Nanoscale Science and Engineering NSF, Arlington, VA Science and Engineering NSF, Arlington, VA Dec. 6, 2010 ... giant magneto-resistance spintronics + ... Device Operating Principle:

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  • Nanoscale Science and EngineeringNSF, Arlington, VA

    Dec. 6, 2010Eli Yablonovitch, Berkeley EECS Dept.

  • Electronics / network electricity use

    Buildings Electricity: ~2,700 TWh

    CommercialResidential

    Electronics

    Networked~150 TWh ?

    Net. Eqt.~ 20 TWh

    U.S. only Annual figurescirca 2006

    All approximate

    One central baseload power plant (about 7 TWh/year)

    ~290 TWh

    Bruce Nordman, LBL

    Tel.

  • Because power consumption Vdd2and Vdd (operation voltage) scaling has slowed after 0.13m node.

    High Performance ITRS Roadmap

    0.7 V0.8 V0.9 V1.0 V1.1 V1.2 V1.3 V1.8 V2.5 VVdd

    16 nm

    22 nm

    32 nm

    45 nm

    65 nm

    90 nm

    0.13 m

    0.18 m

    0.25 m

    Technology Node

    Power Usage Rising Faster Than Past Trend

  • Units:

    ~40kT/bit of information

    0.16 atto-Joules/bit of information

    0.16 nano-Watts/Gbit/second

    This is about 106 times less energy than we are using today!

  • What will be the energy cost, per bit processed?

    1. Logic energy cost ~40kT per bit processed

    2. Storage energy cost ~40kT per bit processed

    3. Communications currently >100,000kT per bit processed

    .

  • There are many type of memory possible:1. Flash2. SRAM3. Dram4. Magnetic Spin5. Nano-Electro-Chemical Cells6. Nano-Electro-Mechanical NEMS7. Memristor8. Chalcogenide glass (phase change)9. Carbon Nanotubes

    Similarly there are many ways to do logic.

    But there are not many ways to communicate:

    1. Microwaves (electrical)2. Optical

  • Moore

    You?

  • !

    Transistor

  • fkTR

    V

    fRkTV

    noise

    noise

    =

    =

    4

    42

    2

    What is the energy cost for electrical communication?

    Signal Noise PowerEnergy per bit = 4kT per bit

    All information processing costs ~ 40kT per bit. (for good Signal-to-Noise Ratio)

    Great!

    So whats the problem?

  • {

    mVolt1V

    CqqkT4VCq

    qkT4V

    C1kT4V

    RC1RkT4V

    fRkT4V

    Volts10mVolts100noise

    2noise

    2noise

    2noise

    2noise

    =

    =

    =

    =

    =

    //321

    The natural voltage range for wired communication is rather low:

    The thermally activated device wants at least one electron at ~1Volt.

    The wire wants1000 electrons at 1mVolt each.

    (to fulfill the signal-to-noise requirement >1eV of energy)

    Voltage Matching Crisis at the nano-scale!

    If you ignore it the penalty will be (1Volt/1mVolt)2 = 106

    The natural voltage range for a thermally activated switch like transistors is >>kT/q, eg. ~ 40kT/q

    or about ~1Volt

  • "In addition, power is needed primarily todrive the various lines and capacitances associated with thesystem. As long as a function is confined to a small area ona wafer, the amount of capacitance which must be driven isdistinctly limited. In fact, shrinking dimensions on an integratedstructure makes it possible to operate the structure athigher speed for the same power per unit area."

    p. 114

  • 10m

    1m

    100nm

    10nm

    Moore's Law

    1960 1980 2000

    Crit

    ical

    D

    imen

    sion

    2020 2040 2060Year

    Tech

    nolo

    gy G

    ap

    Gates only

    Gates including wires

    107

    105

    102

    1

    0.1

    104

    106

    10

    108

    103

    Ene

    rgy

    per B

    it fu

    nctio

    n (k

    T)

    The other , for energy per bit function

    Shoorideh and Yablonovitch, UCLA 2006

    Transistor Measurements by Robert Chau, Intel

  • nano-transformerh

    ~1eV

    A low-voltage technology, or an impedance matching device,needs to be invented/discovered at the Nano-scale:

    transistor amplifier with steeper sub-threshold slope

    photo-diode

    + ++

    -

    +VG

    MEM's switch

    Cryo-ElectronicskT/q~q/C

    Cu

    Cu

    solid electrolyte

    Electro-Chemical Switch

    giant magneto-resistancespintronics

    +

    TFET'sNegative Capacitance Gates

    --V2O5 metal-insulator transition

  • Theme1 Nanoelectronics:SolidStateMilliVoltSwitching

  • An amplifying transistor as a voltage matching device:Small voltage inLarge voltage out

    in

    outAmplification of weak signals has an energy cost!Amplification of weak signals has a speed penalty!

