TransistorTransistor

Victor Hugo Estrada RiveraVictor Hugo Estrada RiveraUniversity of Texas at El PasoUniversity of Texas at El Paso

Molecular Electronics Molecular Electronics

Chem 5369Chem 5369

DefinitionDefinition An electronic device made of a semiconductor that can An electronic device made of a semiconductor that can

act as an insulator and a conductor. act as an insulator and a conductor. The ability to change from these two states enables the The ability to change from these two states enables the

device switch or amplify.device switch or amplify. It has of three components:It has of three components:

SourceSource GateGate DrainDrain

http://www.privateline.com/TelephoneHistory3/History3.html

ImportanceImportance

“The Transistor was probably the most important invention of the 20th Century and the story behind the invention is one  of clashing egos

and top secret research.”

Ira Flatow

Transistors replaced vacuum tubes.Transistors replaced vacuum tubes.

Transistors are central to the Integrated Circuit, and Transistors are central to the Integrated Circuit, and therefore, all electronic devices of the information therefore, all electronic devices of the information age, such as: pc’s, cellular phones, ipods, pda’s, age, such as: pc’s, cellular phones, ipods, pda’s, intelligent cars and buildings…….. are made possible.intelligent cars and buildings…….. are made possible.

TimelineTimeline18

74

1895

1906

1945 19

47 1948 19

50 1957 19

58 1968

1883

1898

1907

1955

1934

1928 19

36

How a transistor works?

•Click on a Year to Learn its Significance•Click on the Blue Triangle to Return•You can also click to see how a transistor works

18741874 Ferdinand Braun discovered Ferdinand Braun discovered

RectificationRectification crystals that can conduct crystals that can conduct

current in only one direction current in only one direction under certain conditions.under certain conditions.

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http://en.wikipedia.org/wiki/Image:Ferdinand_Braun.jpg

18831883

Edison effect ( thermionic Edison effect ( thermionic emission). emission). The flow of electrons from The flow of electrons from

metals caused by thermal metals caused by thermal vibration energy (heat) that vibration energy (heat) that overcomes the electrostatic overcomes the electrostatic forces that hold the electrons forces that hold the electrons to the surface.to the surface.

http://en.wikipedia.org/wiki/Image:Thomas_Edison.jpg ◄◄

18951895

Guglielmo Marconi -Guglielmo Marconi -sent a radio signal sent a radio signal over a distance of over a distance of more than a mile.more than a mile.

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http://en.wikipedia.org/wiki/Image:Marconi.jpg

18951895

John Ambrose Fleming -John Ambrose Fleming -developed the Vacuum developed the Vacuum TubeTube a device that a device that modifymodify a a

signal by controlling the signal by controlling the movement of electrons in movement of electrons in an evacuated space.an evacuated space.

The electrons flow only The electrons flow only from filament to plate from filament to plate creating a diode (a device creating a diode (a device that can conduct current that can conduct current only in one direction)only in one direction)

http://en.wikipedia.org/wiki/Image:Diode_vacuum_tube.png ◄◄

http://concise.britannica.com/ebc/art-58608

18981898

Thomson discovered Thomson discovered the electron.the electron.

http://en.wikipedia.org/wiki/Image:Jj-thomson2.jpg

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19061906

Lee De Forest -Triode in Lee De Forest -Triode in vacuum tube (vacuum tube (amplifyamplify signals) allowing farther signals) allowing farther telephone conversations.telephone conversations.

The problems with this The problems with this Triode is that it was Triode is that it was unreliable and used a lot unreliable and used a lot of power.of power.

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http://en.wikipedia.org/wiki/Image:Deforest.jpg

http://en.wikipedia.org/wiki/Image:Triode_vacuum_tube.png

19071907

Bell telephone patents Bell telephone patents expire.expire.

AT&T (Bell’s company) AT&T (Bell’s company) bought De Forest’s bought De Forest’s triode patent.triode patent.

Result: transcontinental Result: transcontinental telephone service.telephone service.

