Nanowires

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Nanowires

• Getting Connected

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What are Nanowires?

• Nanowires are usually small pieces of metal and
  semi-conducting silicon, that can carry current
  to and from devices

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Methods of Producing Nanowire

• Laser Assisted Catalytic Growth
• Simple Vapor Transport
• Block by Block Growth

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Laser Assisted Catalytic growth
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Laser Assisted Catalytic growth (cont.)

• High yields of relatively short nanowires
• Highly uniform yield in shape and size.
• Large amounts of catalytic metal impurities

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Simple Vapor Transport
Sold Ge and GeI2
Gold covered Silicon
GeI2 (g)
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Simple Vapor Transport

• Makes Large amounts of Nanowires
• Uses metals and metal salts at high temperatures
• Produces high yields, but with metal impurities.

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Block by Block Growth using hybrid pulsed laser
ablation/ chemical vapor deposition
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Block by Block (cont.)

• Similar to the Simple Vapor Transport method and
  the Laser assisted Catalytic growth methods
• Best yield of extremely precise nanowires

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Uses of nanowire
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Basic Circuitry

• Nanowires can be used to create
• P/N junctions
• Photoluminescence (PL)
• Logic and Memory Circuits

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P/N Junctions

• What is a P/N junction?
• Doping In Silicon Semiconductor.

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Photoluminescence

• Plagued by low emission of light
• Silicon Nanowires are coated with cubic-silicon
  carbide to triple the photoluminescence

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Logic and Memory Circuits

• Potential for high memory and logic densities
• Higher integration due to dynamic factors
• Smaller size prevents errors due to impurities
  and irregularities in the wires.

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Chemical Sensors

• High surface to Volume ratio
• Changes in surface produce changes in
  conductivity
• First sensor detected hydrogen gas.

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Conclusion

• What are Nanowires?
• Methods of Producing Nanowire
• Uses of nanowire and its potential

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Sources

• Wu, YiyingFan, RongYang, Peidong.Block-byBlock
  Growth of Single-Crystalline Si/SiGe Superlattice
  Nanowires.Nano Letters, Web release 2002
• Wu, Yiyung Yang, Peiding. Chem.
  Mater2000,12,605-607
• Duan, X Lieber, C. J.Am.Chem.Soc.
  2000,122,188-189
• Walter,E.C.Penner, R.M Liu,H Ng, K.H.
  Zach,M.P.Favier,F Surf.Interface
  Anal.2002, 34,409-412
• Cui,Yi Duan, X Hu, J Lieber,C.M. J. Phys.
  Chem. 2000,104,22
• Zhou,X.T. Zhang, H.Y.Peng,N.G.Shang,NWang, I
  Bello, C.S. Lee,S.T. Chem. Phys Letters
  2000,332,215-218
• Kovtyukhova,N.I.Mallouk,T.E.Chem.Eur. J.
  2002,8,19 pgs.4355-4363