Title: The Applications of Nano Materials
1The Applications of Nano Materials
- Department of Chemical and Materials Engineering
- San Jose State University
Zhen Guo, Ph. D.
2How to study Nanomaterials
Part I -- Done
Basic Materials Science Principles
Microstructure
Properties
Materials
Applications
Processing
Part III
Part II This one
3Nano Structure and Device
- Nano structure and device can be accomplished by
two approaches. - -- Bottom Up method where small building blocks
are produced and assembled into larger
structures. - examples chemical synthesis, laser trapping,
self assembly, colloidal aggregation, etc - -- Top Down method where Large object are
modified to give smaller features. - examples film deposition and growth, nano
imprint / lithography, etching technology,
mechanical polishing
4Technology and Characterization of Nano Material
Science Session VI Nano Technology Bottom Up
Approach Session VII Nano Technology Top Down
Approach Session VIII Nano Material
Characterization
5Session VI Nano Materials Synthesis
Nano metallic particle synthesis Nano
semiconductor materials synthesis Carbon based
nano structure synthesis Self assembly nano
materials
Challenge The control of nano particle sizes,
distributions and their locations
6Nano Metallic Magnetic Particles
- Nano metallic particles include single metals
mainly transition metals, alloyed metals and
metal oxide nano particles - The applications of metallic nano particles are
- -- High density magnetic data storage
- -- Dilute magnetic semiconductor (DMS)
- -- Biomedical applications (MRI, NMR, SQUID)
- -- Highly active catalyst (large surface area)
- -- Nucleus for CNT and other nano tube
7Synthesis of Single Metal MNP-- Method I The
Reduction of Metal Salts
- Size control conducting the reaction in a
confined reactor - Nano confined reactor such as water-in-oil or
oil-in-water micro-emulsion system - Size of confined space can be defined by varying
amount of both surfactant and solvent - Successful examples included Fe, Ni and Co
particles
Courtesy from Vincent Rotello, Nanoparticles
8Synthesis of Single Metal MNP-- Method II
Thermal Decomposition
- Thermal Decomposition of organo-metallic
complexes can produce highly mono-disperse nano
particles. - Size and dispersity control is attained through
high reaction temperature - Capping ligands (e.g. Oleic Acid) can also
mediate the particle growth by forming a
monolayer of nano particles - Most common precursors Metal Carbonyl
complexes. - Morphology can also be controlled through
various capping ligands
TOPO Trioctylphosphine Oxide
Courtesy from Vincent Rotello, Nanoparticles
9Alloyed Metal Nano Particles
- Solid-solution alloyed metallic nano particles
can be attained through simultaneous thermal
decomposition - Core-shell alloyed nano particles are produced
by a stepwise reduction process where each
successive step uses larger diameter water
droplet to yield the alloyed core-shell particles
Courtesy from Vincent Rotello, Nanoparticles
10Metal Oxide Nano Particles
- Thermal decomposition of metal organic
precursors on a hot surface. - The size of the nano particles can be controlled
by reaction temperature and / or the ratios of
precursor verse capping ligands
11Nano Silicon Particles
Cubic Si Nano crystals are made by PECVD method
of injecting a dilute mixture (5 SiH4 and 95 of
He) and applying RF power
Thermal Evaporation of Si chips and collected
nano particles in a cold chamberl
12Other Nano Silicon Particles
- Thermal Evaporation
- Sputtering
- Laser ablation
- Electrochemical Etching with catalyst
- Implant (Si, Ge)
- Anneal from Si-rich SiOx (self assembly)
13Semiconductor Compound Nano Particles
- High Temperature Organo-Metallic Methods are
still the most popular for both III-V and II-VI
compound. - Thermal decomposition
- Rapid injection of organometallic precursor means
fast nucleation. - The following growth can be controlled and
terminated by adjusting temperature
14Carbon based nano structures
Bucky ball
Carbon nano tube
http//www.nccr-nano.org/nccr/media/gallery/galler
y_01/gallery_01_03
15Why Ball and Tube Shape?
- In Nano Material Science, high surface and even
edge energy matters. - As we previously discussed, a tiny piece of
graphite would have a lot of atoms at its edge
which is unstable. - Giving opportunities, nano solids would roll
them self up to bucky balls or tubes to minimize
the total energy
http//nanonet.rice.edu/intronanosci/sld005.html
16Making Buckminsterfullerene
- Carbon Arc Experiments
- -- Two Carbon robs arcing in He at 100 Torr.
