Nanotechnology: Opportunities and Challenges

1
Nanotechnology Opportunities and Challenges

• Chennupati Jagadish
• Australian National University
• Research School of Physics and Engineering
• Canberra
• c.jagadish_at_ieee.org

2
Overview

• What is Nanotechnology?
• Why Nanotechnology is Important?
• How to Make Nanostructures?
• Some Examples of Nanotechnology
• Nanowires
• Quantum Dots
• ARCNN
• ANFF
• Summary

3
Nanotechnology Engineering at the Atomic and
Molecular Scale

• One billionth of a metre
• A human hair 80 000nm wide
• A red blood cell 7 000nm wide

4
Why Nanomaterials ?
Large Surface to Volume Ratio (Catalysts,
sensing, hydrogen storage) CNTs- lightweight,
high strength
Nanostructured surface
Quantum Size Effects (solar cells, displays,
electronics,photonics)
Colloidal CdSe quantum dots
5
Why is the nano-scale interesting?

• Living things are assembled from nano-scale
  components
• A major question addressed by nano-science is can
  we learn to use natures fabrication methods?
• Smaller things generally provide enhanced
  performance- Faster computer chips, higher memory
  density, Faster Communications, Higher Efficiency
• Completely new phenomena can be produced in
  nanoscale materials- Colour without pigments

6
From lotus leaf to lifestyles

• Copy the surface to create water-repellent
  self-cleaning surfaces
• Water proofing
• Fabric, chrome, windows

Surface of a lotus leaf
Paint that self cleans with rainfall
7
Widespread Application Areas for Nanotechnology
Medicine and Health
InformationTechnology
New Materials
Food, Water and the Environment
Instruments
Energy Production / Storage
GMR Hard Disk
Hydrogen Fuel Cells
Lightweight strong matls.
Drug delivery
Remediation methods
Tunneling microscopy
Molecular Switches
City-Sized Skyscrapers
Solar Cells
Nano Manipulators
Smart Membranes
Treatments for Cancer
Expected to impact virtually all technological
sectors as an enabling or key technology
Clayton Teague, In part from R. Tomellini
8
Potential revenue 2014

• 15 of global manufacturing output
• US2.6 trillion

Sales of products using emerging nanotechnologies
ICT combined
Nano
Biotech
Source Lux Research, Sizing Nanotechnologys
Value Chain, 2004
9
(No Transcript)
10
Longer life tennis balls

• Wilson Double Core tennis ball
• A nanocomposite material
• Diverse applications-
• Air-tight food packaging, protective gloves

Outside
Pressurised air inside tennis ball
11
Nano-Electronics

• Leap in computer technology
• Hewlett-Packard Feb 2005
• Molecular scale version of the transistor
• Next Generation
• computing

10-1
10-4
10-5
10-6
10-6
10-9
12
Nanotechnology is DevelopingSelected High
Technology products
In vivo imaging of same area with conventional
methods at same depth with five times the
illuminating power
In vivo imaging of vasculature of mouse with
quantum dots
in vivo imaging through skin of mice for dynamic
angiography of mice From D.R. Larson, et al.
Science, 2003, 3001434-1436
Biocompatible nanomaterial bone screws Bone
bonding in 2 weeks and osseo-integration in 4
weeks
Quantum dot labeling for tracking five cellular
components
13
Diagnosis Treatment of Cancer
Using Nanotechnology to Advance Cancer
Diagnosis, Prevention and Treatment
National Cancer Institute (NIH)
From NCI R. Koperman
Nanotechnology will change the very foundations
of cancer diagnosis and treatment.
14
Water and EnergyRoles of nanomaterials

• Water
• Desalination (nanofilters), water reuse and
  recycling (photocatalysis)
• Energy
• Photovoltaics
• Thermoelectrics
• Hydrogen separation membranes / H2 Storage
• Photocatalysts
• Materials for fuel cells and supercapacitors
• Solid State Lighting

15
Gas Separation Membranes
US DOE FutureGen
Hydrogen Economy
16
Nanostructured Hydrogen Storage Materials
L. Schlapbach and A. Züttel, Nature, Vol. 414,
353-358, 2001
Containers storing 4kg H2 compared to size of a
car
Ads-H2 (5-10wt)

• Liquefying hydrogen wastes at ca. 1/ 3 of the
  stored energy
• Chemical hydrides suffer from weight and cost
  concerns
• Compressed tanks have issues of volume and
  safety

