Science and Technology of Nanostructures
Physics 805, Fall 2009
F. J. Himpsel
Syllabus, Info, Lecture Notes :
http://uw.physics.wisc.edu/~himpsel/Nano/lectures.htm
Nanotechnology in our Daily Life
Iridescent car paint: Based on interference colors
(like a butterfly, no bleaching after 5 years Miami)
Nanotechnology on our Desktops
Transistor
Hard Disk
Gate
Sensor
Source
Well
6 nm
Medium
Drain
Gate oxide
4 nm
Switching layer
5 nm
Magnetic grain
10 nm
Quantum Well Laser: Designing the Perfect Trap
6 nm : Optimum Thickness
Nanocrystals
Quantum effect: Crystal size determines the color
(blue-shifted when smaller)
When does silicon cease to be silicon?
The band gap of silicon nanoclusters
GaAs
Bulk Silicon
3 nm : Gap begins to change
Transistor
Gate Oxide
Power consumption by a leaky gate oxide:
A show-stopper for silicon technology?
Hard Disk Reading Head
5 nm
Optimum
How small is a Nanometer ?
Each panel
10x smaller
Each time
something
different
125 nm
Hewlett-Packard molecular memory
Two more
steps to
reach one
nanometer
1027
Universe (largest length)
The Sun is a billion times larger
than a human, and a nanometer is
10–3
mm
10–6
m
10–9
nm
10–35
a billion times smaller.
Planck Length (smallest length)
The Physicist’s View:
Fundamental Length Scales
Consider devices operating at room temperature. Their energy levels
have to be separated by more than the thermal energy kBT = 25 meV .
Convert this energy scale to a length scale by fundamental constants.
Quantum
Quantum Well:
Quantum Well Laser
Electric
Capacitor:
Single Electron Transistor
Magnetic
Magnetic Particle:
Data Storage Media
E1
E0
d
a = V1/3
Energy Levels
Charging Energy
Spin Flip Barrier
3h2/8m l2
2e2/ d
½ M2a3
l
l < 7 nm
d < 9 nm
a > 3 nm
Biological Length Scales in the Nanometer Range
DNA
Virus (TMV)
3.4 nm
pitch
300
nm
10 base
pairs
2 nm
11 nm
18 nm
This end is attached to another
muscle fiber, pulling it along .
Molecular Motor
Driven by the reaction
ATP  ADP + Energy
Walker = myosin, kinesin
Linear Motor (Muscle)
Vale and Milligan, Science 288, 88 (2000)
Rail = actin, tubulin =
part of a muscle fiber
Life-like Structures at a Surface
Wieczorek et al., Website
Electrolyte
Artificial
Membrane
Rotary generator =
Rotary motor in reverse
Water
Solid substrate
Bacteriorhodopsin as
light-driven proton pump
Converts ADP to ATP
Powered by proton pump
Cornell et al., Nature 387, 580 (1997); Tanaka & Sackmann, Phys. Stat. Sol. A 203, 3452 (2006).
Knitting
with
Polymers
In Pursuit of the Ultimate Storage Medium :
1 Bit = 1 Atom
Silicon Surface
CD-ROM
1.6 nm Track
10 m
10 nm
Density x 1 000 000
Speed versus Density
Shot noise speed limit
DNA
Density limit:
5x4 cell = 20 atoms/bit
• Speed is sacrificed as density increases (less signal per bit)
• Density is limited by coupling between bits (range ~4 atoms)
When will we be down to atoms ?
Using Moore's Law ...
250 Terabit/inch2
Year 2038
Nanotechnology: A Moving Target
nano
Lithography
nano + bio
nano + bio + info
Directed Assembly
Self-assembly
The Madison Discovery Institutes (Nano + Bio + Info)
"Disruptive Technologies"
Clayton Christensen
Harvard Business School
A business model for Nanotechnology ?
Start with niche applications,
then break into mass markets.