Introduction to Nanotechnology: What, Why and How bnl manchester Mark Tuominen, UMass, November 17, 2007

Nanotech: What?

1 nanometer = 1 billionth of a meter Nanotechnology Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nanometers, where unique phenomena enable novel applications. 1 nanometer = 1 billionth of a meter = 1 x 10-9 m nano.gov

How small are nanostructures? Single Hair Width = 0.1 mm = 100 micrometers = 100,000 nanometers ! 1 nanometer = one billionth (10-9) meter

Smaller still DNA 3 nanometers 6,000 nanometers Hair Red blood cell .

From DOE

A Few Nanostructures Made at UMass 100 nm dots 70 nm nanowires 200 nm rings 150 nm holes 18 nm pores 12 nm pores 14 nm dots 13 nm rings 25 nm honeycomb 14 nm nanowires

Nanotech: Why?

Example: Advancement of the iPod 10 GB 2001 20 GB 2002 40 GB 2004 80 GB 2006 160 GB 2007 Hard drive Magnetic data storage Uses nanotechnology!

Magnetic Data Storage A computer hard drive stores your data magnetically “Read” Head Signal “Write” Head current S N Disk N S 1 _ “Bits” of information direction of disk motion

Scaling Down to the Nanoscale Increases the amount of data stored on a fixed amount of “real estate” ! Now ~ 100 billion bits/in2, future target more than 1 trillion bits/in2 25 DVDs on a disk the size of a quarter, or all Library of Congress books on a 1 sq ft tile!

Why do we want to make things at the nanoscale? To make better and new products: smaller, cheaper, faster and more effective. (Electronics, catalysts, water purification, solar cells, coatings, medical diagnostics & therapy, etc) To introduce completely new physical phenomena to science, technology. (Quantum behavior and other effects.)

Nanotech: How? How to make nanostructures? How to characterize and test them?

Making Nanostructures: Nanofabrication Top down versus bottom up methods Lithography Deposition Etching Machining Chemical Self-Assembly

Nanostructures nanofilm, macroscale (3D) object or nanolayer (2D) height depth width nanoparticle, nanodot, quantum dot (0D) nanowire, nanorod, or nanocylinder (1D)

Nanofilms (making thin objects)

An Early Nanotechnologist?

Excerpt from Letter of Benjamin Franklin to William Brownrigg (Nov ...At length being at Clapham, where there is, on the Common, a large Pond ... I fetched out a Cruet of Oil, and dropt a little of it on the Water. I saw it spread itself with surprising Swiftness upon the Surface ... the Oil tho' not more than a Tea Spoonful ... which spread amazingly, and extended itself gradually till it reached the Lee Side, making all that Quarter of the Pond, perhaps half an Acre, as smooth as a Looking Glass....

CHALLENGE: How thick was the film of oil? ... the Oil tho' not more than a Tea Spoonful ... ... perhaps half an Acre CHALLENGE: How thick was the film of oil? Volume = (Area)(Thickness) V = A t t = V/A = 2 cm3 20,000,000 cm2 V = 1 teaspoonful A = 0.5 acre ~ 2 cm3 ~ 2,000 m2 = 0.0000001 cm = 1 x 10-7 cm = 1 x 10-9 m = 1 nanometer (nm) 20,000,000 cm2

An example of a FILM A monolayer NANOFILM (single layer of molecules) ~1 nm thick Langmuir film This is an example of SELF-ASSEMBLY

Langmuir-Blodgett Film Must control movable barrier to keep constant pressure multiple dips - multiple layers

Another film method, Thermal Evaporation sample QCM Vaporization or sublimation of a heated material onto a substrate in a vacuum chamber film vapor Au, Cr, Al, Ag, Cu, SiO, others Pressure must be held low to prevent contamination! vacuum ~10-7 torr source There are many other thin film manufacturing techniques resistive, e-beam, rf or laser heat source vacuum pump

Nanofilm by Electroplating V cathode anode CuSO4 dissolved in water Working Electrode (WE) Counter (CE) Cu(0) –> Cu2+ + 2e- "oxidation" If using an inert Pt electrode: 2 H2O –> O2 + 4H+ + 4e- "reduction" Cu2+ + 2e- –> Cu(0)