- -- Can now be reproduced in gram level at a time
- First discovered in 1985, it is most known nano
particles - The round cage like structure of the fullerenes
was reminiscent of the dome structures designed
by the architect Richard Buckminster Fuller, and
so it was named Buckminsterfullerene
17Mechanisms of Carbon Nano tube
- Root Growth Mechanism
- Transition metal as catalyst
- Hydrocarbon dissociate at metal surface into H
and C. - Once surface saturated with C, it starts to form
as graphite sheet with fullerene cap - More C atoms can be inserted into Metal-C bond
so the tube get growing longer.
Courtesy from Rainer Waser Nano-electronics and
Information technology
18Synthesis Methods for CNT
- Electric Arc Discharge similar with the one for
Bucky Ball - Laser Vaporization Graphite target with Co, Ni
powders sitting in 1200C furnace and hit by laser
pulse. CNT collected downstream at cold finger. - CVD pre-patterned structure with Fe, Mo nano
particles in a tube furnace at 1000C and methane
as precursor of carbon - Fullerene recrystallization depositing Ni and
C60 multi-layers and recrystallize at 900C
Courtesy from Rainer Waser Nanoelectronics and
Information technology
19Properties of Carbon Nano Tube
- There are different ways to roll up the graphite
sheet to form carbon nano tube. This
configuration is defined as Chirality - The electronic properties of carbon nano tube are
determined by its chirality. - It can be semiconductor, semimetals or metals
Courtesy from Stanley Wolfe Advanced Silicon
Processing
20Self Assembly of Carbon Nano Tube as interconnect
(Metal)
Courtesy from Stanley Wolfe Advanced Silicon
Processing
21Canbon Nano Tube Semiconductor
Single or Multiple Carbon Nano Tube as FET Channel
Courtesy from Stanley Wolfe Advanced Silicon
Processing
22Self Assembly Nano Technology
- Self assembly can be defined as a coordinated
actions of independent entities under local
control of driving forces to produce a large,
ordered structures or to achieve a desired group
effect. - The driving force of self assembly is usually
based on an interplay of thermodynamics and
kinetics. - -- Chemically Controlled Self-assembly
- -- Physically Controlled Self-assembly
- -- Flip-up Principles and Spacer Techniques
23Chemically Controlled Self Assembly
Deposition of loaded diblock copolymer micelles
- One block is soluble in toluene and the other is
insoluble. - Spherical micelles of copolymer molecular are
formed in toluene - These micelles are loaded with compounds such as
HAuCl4 and deposited on planar substrate. - Oxygen plasma treatment pyrolyses the polymer
and turn precursor into nano Au particles with
short range regular pattern
Courtesy from Rainer Waser Nano-electronics and
Information technology
24Hybrid approach for self assembly
- A template with holes is created using typical
lithography - The deposition process of the micelles is
controlled that only those micelles into grooves
and holes by caterpillar force will remain on the
surface after resist removal. - Copolymer is pyrolysed and a regular Au dot
array obtained
Courtesy from Rainer Waser Nano-electronics and
Information technology
25Why Nano Gold Particles?
The optical applications of nano materials
26Hybrid Approach (II)
- A diblock copolymer solution were spin-coated
and annealed to promote phase separation into
nano scale polymer domains. (Polystyrene and
PMMA) - One phase is removed with an organic solvent,
leaving a porous PS films. - This highly ordered porous film serve as
hardmask to etch into Oxide. - Conformally deposit aSi and etch them using an
anisotropic RIE process. - Annealing to form Si Nano crystal array as
floating gate
Courtesy from K. W. Guarini et al, IEDM 2003
27Physically Controlled Self Assembly
- Film deposition method using Stranski Krastanov
Growth. Followed by initial layer by layer
growth, island-like nano dots are formed to
reduce the elastic strain energy (see next
session) - This technique can also combined with
Lithography. Layer 2 can be conventionally
patterned. Then alternative Layer 1 and 2 deposit
can lead to a perfect SiGe islands at specific
location.
Courtesy from Rainer Waser Nano-electronics and
Information technology
28Flip-up principle and Spacer technique
- Flip-up principle utilized the accurate control
of film thickness at nm scale during deposition
and flip it to vertical dimension - The most known method is spacer technique where
a hard mask is deposited conformally over a
coarse structure. - Then the film were etched anisotropically
leaving only spacer to define nano feature - The next patterning used the spacer as hard mask
and thus turn nano-scale controlled film
thickness into vertical fine structure
Courtesy from Rainer Waser Nano-electronics and
Information technology