Molecular Electronics

1
Molecular Electronics

• Engineering Frontiers
• Spring 2001
• Wayne Doran

2
Background

• 1989 25 MHz Computers
• Today Pentium IV 1.4 GHz
• Remarkable, but predicted
• Moores Law
• Continuously making transistors smaller
• How much longer will it continue?

3
Background

• Problems with small (lt .1 ?m) transistors
• High concentrations of dopants
• Inaccurate optical lithography
• Heat dissipation
• Stray signals

4
Background

• Biggest barrier to small transistorsECONOMICS!
• Every time someone does a study on when we will
  hit those scientific limits, we dont ever hit
  them. We hit the other, more important,
  financial barriers. -Chief technologist at IBM
• Estimated cost of silicon chip fabrication plant
  in 2015 200 Billion

5
Background

• Huge demand for smaller, faster, and cheaper
  chips
• Silicon is not going to meet these demands
  forever
• Other alternatives to present day semiconductors
• Biocomputing
• Optical electronics
• Molecular Computers

6
Molecular ElectronicsWhat are they?

• Electronics made out of molecules
• Groups of molecules that perform tasks identical
  to those of semiconductors
• Transistors
• Diodes
• Memory
• Conductors

7
Why Use Them?

• Small!
• A billion trillion individual molecules in a drop
  of water
• Consume Less Power
• Cheap
• Eliminate expensive semiconductor fabrication
  plants

8
How They Work

• Electrons arrange themselves as bonds among atoms
  (clouds or orbitals)
• Orbitals overlap Electrons Flow
• Molecular Wire
• Chain of molecules with overlapping orbitals
• Molecular Switch
• Allows current to flow, or stops current based on
  electric field

9
Molecular Switch

• Bezene ring molecular Switch

10
Challenges

• Building the next transistor
• Combining todays semiconductors with molecular
  devices
• Random defects
• Addressing

11
Principle Players

• Rice University James Tour
• Yale University Mark Reed
• HP UCLA
• First molecular switch
• Harvard
• IBM

12
Whos Going to Win the Race?

• Striving for the first molecular transistor
• Potentially a history making event
• Bell Labs and the first transistor

13
Impacts

• Engineers Scientists
• New possibilities
• End User
• Might not realize scientific significance
• Will realize
• Cheaper, smaller, faster electronics

14
Market Impacts

• Business side
• Next 5 years
• Wont see any products on the market
• Long term (15-20 years)
• Miniature computers more powerful than todays
  desktops
• Nano-robots

15
Summary

• Important for engineers to be familiar with
  Molecular Electronics
• What does the future hold?
• Signs of success?