Nanomaterials and
Nano-structures
for Electronic Applications
Dr. Chacko Jacob
Associate Professor
Materials Science Centre
and
Advanced Technology Development Centre
IIT
Kharagpur
WHICH NANO?
TATA Nano
http://tatanano.inservices.tatamotors.com
NanoNuno®
http://www.coolest-gadgets.com/20060915/n
anonuno%C2%AE-umbrella-its-always-dry/
iPod Nano
www.apple.com/ipodnano/
PaperPro Nano
www.paperpro.com
Logitech VX Nano
http://www.techgadgets.in/wireless/2007/19/
logitech-vx-nano-cordless-laser-mouse-unveiled-in-india/
Nanotechnology Defined
“The development and use of devices that have a size of only a few
nanometres.” physics.about.com
“Research and technology development at the atomic, molecular or
macromolecular level in the length scale of approximately 1 - 100 nm range,
to provide a fundamental understanding of phenomena and materials at the
nanoscale and to create and use structures, devices and systems that have
novel properties and functions because of their small and/or intermediate
size.” www.nano.gov
“Branch of engineering that deals with things smaller than 100 nm
(especially with the manipulation of individual molecules).”
www.hyperdictionary.com
“Nanotechnology, or, as it is sometimes called, molecular manufacturing, is
a branch of engineering that deals with the design and manufacture of
extremely small electronic circuits and mechanical devices built at the
molecular level of matter.” www.whatis.com
“The art of manipulating materials on an atomic or molecular scale
especially to build microscopic devices.” Miriam Webster Dictionary
WHY NANO?
SA/V [m-1]
Skyscraper
4.2 × 10-2
Person
42
Small Machine part
6000
Nano-cube
6 × 109
OBSERVATION #1: Surface Area
becomes relatively more important
(compared to Volume) the smaller
things become!
WHY NANO?
How many atoms are there in a nano-cube (10-9 m on an edge)?
3
10-9
m
= 103 or 1000 atoms, with about 600 at the surface!
10-10 m
Likely not enough atoms to preserve compete bulk behavior.
OBSERVATION #2: Just making an object smaller will not give you a device
with the same behavior (i.e., the same chemistry or physics).
Melting, heat conduction, electrical conductivity, chemical reactivity, color,
other optical properties,…all can change as we move into the nano-world
(change compared with the micro- and everyday worlds).
Perspective of Length Scale
Top Down
1 km
1m
Aircraft Carrier
Boeing 747
Car
Humans
Laptop
Butterfly
Size of a Microprocessor
1 mm
Gnat
1 µm
Biological cell
Nucleus of a cell
Wavelength of Visible Light
Smallest feature in microelectronic chips
Resolving power of the eye ~ 0.2 mm
Micromachines
Nanostructures & Quantum Devices
Bottom Up
1 nm
Proteins
Width of DNA
Size of an atom
electron
neutron
proton
http://www.dod.gov/news/Dec1997
/n12301997_9712302.html
Perspective of Size
Water molecules – 3 atoms
Protein molecules – thousands of atoms
DNA molecules – millions of atoms
water molecule
Nanowires, carbon nanotubes – millions of atoms
Carbon
nanotube
Molecule of DNA
Protein molecule
www.iacr.bbsrc.ac.uk/notebook/ courses/guide/dnast.htm
www.phys.psu.edu/~crespi/research/_carbon.1d/public
student.biology.arizona.edu/.../ group2/crystallography.htm
More than just size…
Interesting phenomena:
Chemical – take advantage of large
surface to volume ratio, interfacial
and surface chemistry important,
systems too small for statistical analysis
Electronic – quantum confinement,
bandgap engineering, change in
density of states, electron tunneling
STM of dangling bonds on a
Si:H surface
b
Magnetic – giant magnetoresistance
by nanoscale multilayers, change in
magnetic susceptibility
http://pubweb.acns.nwu.edu/~mhe663/
Electron tunneling
More than just size …
Interesting phenomena:
Mechanical – improved strength
hardness in light-weight
nanocomposites and nanomaterials,
altered bending, compression
properties, nanomechanics of molecular
structures
Optical – absorption and fluorescence of
nanocrystals, single photon phenomena,
photonic bandgap engineering
Fluidic – enhanced flow properties with
nanoparticles, nanoscale adsorbed films
important
Thermal – increased thermoelectric
performance of nanoscale materials,
interfacial thermal resistance important.
Fluorescence of quantum dots
of various sizes
Phonon tunneling
Nanotech – The next new thing?
