nano-sensing, nano-electronics/spintronics, and...
TRANSCRIPT
Kwang S. Kim
Center for Superfunctional Materials
Dept. of Chemistry
Pohang University of Science and Technology
Nano-Sensing,
Nano-Electronics/Spintronics,
and Nano-Optics
Contents
- Functional Molecules/Materials:
Design Strategy toward
* Creation of new paradigms for designing innovative quantum molecular/nanomaterialsystems
* Extending the frontiers of current research in the creation of futuristic electronic/spintronic/optical devices
* Invention of revolutionary technologies for bio-nano-info interfaces
- CAMD Examples: Quantum Theory, DFT, ab initio theory, MD, NEGF
- Nano-recognition: Self-assembly, Self-synthesis
Organic Nanotubes, Metallic Nanostructures (Science)
Ionophores, Receptors, Enzymes; Fullerenes, CNT, Nanotori
Nanomechanical Devices, Photoswitches, DNA Sequencing
- Transport Phenomena: DFT+NEGF
Molecular Electronics / Spintronics : Quantum Computing
Metals, CNT, Graphene: (Nature)
Electrodes: Graphene to replace ITO (Nature Nanotech.)
Super Magneto Resistance (SMR) in GNR: (Nature Nanotech.)
- Nano-optics: nanolens: (Nature)
Near field focusing and magnification beyond diffraction limit thru nanolens
Superfunctional Materials/Devices
Functional nano-materials
Material characterization
Correlation spectroscopy
Chemical/Bio-functional systems
Molecular architectures
•Single electron/photon molecular devices
•Electronics & Mechanics
•Molecular & quantum computing
•Biosensors, biochips, DNA sequencing
•Enzyme Mimetics
•Bioinformatics
Nano-devices
- Self-assembled materials & Self-engineered devices
- Extended supramolecular chemistry
Host-guest interactions: Guests include electron/photon/proton
- Quantum phenomenon driven nano-materials/devices
Computer-aided
molecular design
approach
Research StrategyNanorecognition
Self-assembly,
Self-synthesis
Synthesis of
Building Blocks
Characterization
(structure,
properties)
MotivationSynthesis of Nanomaterials
Unusual electrochemical/photochemical properties
[Quantum properties <= CAMD]
Novel Nanostructures
Design of Nanodevices and NanosensorsSelf-engineered electronics
(Interaction forces: competition vs. cooperation)
Nanomaterials
Nanostructures
Nanodevices
Nanosensors
Design Strategy:
Calculation Methods
Semiempirical, Tight Binding
Density Functional:
Ab initio: MP2, CCSD(T)
Periodic crystal systems:
Atomic and Molecular systems:
PW-DFT
MC
MD
CP-MD, ab initio MD
Excited state ab initio MD
Free energy Perturbation
Simulations:
Theor. Interpretation
Prediction & Design
Quantum Devices – NT
Nonequilibrium
Quantum Electrodynamics
Nanowires, PRL
Nanotubes, JACS
Fullerenes, PRL
Nonlinear optical & Chiral Switches
Nano-electronic/spintronic Devices Nanomechanical Devices Medical Sensors
(Achievements)Functional Molecules,
Materials, Sensors, Devices
hn1 hn2
Moleculae electronics, PRL
Acc. Chem. Res.
+2e-
l1l2
PNAS
JCP
JPCJACS
JACS
Org.Lett.
Angew
Chem PNAS
Molecular Interactions: Chem. Rev.
Science
Chem. Soc. Rev.
Nature
Nature Nanotech
Angew
Chem
PRB
Nature
Dynamical motion of electron charge density
in water for every 10 fs
Electron Carriers
Electron tweezers J. Am. Chem. Soc. 1998
Tuning Molecular Orbitals in Molecular Electronics/Spintronics
Spintronics
Spintronics: Spin + Electronics
utilizing electron spin for electronic devices
Key Features in Spintronics
Spin has long coherence or relaxation time (non-volatile)
Controlling spin requires much less energy than charges.
