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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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