Transcript ATM or STM Used to Determine Chirality

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 Graphene
Ch = n a1 + m a2 (n, m); (n, m are integers; 0  m  n).
L  Ch  Ch  Ch  a n 2  m 2  nm
cos = Ch  a1 / |Ch||a1|.
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DL

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Nanotube Chirality
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Examples 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 Tube
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ATM or STM Used to Determine Chirality
(11,7)
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Multi Wall Tubes
Multi-wall CNT
TEM Image
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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
CNT cable
Super strong, light
weight
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Space Elevator
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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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Structure
Fabricated on a silicon wafer, CNT ribbons are suspended
100 nanometers above a carbon substrate layer.
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Off-State
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On-State
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Read-Out
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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
C
A
B
A: Laser ablation;
B: Arc discharge;
C: Catalytic chemical vapor deposition
(CCVD).
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All currently known methods consist of
some variant of one of these
approaches.
Bottom-up Growth of CNTs
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CNT Nanoelectrode Array
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Si Nanowires
A Si nanowire MOSFET
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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 bottomup electronics will mean to semiconductor technology of the future.
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