s. e. thompson eel 6935 today’s subject continue on some basics on single-wall cnt---- chiral...

S. E. Thompson EEL 6935

Today’s Subject

Continue on some basics on single-wall CNT----chiral length, angle and band gap;

Other properties of CNT; Device applications; Growth of CNT; Si nanowires; Other nanowires; Growth Challenges.

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““Roll” Carbon Nanotube from GrapheneRoll” Carbon Nanotube from Graphene

nmmnaCCCL hhh 22

LD

Ch = n a1 + m a2 (n, m); (n, m are integers; 0 m n).

cos = Ch a1 / |Ch||a1|.

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Nanotube ChiralityNanotube Chirality

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Examples of Band StructuresExamples of Band Structures

One-dimensional energy dispersion relations for (a) armchair (5, 5), (b) zigzag (9, 0), and (c) zigzag (10, 0) carbon nanotubes.

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Bandgap of Semiconducting TubeBandgap of Semiconducting Tube

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ATM or STM Used to Determine Chirality

(11,7)

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Multi-wall CNT

TEM Image

Multi Wall Tubes

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Material Properties of CNT-continued

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Comparison of Other Materials to CNT

Material Young’s Modulus (GPa) (Modulus of Elasticity)

Yield Strength(Gpa)

Concrete, High Strength

30 0.04 ?

Aluminum 69 0.095

Titanium Alloy 105-120 0.73

Si 170 ?

Steel 200 0.69

Diamond 1050-1200 ?

SWCNT/MWCNT 1050/1200 (same as diamond)

~200

Space Elevator

CNT cableSuper strong, light weight

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Material Properties of CNT-continued

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Electronic Applications

CNT transistor

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Demonstration of CNT Memory Design

http://www.nantero.com/index.html

Applied charge make CNT ribbons bend down to touch the substrate or bend up back to its original state.Ribbon-up gives 'zero' and ribbon-down is 'one'.

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Structure13

Fabricated on a silicon wafer, CNT ribbons are suspended 100 nanometers above a carbon substrate layer.

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Off-State14

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On-State15

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Read-Out16

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Structural and Mechanical Applications

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CNT interconnect Lines

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Bottom-up Approach for CNT interconnects

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Sensors, NEMS Applications

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CNT-based Bio Sensors

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Carbon Nanotube Growth

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Three Basic CNT Growth Methods

A: Laser ablation;B: Arc discharge;C: Catalytic chemical vapor deposition (CCVD).

All currently known methods consist of some variant of one of these approaches.

A

B

C

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Bottom-up Growth of CNTs

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CNT Nanoelectrode Array

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Si Nanowires

A Si nanowire MOSFET

Ultrahigh piezoresistance of Si nanowire: sensor application, actuator, microscope cantilever, etc.

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Si Nanowire Growth

Vapor-Liquid-Solid mechanism Si nanowire growth.Difference between Si nanowire and CNT: CNT is hollow, but Si nanowire is solid with crystalline core.

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Si Nano Wire Transistors

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Nanowire-based Vertical Gate Transistor

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ZnO Nanowires

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Challenges of Nanowire Growth

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Challenges of Nanowire Growth

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Nanoelectronics – Now or Never?" IEDM Evening Panel Discussion, December 14,

Session 26: 8:00 p.m. Continental Ballroom 6-9 Moderator: Mark Lundstrom, Purdue University "Nanoelectronics – Now or Never?" Traditional 'top-down' microelectronics has become nanoelectronics with device dimensions comparable to those being explored in the new field of ëbottom-up' nano- and molecular electronics. We use the terms, top-down and bottom-up, in a very general sense. Top-down refers to a way of thinking and building that begins at the macro (continuum) scale and pushes to the nanoscale. Bottom-up refers to a way of thinking and building that begins at the atomistic level and builds up to the nanoscale. The top-down approach has already delivered silicon MOSFETs with channel lengths of ~ 5nm, but scaling down device dimensions with commensurate increase in device and system performance is increasingly challenging. Bottom-up technology has demonstrated molecular switches, nanotube and nanowire FET's, NDR and single electron devices, and ultra-dense memory prototypes. Is bottom-up nanotechnology ready to address the industry's challenges, or is it still long-term research with essentially unpredictable outcomes? This panel will debate the question of what the intersection of top-down and bottom-up electronics will mean to semiconductor technology of the future.