Spin has the information of phase (quantum coherence).
Spin Valve Devices
Applications
Hard Disk Drive
Giant MagnetoResistance
(Fert & Grünberg)
(Nobel Prize: 2007)
Magnetic Random Access Memory
Tunneling MagnetoResistance
F I F
Tunneling MagnetoResistance
Electron with spin moves through the insulator by tunneling.
Parallel Anti-parallel
F I F
Structure of
Magnetic Junction
Non-magnetic metal
Insulator
Semiconductor
Superconductor
F
Spacer
F
Non-magnetic metal (GMR): HDD Head Insulator (TMR): MRAM
Parallel
smallresistance
AParallel
large
resistance
Magnetoresistance
Difference in resistance between
parallel (P) and anti-parallel (AP)
magnetoresistance ratio:
To become an ideal spin valve,
the MR ratio should be infinte.
AP P P AP
P AP
R R I IMR
R I
The MR ratio for TMR is
larger than that for GMR.
F/Al2O3/F
thickness 1~2 nm
MR 30~70%
Fe/MgO/Fe
MR 220% (CMR)
[Nat. Mater. 3 862 (2004)]
[Nat. Mater. 3 868 (2004)]
CoFeB/MgO/CoFeB
MR 472 % at RT (2006)
MR 804 % at 5K
MR in TMR
GMR: MR 10~20 %
E-field driven Magnetic On/Off Switch
Zero E-Field Non-Magnetic
Non-Zero E-Field Magnetic
6p 10p
Angew Chem Int Ed 46, 7640 (2007)
Density of States
(DOS)
for
3D, 2D, 1D, 0D
Nano Materials
Classical:
L>100nm
Quantum:
L< 10nm
Energy
Energy
Energy
Energy
Den
sit
y o
f S
tate
s
Den
sit
y o
f S
tate
s
Den
sit
y o
f S
tate
s
Den
sit
y o
f S
tate
s
3D 2D
1D 0D
Fe
Co
Ni
Ru
Rh
Pd
Os
Ir
Pt
Magnetism
of
3D, 2D, 1D
Metals
metalicnano-magnets
PW-DFT
scalar-
relativistic
Phys Rev B
69, 193404
(2004)3D 2D 1D
Infinitely long nanowire: intriguing quantum effects: highly unstable
- Only one minimum for
the linear structure of
the CsAu chain.
- Relatively large ratio (~3)
of break force of the CsAu
chain to that of the bulk
CsAu crystal.
Linearization of Au nanowire by Cs-Doping:
Tetramer for pure metal
Tetramer for alloy
Phys. Rev. Lett. 98, 076101 (2007)
0.9 a.u. for CsAu
Electrostatic force
2D 1D
2D
1D
Fractional Quantum Conductance in the Thinning Process
Conductance
4/3 : ~ 4.2 Go
4/1 : ~ 3.5 Go
2/2 : ~2.7 Go
2/1 : ~2.6 Go
Peaks in Exp: 2.4, 4 Go
5/4 x 4 4/3 x 3 2/2 x 3
Electrode effects : fractionally quantized G value
Length dependence for G values : not significant
4/3x35/4x4 4/3x3 2/2x3 5/4x4
Phys. Rev. Lett. 96, 096104 (2006)
1
r r r
L RG E ES H
Basis Set : DZ
Functional : GGA-PBE
Mesh Cutoff : 400 Ry
Geometry Optimization : 0.04 eV/Å
Spin-polarized NEGF Calculations
L S R
2.46 nm
1.7
8nm
†, Im , , Im , ,r r r r
b L b b R b bT E V Tr E V G E V E V G E V
( , ) ( , ) ( , )b b L b R b
eI V T E V f E V f E V dE
h
K-points sampling,
Finite Bias,
Spin Polarized Calculation
Non-collinear Calculation
Parallel Calculation
GGA & LDADFT :
Calculation: Electron and Spin transport: POSTRANS 0.6
†
2
iA E G E G E
p
Electrical currents and Transmission
Electrical currents are determined by transmission probability
Keldysh Nonequilibrium Green’s function method:
Non-interacting electron approximation
( ) ( )r a
L RT E Tr E G E E G E
2
( ) ( ) ( )L R
eI T f f d
h
Landuer-Büttiker formalism
Self-Energy: Renormalization
Level shiftL/R L/R = Re( )
L/R L/R = Im( ) Level broadening
eff L RH H
Chem. Soc. Rev. (2009)
0
0
L L LC
eff
CL CC CR
RC R R
h V
H V H V
V hM M
Screening effect !!