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http://en.wikipedia.org/wiki/Image:Alexander_Graham_Bell22.jpg

19281928

The first patents for the The first patents for the

transistor principle weretransistor principle were

registered in Germany by registered in Germany by

Julius Edgar Lilienfield.Julius Edgar Lilienfield.He proposed the basic He proposed the basic

principle behind the MOS principle behind the MOS

field-effect transistorfield-effect transistorhttp://chem.ch.huji.ac.il/~eugeniik/history/lilienfeld.htm

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19341934

German Physicist Dr. German Physicist Dr. Oskar Heil patented Oskar Heil patented the field effect the field effect transistortransistor

http://www.precide.ch/eng/eheil/eheil.htm

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19361936

Mervin Kelly Bell Lab's Mervin Kelly Bell Lab's director of research. He director of research. He felt that to provide the felt that to provide the best phone service it will best phone service it will need a better amplifier; need a better amplifier; the answer might lie in the answer might lie in semiconductors. And he semiconductors. And he formed a department formed a department dedicated to solid state dedicated to solid state sciencescience

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http://www.pbs.org/transistor/album1/addlbios/kelly.html

19451945 Bill Shockley the team leader of Bill Shockley the team leader of

the solid state department the solid state department (Hell’s Bell Lab) hired Walter (Hell’s Bell Lab) hired Walter Brattain and John Bardeen.Brattain and John Bardeen.

He designed the first He designed the first semiconductor amplifier, relying semiconductor amplifier, relying on the field effect. on the field effect.

His device was a small cylinder His device was a small cylinder coated thinly with silicon, coated thinly with silicon, mounted close to a small, metal mounted close to a small, metal plate. plate.

The device didn't work, and The device didn't work, and Shockley assigned Bardeen and Shockley assigned Bardeen and Brattain to find out why. Brattain to find out why.

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http://www.lucent.com/minds/transistor/history.html

19471947 Bardeen and Brattain built the point contact Bardeen and Brattain built the point contact

transistor.transistor. They made it from strips of gold foil on a plastic They made it from strips of gold foil on a plastic

triangle, pushed down into contact with slab of triangle, pushed down into contact with slab of germanium.germanium.

◄◄http://www.lucent.com/minds/transistor/history.html

http://www.lucent.com/minds/transistor/history.html

http://www.lucent.com/minds/transistor/history.html

1947 cont.1947 cont.

1947 cont.1947 cont.

Shockley make the Shockley make the Junction transistor Junction transistor (sandwich).(sandwich).

This transistor was more This transistor was more practical and easier to practical and easier to fabricate.fabricate.

The Junction Transistor The Junction Transistor became the central became the central device of the electronic device of the electronic age age

http://www.ecse.rpi.edu/Homepages/schubert/Unused%20stuff/Educational%20resources/Picture%20First%20junction%20transistor.jpg

1947 cont.1947 cont.

A thin piece of semiconductor of one type between two slices of another type, is able to control the flow of the current between emitter and the collector.

Even if the input current is weak, the transistor can control a strong current.

The effect accomplish is that the current through the collector mimics and amplify the behavior of the current through the Emitter.

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19481948

Bells Lab unveil the transistor.Bells Lab unveil the transistor.They decided to name it transistor instead They decided to name it transistor instead

of Point-contact solid state amplifier. of Point-contact solid state amplifier. John Pierce invented the name, combining John Pierce invented the name, combining

transresistance with the ending common transresistance with the ending common to devices, like varistor and thermistor.to devices, like varistor and thermistor.

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1950’s1950’s

Sony receives a license from Sony receives a license from Bell Labs to build transistorsBell Labs to build transistors

In 1946 Sony produced In 1946 Sony produced products for radio repair. In products for radio repair. In 1950 they decided to build 1950 they decided to build something for the mass something for the mass consumption; the transistor consumption; the transistor radio. radio.

In United States they used In United States they used the transistors primarily for the transistors primarily for computers and military uses.computers and military uses.

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http://www.sony.net/Fun/SH/1-6/h2.html

19551955

Foundation of Shockley Semiconductor, Foundation of Shockley Semiconductor, sowing the seeds of silicon valleysowing the seeds of silicon valley

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http://en.wikipedia.org/wiki/Image:SJPan.jpg

http://en.wikipedia.org/wiki/Image:ShockleyBldg.jpg

19571957

The traitorous eight abandoned Shockley The traitorous eight abandoned Shockley founding Fairchild Semiconductor.founding Fairchild Semiconductor.

