Carbon Nanotubes and Related; Devices and Applications Andrew Turner 4/25/2015

Abstract Carbon nanotubes are small tubes of carbon fiber that are prized for their electrical, mechanical and thermal properties making them ideal for a variety of applications. CNTs small size and thermal properties make them ideal for future transistor and interconnect production providing a solution to the problem of Moore’s Law. In addition, CNT’s mechanical properties can be tied in with their electrical properties to produce a variety of sensors and related devices.

Key Terms CNT – Carbon nanotube SWNT – Single walled carbon nanotube MWNT – Multiwalled carbon nanotube

Outline and Introduction History Characteristics Production Applications

Questions What are carbon nanotubes? What determines if a nanotube has metallic or semiconductor properties? What must we do in order to use carbon nanotubes in gas sensors? What are some unique properties of carbon nanotubes? What is the major drawback for the use of carbon nanotubes in transistors?

History and Background First discovered by Sumio Iijma in 1991 while looking at soot from a Fullerene experiment. Sumio Iijma has received several honors and awards including the Kavli prize.

Characteristics Electrical conductivity is determined by how the tubes are rolled. The armchair configuration is used to create metallic tubes. The zigzag method can be used for either metallic or semiconducting tubes.

Characteristics Thermal conductivity along tube axis is twice that of diamond. High current densities exceeding A/cm 2.

Production Carbon nanotubes are created using single layers of graphite rolled up to form diameters of 1 to 100nm and up to millimeters in length. Arc discharge method using electrodes CVD – Chemical Vapor Deposition Laser induced traces of different types on catalyst metals

Production Chemical vapor deposition (CVD) is then used to grow the fibers in a catalyst containing gas with temperatures between 300 and 1150 degrees C. The fibers are collected from the deposition system and are placed in a solvent. The drying leaves the nanotubes in randomly distributed places.

Production The lower temperatures in the 300 to 1150 degree C range are used for multi-walled carbon nanotube production. The higher temperatures in the 300 to 1150 degree C range are used for single-walled carbon nanotube production. Single walled carbon nanotubes are desired for semiconductor use.

Applications Interconnects Transistors Sensors Energy storage

Use in Interconnects The use of carbon nanotubes in place of traditional polycrystalline interconnects allows for no ohmic scattering due to loss. Decreased signal delay Remember it is not always the interconnects for the delay. Devices themselves could cause the greatest delay. Since carbon nanotubes have an extremely high current density they are resistant to current crowding.

Use in Transistors Switching behavior first observed in 1998 where the conductivity was observed to be modulated by about five orders of magnitude CMOS device created when a section of a nanotube was doped using potassium thus reversing its conductivity. The CNTFET outperforms the prospective Si- MOSFET when using Guo’s theory.

Use in Transistors Guo’s theory showing predicted values for MOSFETs in 2016

Use in Transistors It is much easier to implement vertical transistor packing because source and drain areas can be arranged vertically. Reproducibility is difficult Difficulty in building up for carbon nanotube devices as opposed to the building down of silicon based devices.

Use in Transistors

Cedric (Stanford)

Use in Sensors Can be used as environmental sensors because they can change density and conductance properties depending on what they come into contact with Ammonia and Nitrogen Dioxide Sensors Hydrogen and Methane Sensors Sulfur Dioxide and Hydrogen Sulfide Sensors Carbon Monoxide Sensors O2 sensors Pressure Sensors

Use in Sensors Pressure sensors for robotics and medical field (Stanford) Variable capacitance and material elasticity

Other Applications Battery Technology (Stanford) Sacha (Stanford) Conductive Pastes Thermal clothing sensors for firefighters

Summary and Conclusions Scatter free current transport allowing high current densities and improved signal delays in transistors. Smaller feature size along with the ability to provide three dimensional stacking by implementing vertical gates and drains in transistors. Doping or coating allows for a variety of uses in gas sensor applications. Thin conductive layers can be produced for use in battery technology and pressure sensing.

References Hoenlein, W.; Kreupl, F.; Duesberg, G.S.; Graham, A.P.; Liebau, M.; Seidel, R.V.; Unger, E., "Carbon nanotube applications in microelectronics," Components and Packaging Technologies, IEEE Transactions on, vol.27, no.4, pp.629,634, Dec ^^^ Semiconductor characteristic charts for CNTs and Image of CNT Yonggang Zou; Guojun Liu; Lin Li; Zhanguo Li; Mei Li, "Carbon nanotubes and thermal properties," Laser Physics and Laser Technologies (RCSLPLT) and 2010 Academic Symposium on Optoelectronics Technology (ASOT), th Russian-Chinese Symposium on, vol., no., pp.72,75, July Aug Anas, N.S., "Carbon Nanotube as a basic material for Sensors: A review," Nanoscience, Engineering and Technology (ICONSET), 2011 International Conference on, vol., no., pp.212,218, Nov Sukirno; Bisri, Satria Zulkarnaen; Irmelia; Hasanah, L.; Suryamas, Adi Bagus; Usman, I.; Mursal, "Comparison of Electronic Transport Parameter of CNT(10,10)/CNT(17,0) and CNT(5,5)/CNT(8,0) Carbon Nanotube Metal-Semiconductor On-Tube Heterojunction," Semiconductor Electronics, ICSE '06. IEEE International Conference on, vol., no., pp.267,271, Oct Dec Bondar, A.M.; Bara, A.; Patroi, D.; Svasta, P.M., "Carbon Mesophase/Carbon Nanotubes Nanocomposite - Functional Filler for Conductive Pastes," Polymers and Adhesives in Microelectronics and Photonics, Polytronic, Polytronic th International Conference on, vol., no., pp.215,218, Oct Aliahmad, N.; Agarwal, M.; Shrestha, S.; Varahramyan, K., "Paper-Based Lithium-Ion Batteries Using Carbon Nanotube-Coated Wood Microfibers," Nanotechnology, IEEE Transactions on, vol.12, no.3, pp.408,412, May 2013 ^^^ Battery photo source

References Pressure Sensor Photo Cedric Photo Bike Photo us/bikes/model/tcr.advanced.sl.1/18724/76095/ Arc discharge Photo Sumio Iijima Photo

Questions What are carbon nanotubes? What determines if a nanotube has metallic or semiconductor properties? What must we do in order to use carbon nanotubes in gas sensors? What are some unique properties of carbon nanotubes? What is the major drawback for the use of carbon nanotubes in transistors?