Goals for Today: Syllabus Review Continue “Fundamental Nanoscience” Discussion Assignments
Nanoscale science and engineering here refer to the fundamental understanding and resulting technological advances arising from the exploitation of new physical, chemical and biological properties of systems that are intermediate in size, between isolated atoms and molecules and bulk materials, where the transitional properties between the two limits can be controlled. -Mike Roco (NSF) 2001
NanotechnologyHeirarchy • Bulk Chemistry/Materials (Chemistry & Physics accomplish the self-assembly) • Manufacturing (e.g. Intel) directed assembly • Nanomachines • Self Replicators (life?) Increasing Complexity (information, design)
Entering the Nanoscale Trouble Predicted Moore’s 1st Law 400 300 200 100 0 Chip Feature Size (nm) 1990 1995 2000 2005 2010 2015 Year
Technology: • Components are getting smaller and smaller. • Interconnections between components are getting smaller and smaller.
Nano-Scale Science Size matters. Properties of materials depend on their size. What’s so special? We don’t normally notice…
NanoScience Issues • Physical (e.g. surface effect) • Chemical (bonding) • Quantum Mechanical • Information/Design
Example: Gold Michigan Gold 0.5 mm Gold Crystal From Nevada http://www.minerslunchbox.com/eugene.htm The Space Window Washington National Gallery
WHY? Why does gold look like gold until the particles get to nanometer size, and then the properties change dramatically?
Physical Surface Area Effect? Gold Number of surface atoms = number of bulk atoms L Estimate: 6·2·L2 = 4·L3 – 6·2·L2 L = 6 L L N = L3 = 216
Chemistry Example: Carbon Diamond Graphite
Chemical Bonding is Vital • Hardest material • Abrasive • Transparent • Electrical insulator • Excellent thermal conductor • Optically isotropic • Soft material • Lubricant • Opaque • Electrical conductor • Thermal conductor • Highly anisotropic
Nanotubes C60 Buckyballs Nanocones NanoCarbon
Nanotechnology Examples: Scanning Electron Microscopy image of an individual multiwalled carbon nanotube contacted by four electric leads for resistivity measurements. www.europhysicsnews.com/full/ 09/article3/article3.html
A prototype of a carbon nanotube based display (Samsung Display Technology, courtesy of Y. Choi). www.europhysicsnews.com/full/ 09/article3/article3.html
Quantum Mechanics • Matter (electron) has wave properties • Waves are related to probability of where to find particle • In bound systems, particles have discrete states(think of electron orbitals in atoms) • Energy and other properties are quantized (think of energy levels in atoms)
Quantum Dot (Barrier Potential) Quantum dot pillars in semiconductor. L. P. Kouwenhoven “artificial atoms”
States, Energies, Transitions Allowed energy changes are quantized.
Quantum Applets • http://www.falstad.com/mathphysics.html
Double Barrier (Quantum Dots) Energy “Forbidden Region”
Bringing Barriers Together… • Changes energy levels (and device properties) • Changes electron states • Allows for tunneling These changes can cause old technologies to fail. Or: You can capitalize on these properties for new devices.
Tunnelling Passage of a particle from one “localized” area to another through a “forbidden” region. Application: Scanning Tunneling Microscopy Potential Problems: Electrons can “leak” to where they are not supposed to be.
Quantum Dot Tunneling? Electric Force Microscope images of Ge quantum dots on Si-on-insulator. Charge was deposited on upper right mesa and migrated to the lower left mesa in about an hour. (Univ. Wisconsin) (http://www.mrsec.wisc.edu/individ_nuggets/irg1/Electrical_Properties_of_Quantum_Dots.htm)
Assignment:Nano in the Home… Nanotechnology: The application of nanostructures into useful nanoscale devices.
Assignment For Next Time • Read Ratter & Rattner chapters 1 & 2 • Look over the brochure Nanotechnology: Shaping the World Atom by Atom. • Answer questions on hand-out • 1-2 pages • (use complete sentences, • good grammar, etc.) http://www.nano.mtu.edu/documents/IWGN.Nanotechnology.Brochure.pdf
Nano at Home Examples: • Special additive to clothing for non-stain and wrinkle-free • Nano-composite coating for tennis balls • Fluorescent lights (excitation of atoms) • Additives for sunscreens and cosmetics • Carbon nanotube additives to batteries • Latest generation of Intel chips Any pattern or gross categories you see?