◄◄http://www.fairchildsemi.com/company/history_1957.html

19581958 Jack Kilby of Texas Instruments – Jack Kilby of Texas Instruments –

Invent the Integrated CircuitInvent the Integrated Circuit (IC) (IC) It occurred to him that all parts of It occurred to him that all parts of

a circuit could be made out of the a circuit could be made out of the same piece of silicon. same piece of silicon.

The entire circuit could be built The entire circuit could be built out of a single crystal out of a single crystal

Reducing the size Reducing the size Easier to produce Easier to produce

◄◄Texas Instruments' first IC

1958 cont. - Integrated Circuit1958 cont. - Integrated Circuit

A single device that A single device that contains an contains an interconnected array interconnected array of elements like of elements like transistors, resistors, transistors, resistors, capacitors, and capacitors, and electrical circuits electrical circuits contained in a silicon contained in a silicon wafer.wafer.

http://www.helicon.co.uk/online/datasets/samples/education/images.htm

http://www.ece.uiuc.edu/grad/7reasons/5reputation.html

19681968Bob Noyce and Gordon Moore, two of the Bob Noyce and Gordon Moore, two of the

traitorous eight together with Andy Grove, traitorous eight together with Andy Grove, form Intel Corporationform Intel Corporation

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http://www.granneman.com/techinfo/background/history/

http://www.itnews.sk/buxus_dev/images/2006/Intel_logo_nove1_velky.jpg

How a Transistor WorksHow a Transistor Works

The transistor can function as: An insulator

A conductor

The transistor's ability to fluctuate between these two states that

enables to switch or amplify.

The transistor has many applications, but only two basic functions:

switching and modulation (amplification).

In the simplest sense, the transistor works like a dimmer. With a push the knob of the dimmer, the light comes on and off. You

have a switch. Rotate the knob back and forth, and the light grows

brighter, dimmer, brighter, dimmer. Than you have a modulator.

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How a Transistor Works cont.How a Transistor Works cont. Both the dimmer and the

transistor can control current flow.

Both can act as a switch and as a modulator/amplifier.

The important difference is that the “hand” operating the transistor is millions of times faster.

http://www.ieicorp.com/consum/dimmer.gif

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Transistors are made of semi-conductors such as silicon and gallium arsenide.

These materials carry electricity not well enough to be called conductors; not badly enough to be called insulators.

Hence their name semiconductor. The importance of a transistor is in its ability to

control its own semi conductance, namely acting like a conductor when needed, or as an insulator (nonconductor) when that is needed.

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You can compare a transistor to an ordinary faucet. You can compare a transistor to an ordinary faucet. The water enters the faucet in the pipeline from the The water enters the faucet in the pipeline from the

water distributor, which would correspond to the source water distributor, which would correspond to the source in the Transistor.in the Transistor.

The water then leaves the faucet into the sink, this would The water then leaves the faucet into the sink, this would be the drain in the Transistor. be the drain in the Transistor.

The water tap controls the amount, flow, of water. In the The water tap controls the amount, flow, of water. In the Transistor the gate operates as this controller. Transistor the gate operates as this controller.

With a small force you can control the water flow with the With a small force you can control the water flow with the water tap, just as you can control the current flowing water tap, just as you can control the current flowing from the source to the drain, with a small change of the from the source to the drain, with a small change of the charge of the gate. charge of the gate.

http://nobelprize.org/educational_games/physics/transistor/function/watertap.html ◄◄

Transistors are Made of SiliconTransistors are Made of Silicon

Silicon is a grey colored element with crystalline Silicon is a grey colored element with crystalline structure. structure.

It is the second most abundant element in the earth's It is the second most abundant element in the earth's crust, after oxygen. crust, after oxygen.

Silicon is always found in combined form in nature, often Silicon is always found in combined form in nature, often with oxygen as quartz, and is found in rocks and silica with oxygen as quartz, and is found in rocks and silica sand. sand.

To be able to use silicon as a semiconductor, it needs to To be able to use silicon as a semiconductor, it needs to be in a very pure form. be in a very pure form.

If there is more than one impure particle in a million, the If there is more than one impure particle in a million, the silicon can not be used. silicon can not be used.

Silicon is the most frequently used semiconducting Silicon is the most frequently used semiconducting material today. material today.

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DopingDoping

The addition of a small The addition of a small amount of a different amount of a different substance to a pure substance to a pure semiconductor crystal. semiconductor crystal.