Old Nanotechnology
New Nanotechnology
Stained-glass windows –
Vastly improved catalysts enhance
surface area to volume ratios
Silver-Halide Photography
Designer drugs
AR-coated lenses
Cheap, sensitive medical
diagnostics
Viruses are nanomachines
Transparent Sunblock
The difference between
old and new nano:
Nanotube-strengthened cables
Now, we are designing and manipulating at the molecular level whereas
before it was either evolution that did it for us or results happened which
we never really understood and so couldn’t optimize.
nanopedia.cwru.edu
NANO AND MECHANICAL PROPERTIES
Hall Petch Effect
τy = τo + kd-1/2
Dr. Chacko Jacob IIT Kharagpur
NANO AND THERMAL PROPERTIES
Reduced melting point of nanocrystals
Tm = Tmbulk (1 – 1/D)
Tm
D
NANO AND THERMAL PROPERTIES
93±3 K for (H2O)48 and
118±3 K for (H2O)118
Hock et al
PRL 103, 073401 (2009)
14 AUGUST 2009
NANO AND ELECTRICAL PROPERTIES
Quantum Wells, Quantum Wires, Quantum Dots
http://www.uspto.gov/web/patents/
classification/uspc257/defs257.htm
http://www.ph.surrey.ac.uk/
http://www.mrsec.wisc.edu/Edetc/background/
quantum_dots/index.html
Dr. Chacko Jacob IIT Kharagpur
NANO AND OPTICAL PROPERTIES
Photonic Bandgap
http://www.monarchwatch.org/update/2006/0131.html
https://www-eng.llnl.gov/emsolve/
emsolve_results_waveguides.html
Dr. Chacko Jacob IIT Kharagpur
http://commons.wikimedia.org/wiki/
File:Opal_Armband_800pix.jpg
Ongoing Research
•Wide bandgap materials
•SiC
•Diamond-like materials
•Gallium Nitride and related materials
•Tungsten oxide, Zinc oxide and other oxide semiconductors
•Carbon Nanotubes/DLC, etc
•Sensors – Gas sensors based on SiC, oxide semiconductors, etc.
•Dilute magnetic semiconductors
•Direct Fluorination of polymers
•Scanning Probe Microscopy techniques for materials characterization
and development
(COMPOUND SEMICONDUCTOR 2002)
Properties of SiC
Wide
bandgap
High thermal
conductivity
High current
High breakdown
densities
field
Low dielectric
constant
High Young’s
modulus
Mechanical
hardness
MEMS
Chemical
stability
High thermal
stability
High wear
resistance
OXIDE SEMICONDUCTORS
Cummins et al.
J. Phys. Chem. B 104, 11449 (2000)
GAS SENSORS
ELECTOCHROMIC DISPLAYS
TRANSPARENT CONTACTS
NANOWIRE LASERS
ANTI FOGGING MIRRORS
http://www.dealsdirect.com.au/p/anti-fog-mirror-radio-highlander/
http://www.figaro.co.jp/en/
Huang et al. Science 292 (5523),1897 (2001)
Carbon Nanotubes
•Sensors – Gas, Biological, etc
•Field Emission (LED, etc) devices
•Conductive plastics
•Conductive adhesives & Connectors
•Molecular electronics
•AFM tips
•Energy storage
•Thermal materials (conduct or insulate)
•Structural composites (Boeing 787,buildings,etc)
•Catalytic & biomedical supports
www.xintek.com
Silicon Carbide
Epitaxial Growth of SiC Films
NEW MOCVD REACTOR
Irregular features
SEM images of some
irregular features (like
hockey stick) in 3C-SiC
films on Si (111)
AFM images of some
hockey stick in 3C-SiC
films on Si (111)
AFM analysis of SiC films grown by
two-step growth process
1st :1100°C for 30 mins.
2nd :1250°C for 2 hrs
10µ
µm
Almost void free
film was grown
on Si (001)
Selective Epitaxial Growth of SiC
• To reduce the interfacial defects and the other
planar defects, selective epitaxial growth (SEG)
on patterned Si substrates followed by epitaxial
lateral overgrowth (ELO) is a promising method
SiO2
a
SiO2
SiO2
Si
b
c
Schematic diagram of SEG followed by ELO process
Selective Epitaxy
of Silicon Carbide
Before Growth
After growth
Faceted
growth
Optical and SEM
images of faceted
growth inside the
windows
300
200
3C-SiC (311)
Intensity
400
3C-SiC (220)
3C-SiC (111)
500
3C-SiC nano-powder
(311)
(220)
(111)
100
0
25
35
45
55
65
75
85
95
2 theta
XRD from
3C-SiC
nanoparticles
d(111)
TEM and
HRTEM
5nm
Silicon Carbide nanowires
10 µm
Dr. Chacko Jacob IIT Kharagpur
SiC core-sheath nanocables
Silicon Carbide Rods
Silicon Carbide Flowers
Self-assembled Silicon
Carbide (Oxide) structures
SEM images of threedimensional flower showing
the symmetrical and ordered
structure of the flowers
Tungsten Oxide
Nanostructures growth by
evaporative techniques
Tungsten Oxide
Shows high catalytic behavior both in
oxidation and reduction reactions.
