Nanoscale Science and Technology I. Introduction

1. Nanoscale Science and Technology I. Introduction M. Meyyappan Director, Center for Nanotechnology NASA Ames Research Center Moffett Field, CA 94035 email: meyya@orbit.arc.nasa.gov web: http://www.ipt.arc.nasa.gov

2. Nanotechnology deals with the creation of USEFUL materials, devices and systems through control of matter on the nanometer length scale and exploitation of NOVEL phenomena and properties (physical, chemical, biological) at that length scale Nanometer • One billionth (10-9) of a meter • Hydrogen atom 0.04 nm Proteins ~ 1-20 nm Feature size of computer chips 180 nm Diameter of human hair ~ 10 µm

3. • Examples - Carbon Nanotubes - Proteins, DNA - Single electron transistors • Not just size reduction but phenomena intrinsic to nanoscale - Size confinement - Dominance of interfacial phenomena - Quantum mechanics • New behavior at nanoscale is not necessarily predictable from what we know at macroscales. AFM Image of DNA

4. What is Special about Nanoscale? • Atoms and molecules are generally less than a nm and we study them in chemistry. Condensed matter physics deals with solids with infinite array of bound atoms. Nanoscience deals with the in-between meso-world • Quantum chemistry does not apply (although fundamental laws hold) and the systems are not large enough for classical laws of physics • Size-dependent properties • Surface to volume ratio - A 3 nm iron particle has 50% atoms on the surface - A 10 nm particle 20% on the surface - A 30 nm particle only 5% on the surface

5. What is new about Nanoscience? • Many existing technologies already depend on nanscale materials and processes - photography, catalysts are “old” examples - developed empirically decades ago • In existing technologies using nanomaterials/processes, role of nanoscale phenomena not understood until recently; serendipitous discoveries - with understanding comes opportunities for improvement • Ability to design more complex systems in the future is ahead - designer material that is hard and strong but low weight - self-healing materials

6. • 1959 Feynman Lecture “There is Plenty of Room at the Bottom” provided the vision of exciting new discoveries if one could fabricate materials/devices at the atomic/molecular scale. • Emergence of instruments in the 1980s; STM, AFM providing the “eyes”, “fingers” for nanoscale manipulation, measurement… • Recently, there has been an explosion of research on the nanoscale behavior - Nanostructures through sub-micron self assembly creating entities from “bottom-up” instead of “top-down” - Characterization and applications - Highly sophisticated computer simulations to enhance understanding as well as create ‘designer materials’ STM Image of Highly Oriented Pyrolitic Graphite

7. • For information, www.nano.gov • Multiagency Initiative in nanotechnology starting in FY01 “National Nanotechnology Initiative (NNI) - Leading to the Next Industrial Revolution” • FY03 Nano budget is $679 M, representing 17% • Biggest portion of the funding goes to NSF - Followed by DoD, NASA, DOE, NIH - All these agencies spend most of their nano funding on university programs • Very strong activities in Japan, Europe, China, Singapore, fueled by Government Initiatives • Nano activities in U.S. companies: IBM, Motorola, HP, Lucent, Hitachi USA, Corning, DOW, 3M… - In-house R & D - Funding ventures • Nano Centers being established at Universities all across the world • Emerging small companies - VC funding on the increase

8. U.S. Europe Japan Synthesis & Assembly Biological Approaches & Application U.S./Eur Japan Dispersions and Coatings U.S./Eur Japan High Surface Area Materials U.S. Europe Japan Japan Europe U.S. Nanodevices Level 1 2 3 Highest Leadership Position • The U.S. does not dominate nanotechnology research. Nearly twice as much ongoing research overseas as in the U.S. In 1997 Govt. expenditures on Nanotechnology Research: U.S.: $118 M, Japan: $120 M, Europe: $122 M, Others: $65 M. • Many foreign leaders, companies, scientists believe that nanotechnology will be the leading technology of the 21st century. The fact that there is still a chance to get on the ground floor explains pervasive R & D worldwide. Strong nanotechnology programs in Singapore, Australia, Korea, Taiwan, China and Russia. Source: WTEC Report