The impurities give an The impurities give an excess of conducting excess of conducting electrons or an excess of electrons or an excess of conducting holes which is conducting holes which is crucial for making a crucial for making a working transistor.working transistor.

http://www.astro.virginia.edu/class/oconnell/astr511/im/Si-B-doping-JFA.jpg

n-type doping

p-type doping ◄◄

Acceptor doping

Donor doping

http://131.104.156.23/Lectures/CHEM_462/462_chapter_1.html

http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/dsem.html#c2 ◄◄

Energy gap

Conduction Band

Valence BandMetals

Conduction Band

Valence Band

SemiconductorsSemiconductors

Conduction Band

Valence Band

InsulatorsBigger Energy gap

Conduction Band: Is a part in which electrons can move freely and can accelerate under an electric field, constituting an electric current.

Valence Band: Is a part of the molecule, called band, where you can find the electrons

Energy Gap: Is the energy difference between the valence gap and the conduction band

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Transistor typesTransistor types

MOS - Metal Oxide Semiconductor MOS - Metal Oxide Semiconductor FET - Field Effect Transistor FET - Field Effect Transistor BJT - Bipolar Junction TransistorBJT - Bipolar Junction Transistor

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Moore’s LawMoore’s Law

It’s an observation made by Gordon E. It’s an observation made by Gordon E. Moore, in which he predicted that the Moore, in which he predicted that the number of transistors, inside an Integrated number of transistors, inside an Integrated Circuit, could be doubled every 24 months.Circuit, could be doubled every 24 months.

At the density that also minimized the cost At the density that also minimized the cost of a transistor. of a transistor.

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http://upload.wikimedia.org/wikipedia/commons/0/06/Moore_Law_diagram_%282004%29.png ◄◄

Transistor problemsTransistor problems

Power density increased

Device variability

Reliability

Complexity

Leakage

Power dissipation limits device density

Transistor will operate near ultimate limits of size and

quality – eventually, no transistor can be fundamentally

better

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The Future of transistorsThe Future of transistors Molecular electronics Carbon nanotubes transistors Nanowire transistors Quantum computing CMOS devices will add

functionality to CMOS non-volatile memory, opto-electronics, sensing….

CMOS technology will address new markets macroelectronics, bio-medical devices, …

Biology may provide inspiration for new technologies bottom-up assembly, human intelligence

"Photo: National Research Council of Canada.“http://www.nrc-cnrc.gc.ca/multimedia/picture/fundamental/nrc-nint_moleculartransistor_e.html ◄◄

http://www.bellsystemmemorial.com/belllabs_transistor.html

Pictorial History of TransistorsPictorial History of Transistors

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Further ResourcesFurther Resources Riordan, Michael and Lillian Hoddeson. Crystal Fire: The Invention of the Riordan, Michael and Lillian Hoddeson. Crystal Fire: The Invention of the

Transistor and the Birth of the Information Age. New York: W. W. Norton Transistor and the Birth of the Information Age. New York: W. W. Norton and Company, 1997.and Company, 1997.

Brattain, Walter H. "Genesis of the Transistor." The Physics Teacher. Brattain, Walter H. "Genesis of the Transistor." The Physics Teacher. (March, 1968) pp. 109-114.(March, 1968) pp. 109-114.

Hoddeson, Lillian. "The Roots of Solid State Research at Bell Labs." Hoddeson, Lillian. "The Roots of Solid State Research at Bell Labs." Physics Today. (March, 1997).Physics Today. (March, 1997).

Holonyak, Jr., Nick."John Bardeen and the Point-Contact Transistor." Holonyak, Jr., Nick."John Bardeen and the Point-Contact Transistor." Physics Today. Physics Today.

(April, 1992).(April, 1992). Shockley, William. "How We Invented the Shockley, William. "How We Invented the Transistor." New Scientist 21.

(December, 1972) pp. 689-91. http://www.pbs.org/transistor http://www.aip.org/history http://www.lucent.com/minds/transistor/history.html http://chem.ch.huji.ac.il/~eugeniik/history/lilienfeld.htm http://en.wikipedia.org/wiki/Main_Page You can find two very cool games on transistors in the next link: http://nobelprize.org/educational_games/physics/transistor/function/intro.html

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