Transcript Presentations\Carbon Nanotubes and Related_ Devices and

Carbon nanotube is a magic material. The unique structure brings it
amazing characteristics. Lots of people believe that the usage of carbon
nanotube will bring technology revolution to the industry. In this
presentation, we will focus on two stunning properties that related to
our major. And use some real stories to help you understand how the
carbon nanotubes will change the future of the semiconductor industry.
Presented by:
Peng Zhiyuan, Chen Jiadong
April 30, 2014
Outline
 Who invented the carbon nanotube?
 What is a carbon nanotube?
--unique structures and properties
 What are the applications
--CNTFET and Heat dissipation
Major Contributors: Sumio Iijima
A leading researcher at NEC Laboratories since
the late 1980’s.
 Discovered carbon nanotubes in 1991 by
demonstrating that the carbon fibers produced
by a carbon arc were hollow.
Carbon nanotube structure
 Roll a graphene sheet in a certain direction:
• Armchair structure
conductor
• Zigzag structure
semiconductor
• Chiral structure
semiconductor
Armchair
Zigzag
Chiral
Chiral vector:
Depending on their n,m values,
nanotubes can be either
electrically metallic or semiconductor.
In general, an (n, m) SWNT will be
metallic when
n - m = 3q, where q = 0, 1, 2, 3, 4, 5……
CNTFET
Back Gate
Top Gate
The tube conducts at negative Vg and turns off with a positive Vg.
The resistance change
between the on and off state is many orders of magnitude. This
device behavior is analogous to a p-type metal–oxide–
semiconductor field-effect transistor (MOSFET)
Why we need CNTFET?
22nm
Physical limits force us to take action
 For the Microelectronic device the performance is
controlled by the semiconductor material doping
concentration. In nanometer scale ,corresponding
statistical error could be as high as 10 percent or higher.
•Nanotube transistors can operate even without dopants and
are less sensitive to differences in the channel length.
•A typical carbon nanotube’s diameter is between 1 ~ 2 nm.
Advantages
 Carbon nanotube structure is an ideal onedimensional conductive path.
 Better control over channel formation
 High electron mobility
 High current density
 Small switch time
Invert
Giga to Tera
Heat dissipation
One of the greatest challenges in
semiconductor design is
finding ways to move waste heat out of a
structure and into whatever dissipation area
is designed for it.
One of the most significant problems facing modern CPUs
is the efficient transmission of heat between the CPU cores
and the heat sinks.
Traditional way
Moving heat more efficiently into the
heatsink would reduce CPU core temps
and allow for higher frequency operation.
Why?
Thermal Interface Material
Same price, better performance
Thermal properties of CNT
Nanotubes are expected to be very good thermal
conductors along the tube, exhibiting a property
known as "ballistic conduction", but good
insulators laterally to the tube axis.
Measurements show that a SWNT has a roomtemperature thermal conductivity along its axis of
about 3500 W·m−1·K−1. compare this to copper, a
metal well known for its good thermal
conductivity, which transmits 385 W·m−1·K−1.
A SWNT has a room-temperature thermal
conductivity across its axis (in the radial direction)
of about 1.52 W·m−1·K−1, which is about as
thermally conductive as soil.
The Lawrence Berkeley National Lab (Berkeley
Lab) team is working on a method that would
ensure more of the nanotubes come into
contact with the actual metal layer .
The six-fold improvement
--Using organic compounds
--strong covalent bonds between the carbon
nanotubes and the metal layer at the top of a
chip.
--thermal interface material can conduct heat
6x more effectively off the top of a chip
Same price, much better performance
Conclusion
 Carbon nanotube shows its great potential to change
the electronics industry. But, currently there is no
effective technology for mass production and
production cost is still very high.
 However, those amazing characteristics of carbon
nanotude continuously arose researchers’ interest.
 We believe those difficulties will be overcome soon.
Key concepts
 The structure of a nanotube strongly affects its




electrical properties.
Carbon nanotube structure is an ideal onedimensional conductive path.
Faster switching time.
Ballistic termal conduction
Increase the operation frequency of processors.
Questions?
References

1. University at Buffalo. "Carbon Nanotubes Are Superior To Metals For Electronics, According to
Engineers." ScienceDaily. ScienceDaily, 24 March 2009.
<www.sciencedaily.com/releases/2009/03/090320134041.htm>.

2. Ghosh, S. et al. (2008). "Extremely high thermal conductivity of graphene: Prospects for thermal
management applications in nanoelectronic circuits". Applied Physics Letters 92 (15): 151911.

3. Prabhakar R. Bandaru. (2007). "Electrical Properties and Applications of Carbon Nanotube Structures“
Journal of Nanoscience and Nanotechnology. American Scientific Publishers.

4. Phaedon Avouris. Joerg Appenzeller. Richard Martel. Shalom J. Wind. (2003)" Carbon Nanotube
Electronics " . IEEE, VOL. 91, NO. 11

5. Ga-Lanee Chen, Jyh-Chain lin, Tai-Cherng Yu, Charles Leu. (2006)“Heat sink with carbon nanotubes and
method for manufacturing” Patent No. 7086 451 B2.
Thank You!