9. • Academia will play key role in development of nanoscience and technology - Promote interdisciplinary work involving multiple departments - Develop new educational programs - Technology transfer to industry • Government Labs will conduct mission oriented nanotechnology research - Provide large scale facilities and infrastructure for nanotechnology research - Technology transfer to industry • Government Funding Agencies will provide research funding to academia, small business, and industry through the NNI and other programs (SBIR, STIR, ATP…) • Industry will invest only when products are within 3-5 years - Maintain in-house research, sponsor precompetitive research - Sponsor technology start-ups and spin-offs • Venture Capital Community will identify ideas with market potential and help to launch start-ups • Professional societies should establish interdisciplinary forum for exchange of information; reach out to international community; offer continuing education courses

10. Undergraduate Engineering Curriculum Before taking the bread and butter courses, the undergraduate training begins with: NOW SHOULD WE CONSIDER?

11. Undergraduate Curriculum • Should elective courses on nanotechnology be considered (one or two)? If so, coverage includes, but not limited to: - Bulk vs. nano properties - Introduction to synthesis and characterization - Examples of nanomaterials: tubes, wires, particles… - Surface phenomena - Quantum phenomena - Focus on emerging applications - ? • Summer internship and/or academic year co-op - National labs - Small and large companies with nano programs - University research • Degree in Nanotechnology? - Flinders University and University of New South Wales in Australia now offer B. Sc. in Nanoscience and Technology - Leeds University and Crane University in U.K. offer M. Sc. in Nanoscience and Technology - This, of course, has to be a university-wide effort with courses taught by Physical and Biological Sciences and Engineering Departments

12. “The emerging fields of nanoscience and nanoengineering are leading to unprecedented understanding and control over the fundamental building blocks of all physical things. This is likely to change the way almost everything - from vaccines to computers to automobile tires to objects not yet imagined - is designed and made.” - from IWGN Report Societal and Economic Benefits - Materials and Manufacturing - Nanoelectronics and Computing - Medicine and Health - Environment and Energy - Transportation - National Security - Aeronautics, Space exploration “As we enter the 21st century, nanotechnology will have a major impact on the health, wealth and security of the world’s people that will be at least as significant in this century as antibiotics, the integrated circuit, and man-made polymers.” - from IWGN Report

13. Nanoelectronics Sensors, NEMS Inorganic Organic Structural Applications Bio Nanotechnology R & D Materials Applications

14. Various Nanomaterials and Nanotechnologies • Nanotubes • Nanosprings • Nanobelts • Dendrimers • Molecular electronics • Quantum dots • NEMS, Nanofluidies • Nanocrystalline materials • Nanoparticles • Nanocapsules • Nanoporous materials • Nanofibers • Nanowires • Fullerenes

15. As Recommended by the IWGN Panel • Nanostructure Properties - Biological, chemical, electronic, magnetic, optical, structural… • Synthesis and Processing - Enable atomic and molecular control of material building blocks - Bioinspired, multifunctional, adaptive structures - Affordability at commercial levels • Characterization and manipulation - New experimental tools to measure, control - New standards of measurement • Modeling and simulation • Device and System Concepts - Stimulate innovative applications to new technologies

16. 1. What novel quantum properties will be enabled by nanostructures (at room temp.)? 2. How different from bulk behavior? 3. What are the surface reconstructions and rearrangements of atoms in nanocrystals? 4. Can carbon nanotubes of specified length and helicity be synthesized as pure species? Heterojunctions in 1-D? 5. What new insights can we gain about polymer, biological…systems from the capability to examine single-molecule properties? 6. How can one use parallel self-assembly techniques to control relative arrangements of nanoscale components according to predesigned sequence? 7. Are there processes leading to economic preparation of nanostructures with control of size, shape… for applications?