    Gate Voltage

    Cur

    rent

    Vg

    ln{I}

    steeper sub-threshold

    slope

  • The Zener Diode:

    EFc

    EFv

    band

    to b

    and

    tunn

    elin

    g

    Bias Voltage

    Diff

    usio

    n cu

    rren

    t

    Cur

    rent

  • EF

    band

    to b

    and

    tunn

    elin

    g

    Bias Voltage

    Diff

    usio

    n cu

    rren

    t

    Sharp Step

    Cur

    rent

    The Esaki Diode:

  • The Backward Diode as a Switch:

    EFc

    EFv

    band

    to b

    and

    tunn

    elin

    g

    Bias Voltage

    Diff

    usio

    n cu

    rren

    t

    Cur

    rent

    Sharp Step

    The Backward Diode:These have been routinely made in Ge homo-junctions,since the 1960's.

  • Modulate the Tunneling Barrier

    Density of States Switch

    2 Ways to Obtain Steepness

    Thesubthresholdslopefortunnelingdependsonthesteepnessof

    thebandedges:

  • AllTheCasesN

    IP

    Z

    I

    ZP

    N

    YI P

    N

    Z

    NI

    P

    Z

    IP

    N

    ZLZ,i

    ZIP

    X

    N

    NP

    Z

    IP

    N

    Z

    N

    IP

    Z

    X

    24

  • I

    ZP

    N

    IP

    N

    ZLZ,i

    IP

    N

    Z

    )(***2 32

    *232 ETEV

    meJ ZiOLDDr

    h=

    )(** ,,32,22 ETEEemJ fZiZAreaDD

    r

    h=

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    2

    32

    *333 =

    r

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    ConstantI

    I

    VG

  • NI

    P

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    P

    Z

    NP

    Z

    )(**2*210 ETEheI ZiDD

    r=

    )(*)(***4*2 ,,00 fifZiZDD EEETEEheI =

    r

    )(**22

    Point,11 =r

    TVheJ OLDD

    I

    VG

    ConstantI

    I

    VG

    I

    VG

  • YI P

    N

    Z

    ZIP

    X

    N

    N

    IP

    Z

    X

    )(***2 222/3

    21 ETVEmeJ OLZiDD

    r

    h=

    )(1**2 ,,222/1

    ,11 ETVEEmeJ

    OLfZiZEdgeDD

    r

    h=

    )(*3

    2 2/322

    2/5Edge,22 ETV

    meJ OLDDr

    h=

    I

    VG

    2/3OLVI

    I

    VG

    OLVI

    VG

    OLVI 1

  • EC

    OFF

    material2(AlGaSb)

    oxide

    gatemetal

    quantumwell1(I

    nAs)

    EF

    EV

    EF

    EC

    ON

    EF

    EF

    EV

    oxide

    gatemetal

    quantumwell1(I

    nAs)

    material2(AlGaSb)

    EC

    SHARPLYOFF

    material2(AlGaSb)

    oxide

    gatemetal

    quantumwell1(InA

    s)

    EF

    EV

    EF

    CDEP

    CQW

    COX

    z

  • Theme 1:Key Scientific Questions (Kickoff Meeting 2010)

    New examples of Type III Energy band offsets need to be discovered.

    Fundamental band edge abruptness is very poorly understood.

    We need to concentrate on 2d/2d pn junctions

    Do we want to go all the way to monolayer/monolayer pn junctions?

    Will that guarantee reproducible thresholds?