17
Single-Wall Carbon Nanotubes

• Hydrogen storage capacity around 4 wt at ambient
  temperature and moderate pressure
• Low cost high volume fabrication processes are
  not yet available for carbon nanotubes
• We need 8 wt storage capacity

C. Liu, Y.Y. Fan, M. Liu, H.T. Cong, H.M. Cheng,
and M.S. Dresselhaus, Hydrogen Storage in
Single-Walled Carbon Nanotubes at Room
Temperature, Science, 286, 1127-1129 (1999).
From Patrovic Milliken (2003)
18
Proton Exchange Membrane Fuel Cell (PEMFC)
(Solid Electrolyte)
Nafion PEM Alternatives Nanoparticle embedded
conducting polymers
Pt nanoparticle catalyst Porous Carbon Fiber
Electrodes
19
High Efficiency, Inexpensive Solar Cells
A grand challenge in energy research Harvesting
of solar energy with 20 efficiency at cost of
1/m2 Todays SOA is 14 at 100/m2
GaAs Nanowires Grown at ANU
From P. Alivisatos, U. of California and Lawrence
Berkeley National Laboratory
20
Supercapacitors
Supercapacitor Applications
Power density
Capacitor replacements
Energy density
21
High Performance Batteries For Electric Autos
Plug-in Hybrids or Total Electric
20-30 nm particles aggregated into 1-5 mm
particles
Anode - Nano LiTiO spinel
Cathode- Nano LiMnO spinel
Based on New Nano-Structured Materials Range 350
km Recharge Time 3 minutes
22
Lightweight Transportation Vehicles for Improved
Energy Efficiency
Lightweight Magnetic and Structural Nanomaterials
The challenge Low price MWCNT 25/g
250/kg High purity SWCNTs gt 1million/kg To be
considered for light weight automobiles, need
4/kg
23
World at Night
In the US, about 20 of electricity usage is for
lighting Each percent reduction in electricity
usage gt five 1 GW power plants not needed
24
200-year Evolution of Luminous Efficacy for
Various Lighting Technologies
Doubling efficiency from 25 to 50 ? Reduction
of power equivalent to output of 50 one-GW power
plants in USA
25
White LEDsGaN, InN, AlN, Nanophosphors, Photonic
Crystals, Quantum Dots
26
How to Make Nanostructures?

• Top down approach carve them from big objects
• Method used to make silicon chips
• Applicable over scale from mm down to 10nm
• Bottom up approach assemble objects atom by atom
• Can create new structures, new properties
• Process used in Nature
• Could lead to self replicating systems
• Scale lt1nm to 100s µm

27
Top down The silicon chip
The wafer
The circuit
The devices
The nanosize increases the speed of computers-
Moores Law 90 nm feature sizes moving towards 20
nm in the next decade
28
Electron Beam Lithography(top down approach)
29
Photonic Crystals
Photonic Crystal Based Optical Circuits
30
Carbon Nanotube
CNT is a tubular form of carbon with diameter as
small as 1 nm. Length few nm to microns. CNT
is configurationally equivalent to a two
dimensional graphene sheet rolled into a tube.
CNT exhibits extraordinary mechanical properties
Youngs modulus over 1 Tera Pascal, as stiff as
diamond, and tensile strength 200 GPa. CNT can
be metallic or semiconducting, depending on
chirality.
31
Carbon nanotubes how do we make them?
rotate

• Ball milling to give nanoparticles

• Heat to grow nanotubes

100 nm
1000 nm
32
Types of nanotubes

• Single and multiwalled
• tubes

• Bamboo tubes

20 nm
33
CNT Applications Electronics
CNT quantum wire interconnects Diodes and
transistors for computing Capacitors Data
Storage Field emitters for instrumentation F
lat panel displays THz oscillators
Challenges
Control of diameter, chirality Doping,
contacts Novel architectures (not CMOS
based!) Development of inexpensive
manufacturing processes
34
Nanotubes what can they be used for?