BREAK

Imaging Nanostructures Atomic Force Microscope (AFM)

"Optical Lever" for Profilometry laser . cantilever

"Optical Lever" for Profilometry Long light path and a short cantilever gives large amplification laser . cantilever

Atomic Force Microscope AFM Cantilever Chip AFM Instrument Head Atomic Force Microscope Laser Beam Path Cantilever Deflection

STM Image of Nickel Atoms

Lithography (controlling width and depth)

Mark Tuominen Mark Tuominen Lithography Mark Tuominen Mark Tuominen (Using a stencil or mask)

Photolithography for Deposition process recipe apply spin bake spin coating substrate spin on resist resist expose mask (reticle) exposed unexposed "scission" develop narrow line deposit liftoff

Lithography Patterned Several IBM Times Copper Wiring On a Computer Chip

Electron-Beam Lithography Polymer film Silicon crystal Nanoscopic Mask !

Self-Assembled Nanostructures and Lithography Based on Self-Assembly

Self Assembly

Diatoms sinancanan.net priweb.org

Gecko feet

Abalone

NANOFABRICATION BY SELF ASSEMBLY Diblock Copolymers Block “B” Block “A” PS PMMA ~10 nm Scale set by molecular size Ordered Phases 10% A 30% A 50% A 70% A 90% A

Versatile, self-assembling, nanoscale lithographic system CORE CONCEPT FOR NANOFABRICATION Deposition Template Etching Mask Nanoporous Membrane (physical or electrochemical) Remove polymer block within cylinders (expose and develop) Versatile, self-assembling, nanoscale lithographic system

Application examples: Nanoelectronics

Computer Microprocessor "Heart of the computer" Does the "thinking"

Making Small Smaller An Example: Electronics-Microprocessors microscale nanoscale macroscale ibm.com

Electronics Keep On Getting Better Moore's "Law": Number of Transistors per Microprocessor Chip intel.com

Hard Disk Drives - a home for bits Hitachi

Magnetic Data Storage ? N S ‘0’ N S S N S N ‘1’ Current Magnet with unknown magnetic state N S S N S Current N ‘1’

Binary Representation of Data only 2 choices one bit “1” or “0” two bits 00, 01, 10, 11 4 choices three bits 000, 001, 010, 011, 100, 101, 110, 111 8 choices n bits has 2n choices For example, 5 bits has 25 = 32 choices... more than enough to represent all the letters of the alphabet

Binary representation of lower case letters 5-bit "Super Scientist" code: ex: k = 01011 1 S N OR (Coding Activity: Use attractive and repulsive forces to "read" the magnetic data!)

Improving Magnetic Data Storage Technology The UMass Amherst Center for Hierarchical Manufacturing is working to improve this technology Granular Media Perpendicular Write Head Soft Magnetic UnderLayer (SUL) coil 1 bit Y. Sonobe, et al., JMMM (2006) • CHM Goal: Make "perfect" media using self-assembled nano-templates • Also, making new designs for storage

Electrodeposited Nanowires in a Nanoporous Polymer Template (Mask) nanowires in a diblock copolymer template nanoporous template Pulse reverse electrodeposition results in improved microcrystalline structure and improved magnetic properties (larger perpendicula magnetocrystalline anisotropy) 1x1012 wires/in2

Solar Cells Benefit: Sun is an unlimited source of electronic energy. Konarka

Electric Solar Cells Sunlight - + + - Made from single-crystal silicon wafers (conventionally) Sunlight wires - cross-sectional view “load” n-type silicon Voltage p-type silicon + + - Current The load can be a lamp, an electric motor, a CD player, a toaster, etc

Nanostructured Solar Cells Sunlight - “load” Voltage + Current More interface area - More power!

Nanotechnology R&D is interdisciplinary and impacts many applications Physics Chemistry Biology Materials Science Polymer Science Electrical Engineering Chemical Engineering Mechanical Engineering Medicine And others Electronics Materials Health/Biotech Chemical Environmental Energy Aerospace Automotive Security Forest products And others

Thanks for visiting UMass and learning about nanotechnology!