  • nano-transformerh

    ~1eV

    A low-voltage technology, or an impedance matching device,needs to be invented/discovered at the Nano-scale:

    transistor amplifier with steeper sub-threshold slope

    photo-diode

    + ++

    -

    +VG

    MEM's switch

    Cryo-ElectronicskT/q~q/C

    Cu

    Cu

    solid electrolyte

    Electro-Chemical Switch

    giant magneto-resistancespintronics

    +

    TFET'sNegative Capacitance Gates

    --V2O5 metal-insulator transition

  • Theme2 NanoMechanics:SolidStateMilliVoltSwitching

  • WhyMechanicalSwitches?

    Relayshavezerooffstateleakagezerostaticenergy

    Source

    DrainGate

    Air gap

    tgap tdimple

    32

    3-Terminal Relay

    Relaysswitchon/offabruptlyallowsforaggressiveVDD scaling(ultralowdynamicenergy)

    Measured I-V

    Gate Voltage

    Dra

    in C

    urre

    nt

    S0.1mV/dec

    VPIVPO

  • RelayOnStateResistance

    ~1KOhmresistanceisacceptableforperformance.Formationofmetalmetalbondsintheonstateisnotnecessary!

    Physicalcontactcanbeavoidedaltogether,toeliminatesurfaceadhesion,withadeformabledielectric:

    33

    tunnelingcurrent

    Electrodescanbecoatedtoimprovereliability:

    dielectric

  • TunnelingNanoswitch

    Advantages: easeoffabricationandpackaging

    betterdevicereliability

    DeviceOperatingPrinciple: Electrostaticactuationofelectrode Conductionviatunneling

    nanoconductors embeddedinadeformablematrix

    7.7

    mV

    / D

    ecad

    e

    Pull-In/Pull-Out

    Bulovic / Lang (MIT)

  • Tunneling Micro-Electro-Mechanical Systems:

    Double Win:

    1. By never making direct contact, we don't pay the energy price of theinterfacial energy.

    2. By never making direct contact, the reliability issues are greatly eased.

    This comes at the price of higher resistance, but we know the wires in chips have a

    characteristic impedance ~1000 Ohms.

    This is achievable by tunneling without direct contact!

  • nano-transformerh

    ~1eV

    A low-voltage technology, or an impedance matching device,needs to be invented/discovered at the Nano-scale:

    transistor amplifier with steeper sub-threshold slope

    photo-diode

    + ++

    -

    +VG

    MEM's switch

    Cryo-ElectronicskT/q~q/C

    Cu

    Cu

    solid electrolyte

    Electro-Chemical Switch

    giant magneto-resistancespintronics

    +

    TFET'sNegative Capacitance Gates

    --V2O5 metal-insulator transition

  • Theme4 NanoPhotonics forUltraLowEnergyCommunication

  • Ultra-sensitive Floating Gate photodetector:

    Eliminate wire capacitance between photodetector and amplifierTransistor with a floating Ge-islandPhotonic crystal cavity with 1000efficiency improvement.

    SiO2

    Silicon

    Drain

    Source

    n-Si n-Si

    Ge islandn-Si channel

    Reflectors integrated with SOI waveguides to create a transverse cavity

    incident light

    Source Drain

    SiO2

    Silicon

    n-Sih+h+

    e- e-

    Photons modulate depletion widthGe

    -1000

    -800

    -600

    -400

    -200

    0

    200

    400

    600

    800

    1000

    Volta

    ge (

    V)

    0 100 200 300 400 500

    Time (ps)

    40psec

  • 39

    nano-transformerh

    ~1eV

    A low-voltage technology, or an impedance matching device,needs to be invented/discovered at the Nano-scale:

    transistor amplifier with steeper sub-threshold slope

    photo-diode

    + ++

    -

    +VG

    MEM's switch

    Cryo-ElectronicskT/q~q/C

    Cu

    Cu

    solid electrolyte

    Electro-Chemical Switch

    giant magneto-resistancespintronics

    +

    TFET'sNegative Capacitance Gates

    --V2O5 metal-insulator transition

  • Theme3 NanoMagnetics:SurmountingtheLandauer Limit

  • 41

    Fundamental Limits of Computing

    Charles BennettRolf Landauer

    Von Neumann-Landauer limit (1961):Energy lost in a logic operation in which 1 bit is lost is E kT ln 2

    John von Neumann

    Bennett (1973):Logical Reversibility of Computation

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