• Flat panel displays

35
Nanowires as Building Blocks for Electronics and
Photonics
substrate
LEDs, Lasers Single Electron Transistors Photodete
ctors Bio-sensors
Future nanowire OEIC
36
III-V nanowires
1 µm
1 µm
AlGaAs (111) nanowires
GaAs (111) nanowires
(Zinc Blende- Cubic)
20 nm
InP
1 µm
1 µm
InAs and InP nanowires (Wurtzite-Hexagonal)
37
Radial heterostructure nanowires

• Low temperature ? axial nanowire growth (GaAs
  core at 450 ºC)
• High temperature ? radial shell growth (AlGaAs
  shell at 650 ºC)
• GaAs core passivated by AlGaAs shell
• enhanced PL (excitonic emission 1.515 eV)

AlGaAs shell
GaAs shell (quantum well)
AlGaAs shell
GaAs core
1 µm
GaAs cores

• Blue-shifted PL peak from GaAs/AlGaAs
  core-multishell structures
• Quantum well shells? Or AlGaAs related emission
  more likely!!!!
• L. Titova et al. Appl. Phys.Lett. 89, 172326
  (2006)

38
Axial heterostructure nanowires

• Axial heterostructure segments grown by switching
  gas flows, eg. switching on TMG and switching
  on/off TMI
• Growth interrupt of between 1 and 5 minutes, to
  deplete the Au particle of the previous group III
  species
• Thin axial segments ? axial quantum wells
• Diffusion of adatoms from the substrate is a
  confounding factor and difficult to predict QW In
  Composition

• Indium incorporation towards the base when TMI is
  introduced
• Kinking occurs with Smaller Au particles Higher
  TMI flow

substrate
39
Ordered Nanowires(Single Photon Sources, QD
lattices, Photonic Crystals, NW-Organic Solar
Cells)
40
InGaAs Quantum Dots-Amount of Material
6.5ML
5.8ML
5ML
4ML
ML Monolayer 0.28 nm Typical Size width
20-30 nm, height 4-5 nm
41
Multi-Wavelength QD Lasers
Lasing spectra of devices fabricated from QDs
grown in regions without SiO2 and between
stripes of width 5µm and 10µm. The opening
between the stripes is 50µm. S. Mokkapati, H.H.
Tan and C. Jagadish, Appl. Phys. Lett 90, 171104
(2007)
42
Quantum Dot Infrared Photodetectors
Night Vision
Medical Imaging
Manufacturing
43
Quantum Dot Infrared Photodetectors

• Grown by MOVPE
• 10 Stacked dot layers
• Wide GaAs spacer layer ? reduced dark current
• Top and bottom Si doped layers for contacts

V
S.I. GaAs
44
Quantum Dot Infrared Photodetector Detectors
(QDIPs)
X-TEM of 10-layer In0.5Ga0.5As/GaAs QDIP structure
Spectral response for 10-layer QDIPs
45
Schematic of a typical QD solar cells
46
InGaAs Quantum Dot Solar Cells_at_ANU
I-V characteristics under light illumination
(un-calibrated)
Quantum efficiency
47
Members
ARC Nanotechnology Network
Currently ARCNN has more than 210 Nanotechnology
Research Groups comprised of 1050 individual
ARCNN Members, including

• Researchers from Univs, CSIRO,
• ANSTO, DSTO,
• Members from Industry
• 430 PhD Students
• 220 Early Career Researchers
• 50 International Researchers
• Canada, France, Germany, Korea, The Netherlands,
  New Zealand, USA

www.ausnano.net
Approx
Membership is FREE, Pl. Join
48
ARC Nanotechnology Network
Supported Activities

• Conferences, Workshops, Summer Schools
• Short Term and Long Term Visits
• Distinguished Lecturer Visits
• Overseas Travel Scholarships
• Young Nano Ambassadors
• Outreach (Newsletters, NanoQ, Public Lectures)
• Facilities and Infrastructure Database
• National and International Linkages
• ICONN 2010 Feb 22-26, 2010, Sydney

www.ausnano.net
49
Australian National Fabrication Facility ACT Node
(NCRIS)Australian National University and
University of Western Australia

• To Establish and Provide Access to State of the
  Art Micro and Nano Photonics Facilities to the
  Australian Research Community
• Compound Semiconductors (III-V, II-VI),
  Chalcogenide Glasses
• Ion Implantation and Ion Beam Analysis
• Electrical, Optical and Structural
  Characterisation
• Lasers, Photodetectors, Solar Cells, Integrated
  Optoelectronics, Non-linear Optical Devices
• Low Temperature MEMS Technology
• Infrared Detector Technology
• GaN HEMT Technology

50
Summary

• Nanotechnology is multidisciplinary
• It is an enabling technology with great
  implications for the society
• Nanotechnology offers exciting Science and
  Engineering Challenges
• Engaging Public and Addressing Public Concerns is
  important
• Environmental, Toxicological Effects and Ethical
  issues need to be considered