nanotechnology - wayne state universityglawes/nano.pdf · q: what is nanotechnology? narrow...

33
Nanotechnology Gavin Lawes Department of Physics and Astronomy

Upload: ngoxuyen

Post on 02-Jul-2018

228 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Nanotechnology Gavin Lawes

Department of Physics and Astronomy

Page 2: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Length scales (Part I)

10-10 m 10-5 m 105 m 1010 m 1 m

Earth-Moon distance 4x108 m (courtesy NASA)

Michigan width 2x105 m (courtesy Google)

Red blood cell 1x10-5 m (courtesy PBS)

Magnetic nanoparticle 5x10-9 m

Person 2m

Page 3: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Length scales (Part II)

10-3 m

10-9 m

10-7 m

10-5 m

10-1 m

10-3 m=1 mm

10-6 m=1 µm=1 (micron)

10-9 m=1 nm (nanometer)

Courtesy CSU Hayward

Head of a pin 1,000,000 nm

Thickness of a human hair: 100,000 nm

Courtesy Intel

Transistors 65 nm

Visible light 400 to 700 nm

Distance between atoms in a solid ~0.3 nm

Page 4: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Q: What is Nanotechnology?

Page 5: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Q: What is Nanotechnology?

A: Depends on who you ask.

Page 6: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center for Responsible Nanotechnology

Broad “Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nm.” -National Nanotechnology Initiative

We will follow the broad definition for nanotechnology, since we need to understand the properties of small objects before we can build machines from them.

Page 7: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

10-3 m

10-9 m

10-7 m

10-5 m

10-1 m

Optical microscopy

Electron microscopy

Nanotechnology

How can we see things on the nanoscale?

• The development of scanning probe techniques (STM, AFM) in 1981 revolutionized the imaging of nanoscale systems.

Page 8: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Scanning Electron Microscope

Sandia National Laboratory

Mite on a chip Attogram (10-18 g) scale

Courtesy H. Craighead, Cornell University

• Uses reflected electrons to image small objects.

Page 9: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Transmission Electron Microscope

5 nm

γ-Fe2O3 nanoparticles

TEM Philips CM10

Liver Cell University of New England

• Uses electrons passing through sample to image small objects

Page 10: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Scanning Tunneling Microscope

Courtesy Kiel University

Courtesy J.C.S. Davis, Cornell

STM Tip

Quantum Corral

Courtesy IBM

BiO planes in BSCCO

Page 11: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Atomic Force Microscope

Pictures courtesy P. Hoffmann, WSU

Silicon atoms

4 nm

AFM tip

• Images small objects by the mechanical response of a cantilever.

Page 12: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

What can nanotechnology do for us?

Biomedical New drug delivery systems. New imaging techniques. Better sunscreens.

Materials Science Stronger and lighter materials. Combining properties on the nanoscale. Stain resistant pants and better paints.

Computers Ultra-high density hard drives. Smaller transistors. New polishing methods using nanoparticle slurries.

Magnetic nanoparticle

Page 13: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Why do we need nanotechnology for these things?

1. Cells are a few microns in size, so nanometer sized objects can freely move through cell walls, into the cell nucleus.

2. Nanoparticles have a very large surface area, making them useful for applications relying on the interface between different materials.

3. Electronic components are already less than 100 nm; increasing their performance will rely on working at smaller length scales.

4. The physical properties of materials at small length scales is very different than in bulk.

Page 14: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

How do you make nanotechnology?

Page 15: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

30 nm lines 90 nm lines Courtesy IBM research

Lithography

Top-down approach • Like making a statue of an elephant: start with a big block of marble, and chip away everything that doesn’t look like an elephant.

Focused ion beam

Courtesy C. Kruse, Bremen

Page 16: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Expose resist to light using mask.

Chemically etch regions not protected by the resist.

Mask Resist Material

Remove portions of resist not exposed to light.

Page 17: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Bottom-up approach • Like making a statue of an elephant from Lego, if the Lego blocks were 1 nm across.

DNA

Courtesy NIH

Xenon atoms positioned using STM

Courtesy D. Eigler IBM

Page 18: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

DNA Tweezers

Courtesy B. Yurke, Bell Labs Courtesy C. Mirkin, Northwestern

Gold-polymer nanorods

(Self-assembly)

Page 19: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

How do things change on the nanoscale?

Page 20: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Mechanical properties change Silicon spur being broken

Courtesy J. Parpia, Cornell University

Page 21: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Courtesy UC Berkeley

Carbon nanotubes

Courtesy D. Ralph, Cornell University

Single electron transistor

Electronic properties change

Page 22: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Optical properties change

Courtesy Iowa State

CdSe Quantum (or Nano) Dots

Courtesy NYTimes

Medieval Stained Glass

Page 23: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Magnetic properties change

Courtesy Dataclinic.co.uk

20 nm

Iron oxide nanoparticles

• The magnetization direction of magnetic nanoparticles can change spontaneously at room temperature. This is bad for long-term magnetic storage.

Hard disk data sector

Page 24: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Dynamical properties change

Courtesy P. Keyes, WSU

Pollen grains in water

Courtesy P. Keyes, WSU

Simulation of Brownian Motion

• At small length scales, even individual collisions with water or air molecules can be important.

Page 25: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

At R=1 mm, A/V=3x103 m-1

At R=10 nm, A/V=3x108 m-1

Why does surface area matter for nanotechnology?

Factor of 105 difference!

Page 26: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Air resistance

The relative importance of drag forces increase as the surface to volume ratio, which becomes very large in nanoscale systems.

alt.

v

Page 27: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

% of Au atoms near surface Gold atoms are about 0.2 nm apart. What fraction of Au atoms are near the surface (2 layers away) in a 2 mm dia. gold ball? 20 nm dia. gold ball?

at R=1 mm, 1.2x10-4 % of atoms are near the surface.

at R=10 nm, 12 % of atoms are near the surface.

Page 28: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Surface loss mechanisms

Dissipative losses in small devices can be strongly affected by the motion of atoms and molecules bonded to the surface.

Courtesy H. Craighead, Cornell University

Cantilever • The dissipation in nanodevices can be reduced by over a factor of 10 by heating them to 1000 oC.

• This is important for removing molecules attached to the surface.

Page 29: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Nanoscale friction

Laws of Friction 1. The force of friction is directly proportional to the applied load. 2. The force of friction is independent of the apparent area of contact. 3. Kinetic friction is independent of the sliding velocity.

NB: Both of these have the same apparent area of contact, but the real area of contact is larger in the bottom case (under a larger normal load).

Page 30: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

200 um

Trailing clamp Leading clamp

Displacement gauge

Actuation Plate

Suspension spring

Courtesy A. Corwin, Sandia Labs

Inchworm actuator

A. Corwin et al, APL 84, 2451 (2004)

Interfacial adhesion changes frictional forces

Page 31: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Atomic scale friction

A. Socoliuc et al., Science 313, 207 (2006)

Commensurate surfaces higher friction

Incommensurate surfaces lower friction

Atomic scale friction

Page 32: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

Summary

• Recent scientific developments have spurred nanotechnology research.

• Things on small length scales often act very differently from things at larger length scales.

• This can be used to develop new applications for nanotechnology, but also leads to new types of problems to be addressed.

Page 33: Nanotechnology - Wayne State Universityglawes/nano.pdf · Q: What is Nanotechnology? Narrow “Nanotechnology is the engineering of functional systems at the molecular scale” -Center

End