TUNNEL DIODE final

8/7/2019 TUNNEL DIODE final

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TUNNEL DIODE

A PRESENTATION OF GROUP k


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PRESENTED BY:

PARAMITA DAS

ARUP KUMAR KUMAR

ARITRA KUMAR GHOSHANKUR DAS

ARIJIT MAJUMDER

NILANJAN DAS UKIL


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CONTENTS:CONTENTS:

What is tunnel diode?

Invention

Description

Some scematic diagrams Types of tunnel diodes

Reverse bias operation

Forward bias operation

Characteristic curveApplications

Bibliography


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WHAT IS TUNNEL DIODE?

A TUNNEL DIODE or Esaki Diode is aA TUNNEL DIODE or Esaki Diode is aA TUNNEL DIODE or Esaki Diode is atype of semiconductor diode which istype of semiconductor diode which istype of semiconductor diode which iscapable of very fast operation, well intocapable of very fast operation, well intocapable of very fast operation, well intothe microwave frequency region, bythe microwave frequency region, bythe microwave frequency region, by

using quantum mechanical effects.using quantum mechanical effects.using quantum mechanical effects.


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INVENTION:

IT WAS INVENTED INAUGUST 1957 BYIT WAS INVENTED INAUGUST 1957 BY

LEO ESAKI WHEN HE WASWITH TOKYOLEO ESAKI WHEN HE WASWITH TOKYO

TSUSHIN KOGYO (NOW KNOWNASSONY),TSUSHIN KOGYO (NOW KNOWNASSONY),

WHO IN 1973RECEIVED THE NOBELWHO IN 1973RECEIVED THE NOBEL

PRIZE INPHYSICSFORDISCOVERING THEPRIZE INPHYSICSFORDISCOVERING THE

ELECTRON TUNNELING EFFECT USED INELECTRON TUNNELING EFFECT USED IN

THESE DIODES.THESE DIODES.


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DESCRIPTION:

These diodes have aThese diodes have aheavily doped pheavily doped p--nnjunction only some 10 nmjunction only some 10 nm

(100 ) wide. The heavy(100 ) wide. The heavydoping results in adoping results in abroken bandgap, wherebroken bandgap, whereconduction band electronconduction band electronstates on the nstates on the n--side areside are

more or less aligned withmore or less aligned withvalence band hole statesvalence band hole stateson the pon the p--side.side.


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CONTD

Tunnel diodes were manufactured by SONYTunnel diodes were manufactured by SONYfor the first time in 1957 followed byfor the first time in 1957 followed byGeneral Electric and other companies fromGeneral Electric and other companies from

about 1960, and are still made in lowabout 1960, and are still made in lowvolume today. Tunnel diodes are usuallyvolume today. Tunnel diodes are usuallymade from germanium, but can also bemade from germanium, but can also bemade in gallium arsenide and siliconmade in gallium arsenide and siliconmaterials. They can be used as oscillators,materials. They can be used as oscillators,amplifiers, frequency converters andamplifiers, frequency converters anddetectors.detectors.


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Some SchematicDiagramsSome SchematicDiagrams


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Types of tunnel diodes:

commercial tunnel diodes

broadband tunnel diodes

planar tunnel diodes

verticalsilicon tunnel diodes

ACP tunnel diodes

hybrid tunnel diodes

resonance tunnel diodes silicon/silicon-germaniumresonant interband

tunnel diodes


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Reverse bias operationReverse bias operation

1.1. When used in the reverse direction they areWhen used in the reverse direction they arecalled back diodes and can act as fast rectifierscalled back diodes and can act as fast rectifierswith zero offset voltage and extreme linearity forwith zero offset voltage and extreme linearity for

power signals (they have an accurate square lawpower signals (they have an accurate square lawcharacteristic in the reverse direction).characteristic in the reverse direction).

2.2. Under reverse bias filled states on the pUnder reverse bias filled states on the p--sidesidebecome increasingly aligned with empty statesbecome increasingly aligned with empty stateson the non the n--side and electrons now tunnel throughside and electrons now tunnel through

the pn junction barrier in reverse directionthe pn junction barrier in reverse direction iithis is the Zener effect that also occurs in zenerthis is the Zener effect that also occurs in zenerdiodes.diodes.


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Forward bias operationForward bias operation

under normal forward bias operation, as voltage beginsunder normal forward bias operation, as voltage beginsto increase, electrons at first tunnel through the veryto increase, electrons at first tunnel through the very

narrow pnarrow p--n junction barrier because filled electronn junction barrier because filled electron

states in the conduction band on the nstates in the conduction band on the n--side become alignedside become aligned

with empty valence band hole states on the pwith empty valence band hole states on the p--side of the pnside of the pn

junction.junction.

As voltage increases further these states become moreAs voltage increases further these states become more

misaligned and the current dropsmisaligned and the current drops this is called negativethis is called negative

resistance, because current decreases with increasingresistance, because current decreases with increasing

voltage.voltage.

As voltage increases yet further, the diode begins toAs voltage increases yet further, the diode begins to

operate as a normal diode, where electrons travel byoperate as a normal diode, where electrons travel by

conduction across the pn junction, and no longer byconduction across the pn junction, and no longer by

tunneling through the pn junction barrier. Thus the mosttunneling through the pn junction barrier. Thus the most

important operating region for a tunnel diode is theimportant operating region for a tunnel diode is the

negative resistance region.negative resistance region.


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Characteristic CurveCharacteristic Curve

The negative resistance region is the mostimportant and most widely used

characteristic of the tunnel diode. A

tunnel diode biased to operate in the

negative resistance region can be used as

either an oscillator or an amplifier in awide range of frequencies and

applications. Very high frequency

applications using the tunnel diode are

possible because the tunneling action

occurs so rapidly that there is no transit

time effect and therefore no signaldistortion. Tunnel diodes are also used

extensively in high-speed switching

circuits because of the speed of the

tunneling action.


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Contd


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Applications:

They are used in:

low power amplifiers

microwave and RF power monitors

high-frequency triggers ALC loops

zero bias detectors

ACP tunnel diode circuits

Space applications like amplifiers for satellitecommunications.


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BIBLIOGRAPHY

WWW.WIKIPEDIA.ORG

www.tpub.com

www.partminer.com

ELECTRONICDEVICES ANDCIRCUIT

THEORY BYR.L.BOYLESTEAD AND

L.NASHELSKY

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TUNNEL DIODE final