Self-energy
†
†
0 0 0
0 0
0 0
0 0
0 0 0
L L
L L LC
CL CC CR
RC R R
R R
h v
v h V
H V H V
V h v
v h
Set-up of Calculation : Quasi Stationary State
HLL HLL HLLHRRHMM HRRHRRB B
Finite Bias Effect: Hartree Potential
Natural Boundary Condition
2 ( ) 4 ( )eff
scfV r rp ,
,
( ) ( ), 0
( ), 0
( ) ( ),
eff eff
M L bulk
eff eff
M
eff eff
M R bulk
V r V r z
V V r z L
V r V r z L
L RB B
HL HR
HL+Vb/2
HR–Vb/2
( ) ( )effV r r a r b
1( )
2
zr V
L
Contour Integration
Total ~40
contour points
Very efficient !!!
n n nNcontourCG z f z dz G z f z w
EInc_CC 0.5eV
1
2n
B kC
k
G E f E dE G z f z dz ik T G z p
Self-consistent Electron Density
1
L RG ES H
1
ImDM G E f E dEp
( )init r
[ ( )] [ ( )]scf scfH T r V r
( ) ( )i i iH r r
( ) ( )init scfr r
( )final r
NO
YES
,
( ) ( ) ( )scf r D r rn n n
2 ( ) 4 ( )eff
scfV r rp
W. Y. Kim & K. S. Kim, J. Comput. Chem. 29, 1073 (2008).
Non-collinear Spin Calculations
1
Im rG E f E dE p
1
r rr
r r
r r
r
r
G E G EG E
G E G E
GE H
ES
H HH
H H
0
0
SS
S
r r
r
r r
E EE
E E
z
Parallel Calculation:
Most time-consuming steps
Density matrix
1
L RG E ES H
Ncontour
1Im n n nNcontour
DM G z f z wp
, , , , ,R A
L RT E V Tr E V G E V E V G E V
2
( , ) ( ) ( )n L n L R n R nNtrans
eI T E V f E f E w
h
Ntrans
Currents
Parallelization: Almost linear performance
Inversion of Green’s function: ~ O(N3): 99% of the total cpu times
0.0 0.2 0.4 0.60
2
4
6
8
10
cpu
times
(h)
1/ncpus
POSTRANS
SpinKpoints-
samplingBias Parallel
Non-
collinear
Y Y Y Y Y
POSTECH TRANSPORT CODE
J. Comput. Chem.
29, 1073 (2008).
Carbon-based materials for Electronics/Spintronics
Properties…Weak Spin-Orbit Interaction
Spin-orbit (SO) interaction is proportional to Z4.
Organic atoms have weak SO interaction.
Properties…Weak Hyperfine Interaction
For carbon atoms, the most abundant isotopic
form,12C, has no nuclear spin. I = 0
Advantages of Carbon-based materials in Spintronics
Long spin relaxation length
Top-down vs. Bottom-up approaches
Nanomaterials
Top-down
Bottom-up
limitations
1. H-bonding
2. p-p interaction
3. p- H2O interaction
4. Cation-p interaction
H
O
H
H O
H
H
OH
H
O
H
Ag+
Chem. Rev. 100, 4145 (2000)
H
Interactions Forces for Atomic Molecular Assembly(Ionic, Covalent, and Metallic Bondings)
* Noncovalent Bonding for Molelcular Assembly*
~2
~5 kcal/mol
~1 ~2
~30 kcal/mol
~2 ~2
Self Assembly of Calix[4]hydroquinone
Without water
Hexamer OctamerTetramerTrimerDimer
With water
Polymer
8.610.2
47.221.637.439.744.2
11.021.68.8
Binding energy (kcal/mol)
B3LYP/6-31G*
Self-Assembled Arrays of
Calix[4]hydroquinone (CHQ)
Nanotubes
ox.
