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Department of Materials Science and Engineering, Northwestern University
Nanomaterials
Lecture 6: Carbon Nanomaterials
Department of Materials Science and Engineering, Northwestern University
7 nm
STM Image
AFM Image
Carbon Nanomaterials
Department of Materials Science and Engineering, Northwestern University
• C60 was established by mass spectrographic analysis by Kroto and Smalley in 1985• C60 is called a buckminsterfullerene or buckyball due to resemblance to geodesic
domes designed and built by R. Buckminster Fuller
G. Timp, Nanotechnology, Chapter 7
Fullerenes
Department of Materials Science and Engineering, Northwestern University
• Endohedral doping of fullerenes leads to the formation of a dipole moment thatinfluences solubility and other properties.
G. Timp, Nanotechnology, Chapter 7
Endofullerenes
Department of Materials Science and Engineering, Northwestern University
G. Timp, Nanotechnology, Chapter 7
Electronic Structure of Molecular and Solid C60
Department of Materials Science and Engineering, Northwestern University
Calculated local density of states for Si(100)
Structure of C60
1.0
0.8
0.6
0.4
0.2
0.0
dI/d
V (A
.U.)
-2 -1 0 1 2Energy (eV)
C60 Si Dangling Bond H-passivated Si
Spectroscopic variation among surface features
70 Å x 70 Å
3-D STM Topograph
C60
DanglingBonds
Si
Ge
LUMO peak
Single Molecule STM Spectroscopy of C60
Department of Materials Science and Engineering, Northwestern University
G. Timp, Nanotechnology, Chapter 7
Rolled Up From Graphene Sheets:Carbon Nanotubes
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Carbon Nanotube Synthesis:Carbon Arc Discharge
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Carbon Nanotube Synthesis:Chemical Vapor Deposition
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Carbon Nanotube Synthesis:Laser Ablation
Department of Materials Science and Engineering, Northwestern University
G. Timp, Nanotechnology, Chapter 7
Chirality of Carbon Nanotubes
Department of Materials Science and Engineering, Northwestern University
G. Timp, Nanotechnology, Chapter 7
Energy Band Diagrams of Carbon Nanotubes
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Electrical Properties of Graphite
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Electrical Properties of Straight Nanotubes
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Electrical Properties of Twisted Nanotubes
Department of Materials Science and Engineering, Northwestern University
G. Timp, Nanotechnology, Chapter 7
Bandgap of Semiconducting Nanotubes
Department of Materials Science and Engineering, Northwestern University
• MWNT bandgap is proportional to 1/d At room temperature,MWNTs behave like metals since d ~ 10 nm
• Only the outermost shell carries current in an undamaged MWNT
Electrical Properties of MWNTs
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Other Properties of SWNTs
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Other Properties of SWNTs
Department of Materials Science and Engineering, Northwestern University
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Nanotubes as Interconnects
Department of Materials Science and Engineering, Northwestern University
Although a cross-sectional view of a MWNT shows severalcylindrical shells, only the outermost shell carries current inan undamaged MWNT.
Current Carrying Capacity of MWNTs
Department of Materials Science and Engineering, Northwestern University
8
6
4
2
0
Cur
rent
dens
ity(x
1013
A/m
2 )
1614121086420Electric field (x106 V/m)
Maximum current density: 6.8 x 1013 A/m2
Maximum electric field: 1.6 x 107 V/m
Maximum current densities of potential interconnect materials:• Metals: 1010 – 1012 A/m2
• Superconductors: Jc ~ 1012 A/m2
• MWNTs: >5×1013 A/m2
Representative MWNT I-V Curve:
Department of Materials Science and Engineering, Northwestern University
Experimental method: Monitor the current as a function of timewhile stressing the MWNT at a fixed voltage.
Before Electrical Stress
1 μm2 AFM image
After Failure
1 μm2 AFM image
Electrically Stressed MWNTs
Department of Materials Science and Engineering, Northwestern University
P. G. Collins, et al., Phys. Rev. Lett., 86, 3128 (2001).
Multiwalled Carbon Nanotube Failure
Department of Materials Science and Engineering, Northwestern University
G. Timp, Nanotechnology, Chapter 7
Device Applications of Nanotube Junctions
Department of Materials Science and Engineering, Northwestern University
P. G. Collins, et al., Science, 292, 706 (2001).
Engineering Carbon NanotubesUsing Electrical Breakdown
Department of Materials Science and Engineering, Northwestern University
P. G. Collins, et al., Science, 292, 706 (2001).
Engineering Carbon NanotubesUsing Electrical Breakdown
