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SUPERCONDUCTINGTRANSISTOR

ARUNPRAKASHE7-B 7807

TKMCE

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contents

Introduction

Superconductivity

Josephsoneffect &tunneling

Nanowires

Superconductingtransistor

Application

SPD

Advantages & Disadvantages conclusions

References

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Introduction

Transistor-likeproperties

Atverylowtemperature

Act aspulse amplifier Doublelayertunnelingofquasi-

particles

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Superconductivity

Itistheoutstandingcharacteristicofcertainmaterialswhencooledextremelylowtemperaturestoconductdirectcurrentwithnoresistance andnolosses

Discoveredby Mr.Heike KamerlinghOnnesin 1911 in Hg at 4K

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Featuresofsuperconductors

Zerodcresistance

Magneticfluxlines areexpelledfrom

thematerial Smallchangeinthermalconductivity

andvolumeofmaterial

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Josephsoneffect andtunneling

Electronscanmovefromonesuperconductorto anotherthrough an

insulatinglayer

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Electricalmodelofnanowire

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Three-terminalsuperconducting

device Josephson junctiondevices

QUATRATRAN

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Application

Basicallyitisusedfortheamplificationofthepulsesgeneratedby SPD thatisthephotomultipliertube

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Photomultipliertube

Large amountofelectrons

aregeneratedfromthe

electrodewhen a photonstrikesonit

Biasedbelowits Tc

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PMT structure

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PMT operation

Photonstrikesonphotocathodelargeamountofelectrons areliberated and

currentsflowoccursbysecondaryemission

Dynodes are arrangedso astocatchalltheemittedelectrons

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Advantages

Largecurrentgain andbandwidth

Betterisolationbetweeninput and

output Highswitchingspeed

Lowpowerdissipation

Goodfrequencyresponses

Lownoise

Compactsize

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Disadvantages

The quasi-particlesinthedevicecannotrunperfectlythroughthecollector

Sufficientoutputsignalcannotbeobtained accordingtoinputsignal

Itisdifficulttomaintainthelow

temperature Thermalnoise also affectsthedevice

operation

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Conclusions

Devicewilloperate atlowtemperature

Similartonormaltransistor principleis quasi-particletrapping

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References

i. G. Ammendola et al., Non-equilibriumexperiments in LTS Josephson Double TunnelDevices,IEEE Trans. Appl. Supercond. vol. 9, no.2,PP 3974-3977,1999

ii. G. N. Goltsman, Picosecond superconductingsingle-photon optical detector, Appl. Phys. Lett.,vol. 79, no. 6, pp. 705707, Aug. 2001.

iii. E. Ejrnaes, A cascade switching superconductingsingle photon detector, Appl. Phys. Lett., vol. 91,p. 262509, Dec. 2007.

iv. A. Verevkin, J. Zhang, and R. Sobolewski,

Detection efficiency of large-active-area NbNsingle-photon superconducting detectors in theultraviolet to near-infrared range, Appl. Phys.Lett., vol. 80, no. 25, pp. 46874689, June 2002.

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