Carbon Nanotube Inter and Intramolecular Logic Gates

1
01010101010100101010101010101010101001010101001000
01010010001001010010100101010101010101010100101010
10101010101010010101010101010101000010101000010100
10100001010001010000010001001010010001010010010001
00100010000000100101010100101010000100101001001100
10101001000101000101001010100101010010001010100101
01010101010100101010101010101010101010101010101010
10101010101010101010101010101001010101010101010000
01010101010101010101001010100101010101010000010010
10100001010000100100101000010010101010001001010010
01010101010010000101000101000001000100101001000101
00100100010010001000000010010101010010101000010010
10010011001010100100010100010100101010010101001000
10101001010101010101010010101010101010101010101010
10101010101010101010101010101010101010100101010101
01010101010010101010101010101010010101010101010101
00001010100001010010100001010001010000010001001010
01000101001001000100100010000000100101010100101010
00010010100100110010101001000101000101001010100101
01001000101010010101010101010100101010101010101010
10101010101010101010101010101010101010101010101001
01010101010101000001010101010101010101001010100101
01010101000001001010100001010000100100101000010010
10101000100101001001010101010010101000010010100100
11001010100100010100010100101010010101001000101010
01010101010101010010101010101010101010101010101010
10101010101010101010101010101010100101010101010101
00000101010101010101010100101010010101010101000001
00101010000101000010010010100001001010101000100101
00100101010101001000010100010100000100010010100100
01010010010001001000100000001001010101001010100001
00101001001100101010010001010001010010101001010100
10001010100101010101010101001010101010101010101010
10101010101010101010101010101010000100101000101001
01001010101010101000010010000101010100101010101010
10101010000100010010001010010100001010101000110001
2
Carbon NanotubeInter- and Intramolecular Logic
Gates
By V. Derycke, R. Martel, J. Appenzeller and Ph.
Avouris
Presented by Anthony Hargrave
3
What is a Logic Gate?

• A circuit taking in at least one input and
  producing an output based on the gate type
• Building blocks of computers
• Only three basic types needed to create anything

4
Basic Logic Gates

• AND OR NOT

A
A
B
B
5
NOT Gate
6
P-Type vs N-TypeSemiconductors

• P-Type Uses electron holes as the conduit for
  current to pass
• N-Type Uses extra electron to allow current flow

7
Moores Law
Doubling number of transistors on a chip every
year Doubling data density every 18 months New
transistor fabrication methods needed
8
What are Carbon Nanotubes?

• Rolled-up monolayer of graphite
• Two main groups
• Metallic
• Semiconducting

9
Carbon Nanotubes
10
Creating Voltage Inverters

• To create voltage inverters, or NOT logic gates,
  both p-type and n-type carbon nanotubes are
  needed
• Since all carbon nanotubes all begin as p-type,
  two methods of conversion were found.

11
First Conversion Method

• The first process for converting the p-type
  nanotubes to n-type nanotubes is annealing in a
  vacuum
• Can be reversed by oxygen transferring its
  electric charge to the nanotubes

12
Oxygen Problem

• With oxygen shifting n-type nanotubes back to
  p-type, they couldnt be used in the open air of
  a computer
• A solution was fortunately already on hand
• Polymethyl-methacrylate (PMMA)
• This coating not only added stability and
  environmental protection but kept out the oxygen
  as well

13
Intermolecular NOT Gate
14
Second Conversion Method

• The second process found for converting p-types
  to n-types is Potassium doping
• Spatially selective doping can be used to convert
  only part of a nanotube to n-type

15
Intramolecular NOT Gate
16
Into the Future

• Nanotube based logic gates
• smaller size
• less power consumption
• less energy lost as heat

17
BONUS INFO!

• Carbon Nanotubes as
• Tethers with a diameter 10 nanometers, per
  kilogram of mass, a nanotube theoretically will
  be over 30 times as strong as Kevlar and 250
  times as strong as steel.
• http//www.isr.us/Downloads/niac_pdf/definitions.h
  tml
• Quantum Wires conduct electricity 10 times
  better than copper and weigh 1/6 as much
• http//www.netcomposites.com/news.asp?2960

18
Special Thanks To

• Dr. Leopold
• Dr. Shaw