WO3 is insulator in stoichiometric form
but show conductivity in sub
stoichiometric form
Particularly suitable for NOx gases and
H2S.
Show better selectivity than SnO2 and
ZnO.
Most important electrochromic
material.
36
Growth process
was modified in
such a way that
the hot filament
itself acts as a
source of
Tungsten
Schematic of the modified hot filament chemical vapor
deposition system, inset – Inside the chamber
1 gas source, 2 valve, 3 mass flow controller, 4 MFC set and
display, 5 pressure gauge, 6 gauge display, 7 chamber, 8 pump,
9 tungsten wire, 10 thermocouple, 11 substrate, 12 heater
Optical and FESEM pictures of the as – grown sample surface
The TEM picture on the left shows
few nanoparticles in the
amorphous matrix of WO3-X
300OC
600OC
Magnified by
FESEM
800OC
39
FESEM images of the
nanostructures after
800OC annealing for 20
min.
W18O49 nanorods and
sheets
WO3 Hexagonal platelets
FESEM images of the
sample annealed at 800oC
for 20 min under water
vapor, which produces
mostly WO3 hexagonal
platelets
30 µm
42
Carbon nanotube growth
Iron
5 µm
Self assembled nanoparticles of Fe on Si(100)
Fig. 2 FESEM images of carbon nanotube arrays grown from iron
catalyst at different temperatures (a) 650 °C, (b) 750 °C, (c) 850 °C and
(d) 950 °C.
Fig. 4 HRTEM images of
carbon nanotubes grown
from iron catalyst at
different temperatures (a)
650 °C , (b) 750 °C, (c)
850 °C, (d) 950 °C, (e)
SAED pattern of an
elongated iron
nanoparticle, Lattice
image from a carbon
nanotube grown at (f) 650
°C and (g) 850 °C
Fig 2a FESEM micrograph of the as-grown MWNTs deposited by the APCVD
method using Fe catalyst, (left inset) the EDX spectrum obtained from F-CNT,
(right inset) small bright catalyst particles were detected at the tip of the F-CNT and
the scale bar length is 200nm
Fig 2b FESEM micrograph of the as-grown MWNTs
deposited by the APCVD method using Ni catalyst, (left
inset) the EDX spectrum obtained from N-CNT, (right
inset) small bright catalyst particles were detected at
the tip of the N-CNT and the scale bar length is 200nm
Fig 3a HRTEM
image of the iron
encapsulated CNT
grown by the
APCVD method
using Fe catalyst,
(upper inset)
HRTEM image of
the iron
encapsulated CNTs
grown by the
APCVD method
using Fe catalyst,
(lower inset)
HRTEM image of
interlayer spacing of
graphitic carbon in
F-CNT
Fig 3b HRTEM
image of the
bamboo-like CNT
grown by the
APCVD method
using Ni catalyst,
(upper inset)
HRTEM image of
the bamboo-like
CNTs grown by
the APCVD
method using Ni
catalyst, (lower
inset) HRTEM
image of
interlayer spacing
of graphitic
carbon in N-CNT
Selective growth of CNTs
Selective growth of CNTs
Dr. Chacko Jacob IIT Kharagpur
Dr. Chacko Jacob IIT Kharagpur
Bulb that went bad almost immediately after turning it on
Dr. Chacko Jacob IIT Kharagpur
Note the white stuff on the inside of the glass
Dr. Chacko Jacob IIT Kharagpur
A closer view of the previous
slide
SEM image of the broken filament
Note the white deposits on the filament
Dr. Chacko Jacob IIT Kharagpur
High magnification SEM image
Tungsten oxide nanoparticles 20 -30 nm!!!!!!
Dr. Chacko Jacob IIT Kharagpur
SEM image of the white powder on the glass
Larger tungsten oxide particles but of different morphology
Dr. Chacko Jacob IIT Kharagpur
THE END
Dr. Chacko Jacob IIT Kharagpur