and high-frequency

applications.

Silicon

carbide,

SiC 2.3 - 3 LEDs, power electronics

Aluminium

gallium

arsenide

AlGaAs 1.42

2.16

Solar Cells, Can be used for infrared laser

diodes

Indium

GalliumNitride

InGaN 2 3.4 possible use in satellite solar cells, High

heat capacity

Silicon

GermaniumSiGe 0.67

1.11

adjustable band gap

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REFRENCES

http://www.engr.sjsu.edu/WofMatE/Semiconductors.htm

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/sili.html

http://www.edaboard.com/thread134217.html

http://en.wikipedia.org/wiki/Semiconductor

http://en.wikipedia.org/wiki/List_of_semiconductor_materials

http://www.youtube.com/watch?v=03j4ZvQCKWY

Book:-Electronic Devices And Circuit Theory by Robert L. Boylestad, Louis Nashelsky

http://www.engr.sjsu.edu/WofMatE/Semiconductors.htmhttp://hyperphysics.phy-astr.gsu.edu/hbase/solids/sili.htmlhttp://www.edaboard.com/thread134217.htmlhttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/List_of_semiconductor_materialshttp://www.youtube.com/watch?v=03j4ZvQCKWYhttp://www.youtube.com/watch?v=03j4ZvQCKWYhttp://en.wikipedia.org/wiki/List_of_semiconductor_materialshttp://en.wikipedia.org/wiki/Semiconductorhttp://www.edaboard.com/thread134217.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/solids/sili.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/solids/sili.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/solids/sili.htmlhttp://www.engr.sjsu.edu/WofMatE/Semiconductors.htm

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QUESTIONS

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