17. • Ability to synthesize nanoscale building blocks with control on size, composition etc. further assembling into larger structures with designed properties will revolutionize materials manufacturing - Manufacturing metals, ceramics, polymers, etc. at exact shapes without machining - Lighter, stronger and programmable materials - Lower failure rates and reduced life-cycle costs - Bio-inspired materials - Multifunctional, adaptive materials - Self-healing materials • Challenges ahead - Synthesis, large scale processing - Making useful, viable composites - Multiscale models with predictive capability - Analytical instrumentation

18. • Carbon Nanotubes • Nanostructured Polymers • Optical fiber performs through sol-gel processing of nanoparticles • Nanoparticles in imaging systems • Nanostructured coatings • Ceramic Nanoparticles for netshapes Source: IWGN Report

19. More Examples of Nanotech in Materials and Manufacturing • Nanostructured metals, ceramics at exact shapes without machining • Improved color printing through better inks and dyes with nanoparticles • Membranes and filters • Coatings and paints (nanoparticles) • Abrasives (using nanoparticles) • Lubricants • Composites (high strength, light weight) • Catalysts • Insulators

20. Example of Self-Healing Material ‘Self-healing plastic’ by Prof. Scott White (U. of Illinois) Feb. 15, 2001, Issue of Nature • Plastic components break because of mechanical or thermal fatigue. Small cracks  large cracks  catastrophic failure. ‘Self-healing’ is a way of repairing these cracks without human intervention. • Self-healing plastics have small capsules that release a healing agent when a crack forms. The agent travels to the crack through capillaries similar to blood flow to a wound. • Polymerization is initiated when the agent comes into contact with a catalyst embedded in the plastic. The chemical reaction forms a polymer to repair the broken edges of the plastic. New bond is complete in an hour at room temperature.

21. Nanoelectronics and Computing Past Shared computing thousands of people sharing a mainframe computer Present Personal computing Future Ubiquitous computing thousands of computers sharing each and everyone of us; computers embedded in walls, chairs, clothing, light switches, cars….; characterized by the connection of things in the world with computation.

22. “There is at least as far to go (on a logarithmic scale) from the present as we have come from ENIAC. The end of CMOS scaling represents both opportunity and danger.” -Stan Williams, HP • 4-8 CMOS generations left but cost of building fabs going up faster than sales. Physics has room for 109x current technology based on 1 Watt dissipation, 1018 ops/sec no clear ways to do it! - Molecular nanoelectronics - Quantum cellular automata - Chemically synthesized circuits • Self assembly to reduce manufacturing costs, defect tolerant architectures are critical to future nanoelectronics

23. 1938 1998 Technology engine: Vacuum tube Proposed improvement: Solid state switch Fundamental research: Materials purity Technology engine: CMOS FET Proposed improvement: Quantum state switch Fundamental research: Materials size/shape • Quantum Computing - Takes advantage of quantum mechanics instead of being limited by it - Digital bit stores info. in the form of ‘0’ and ‘1’; qubit may be in a superposition state of ‘0’ and ‘1’ representing both values simultaneously until a measurement is made - A sequence of N digital bits can represent one number between 0 and 2N-1; N qubits can represent all 2N numbers simultaneously • Carbon nanotube transistor by IBM and Delft University • Molecular electronics: Fabrication of logic gates from molecular switches using rotaxane molecules • Defect tolerant architecture, TERAMAC computer by HP architectural solution to the problem of defects in future molecular electronics - Stan Williams

24. Expected Nanotechnology Benefits in Electronics and Computing • Processors with declining energy use and cost per gate, thus increasing efficiency of computer by 106 • Higher transmission frequencies and more efficient utilization of optical spectrum to provide at least 10 times the bandwidth now • Small mass storage devices: multi-tera bit levels • Integrated nanosensors: collecting, processing and communicating massive amounts of data with minimal size, weight, and power consumption • Quantum computing • Display technologies

25. • Expanding ability to characterize genetic makeup will revolutionize the specificity of diagnostics and therapeutics - Nanodevices can make gene sequencing more efficient • Effective and less expensive health care using remote and in-vivo devices • New formulations and routes for drug delivery, optimal drug usage • More durable, rejection-resistant artificial tissues and organs • Sensors for early detection and prevention Nanotube-based biosensor for cancer diagnostics

26. • DNA microchip arrays using advances for IC industry • ‘Gene gun’ that uses nanoparticles to deliver genetic material to target cells • Semiconductor nanocrystals as fluorescent biological labels Source: IWGN Report

27. Benefits of Nanotechnology in Transportation • Thermal barrier and wear resistant coatings • High strength, light weight composites for increasing fuel efficiency • High temperature sensors for ‘under the hood’ • Improved displays • Battery technology • Automatic highways • Wear-resistant tires

28. • Nanotechnology has the potential to impact energy efficiency, storage and production • Materials of construction sensing changing conditions and in response altering their inner structure • Monitoring and remediation of environmental problems; curbing emissions; development of environmental friendly processing technologies • Some recent examples: - Crystalline materials as catalyst support, $300 b/year - Ordered mesoporous material by Mobil oil to remove ultrafine contaminants - Nano-particle reinforced polymers to replace metals in automobiles to reduce gasoline consumption

29. Some critical defense applications of nanotechnology include • Continued information dominance: collection, transmission, and protection • High performance, high strength, light weight military platforms while reducing failure rates and life cycle costs • Chemical/biological/nuclear sensors; homeland protection • Nano and micromechanical devices for control of nuclear and other defense systems • Virtual reality systems based on nanoelectronics for effective training • Increased use of automation and robotics

30. • Advanced miniaturization, a key thrust area to enable new science and exploration missions - Ultrasmall sensors, power sources, communication, navigation, and propulsion systems with very low mass, volume and power consumption are needed • Revolutions in electronics and computing will allow reconfigurable, autonomous, “thinking” spacecraft • Nanotechnology presents a whole new spectrum of opportunities to build device components and systems for entirely new space architectures - Networks of ultrasmall probes on planetary surfaces - Micro-rovers that drive, hop, fly, and burrow - Collection of microspacecraft making a variety of measurements

31. Assessment of Opportunities • Lots of nanoscience, little nanotechnology • Short term (< 5 years) - CNT based displays - Nanoparticles * Automotive industry (body moldings, timing belts, engine covers…) * Packaging industry - CNT-based probes in semiconductor metrology - Coatings - Tools - Catalysts (extension of existing market)

32. Assessment of Opportunities (Cont.) • Medium term (5-15 years) - Memory devices - Fuel cells, batteries - Biosensors (CNT, molecular, qD based) - Advances in gene sequencing - Advances in lighting • Long term (> 15 years) - Nanoelectronics (CNT) - Molecular electronics - Routine use of new composites in Aerospace, automotive (risk-averse industries)

33. Revolutionary Technology Waves Red Herring, May 2002 Commonality: Railroad, auto, computer, nanotech all are enabling technologies

34. Percentage of Surface Atoms Source: Nanoscale Materials in Chemistry, Wiley, 2001

35. Melting Point of Gold Particles The melting point decreases dramatically as the particle size gets below 5 nm Source: Nanoscale Materials in Chemistry, Wiley, 2001

36. Some More Size-Dependent Properties • For semiconductors such as ZnO, CdS, and Si, the bandgap changes with size - Bandgap is the energy needed to promote an electron from the valence band to the conduction band - When the bandgaps lie in the visible spectrum, changing bandgap with size means a change in color • For magnetic materials such as Fe, Co, Ni, Fe3O4, etc., magnetic properties are size dependent - The ‘coercive force’ (or magnetic memory) needed to reverse an internal magnetic field within the particle is size dependent - The strength of a particle’s internal magnetic field can be size dependent

37. Nanoporous Materials • Zeolite is an old example which has been around a long time and used by petroleum industry as catalysts • The surface area of a solid increases when it becomes nanoporous; this improves catalyst effects, adsorption properties • ‘Adsorption’ is like ‘absorption’ except the absorbed material is held near the surface rather than inside • How to make nanopores? - lithography followed by etching - ion beam etching/milling - electrochemical techniques - sol-gel techniques