red.OHO
O
OH
O OH
O
OH
HH
HH
OO
O
O
O O
O
O
top view side view
Science 294, 348 (2001)
J. Am. Chem. Soc. 123, 10747 (2001)
electro/photo-chemical
Nanorecognition
Competition vs.
Cooperation effects
Self-Assembled
NanolensJ. Y. Lee et al. Nature 460, 498 (2009)
Hyper-Refraction:
Beyond Diffraction Limit Near-Field Focusing
and Magnification
H
F
D
R
LSA365
nm UV
1
mm
FDHDRay-tracing
Nano-Micro Tech:
advanced functionalization, minuaturization, high density packing
Top-down approach Bottom-up approach (Fly’s eye)
Thermal reflowFabrications of lenses
Lens grinding/polishing
Self-assembled CHQ nanostructures
Nanolens: CHQ plano-spherical convex lens
-0.5 0.0 0.50.2
0.4
0.6
0.8
D = 1.610 m
H = 0.590 m
R = 0.844 m
Perfect Sphere LENS
Z (
m
)
X (m)
CHQ crystal
1) nucleation 2) 2D growth 3) 3D growth
CHQ lensfractures
film
crystal
film
4) separation
b
1 m 1 m 1 m1 m
d
1 m
c e
l l'
500nm
CHQ film
200 nm 100 nm 100 nm
100 nm
a
2 m
Thermodynamical Analysis :
growth mechanism of
CHQ nanospheres
a
~400nm
250nm30° tilted
Face-up
250nm
~470nmb
30° tilted
Face-down
1m
1m
2m
2m
c~380nm
1m
1m
220nm
Super-resolution of CHQ nanolens (below ½ wavelength)
beyond diffraction limit
Far-fieldOptical Microscope Images
SEM Images
H
F
D
R
LSA
365 nm UV
1 mm
FDHD
Ray-tracing
Finite Difference Time Domain simulations using Maxwell equations
for the optical path of a nanolens
Near–Field Focusing & Magnification
Beyond Diffraction Limit Through a Nanolens
Naturex (µm)
y (
µm
)
x (µm)h=300 nm h=400 nmx (µm)
FDTD simulations - Examples
∆z = -1.5 λ ∆z = -1.0 λ ∆z = -0.5 λ
∆z = 0.5 λ∆z = 0 ∆z = 1.0 λ
• FDTD used to calculate intensity along the POI
at different relative positions of the objective lens (∆z)
• Resolution is estimated from the FWHM of the POI intensity maximum
NA = 0.9
Numerical Scheme
nSIL Resolution – Comparison with SIL
SIL (same objective)
(NA = 1.44)
Max res. SIL
(n = 1.6)
Regions where
nSIL beats SIL
Improvements
Face Down ≈ 25%
Face Up ≈ 35%
Opt. Lett. 35, 2007 (2010)
Applications of Nanolens:
UV lithography using a nanoscale lens
Photochemical imaging through the CHQ lenses.
a, A FDTD simulation image (|Ex|2) of the lens on resist polymer layers.
b, SEM images of developed patterns after irradiating 365nm UV light through the
nanolenses, UV exposure time: 1s for t=0 -500nm, 4s for t>2μm.
c, FDTD simulation images corresponding to b.
d, |Ex|2 corresponding to a, showing sharp peaks at F=500~600 nm.
Magnetic phase transition
M+&C60
Change of spin state
Exohedral
fullerenes
X@C60,
X=N, P, As, O, S
Phys. Rev. Lett.84, 2425 (2000)
C
C C
C C
H H
H
CC
CC
HH
HH
CC
CC
HH
H
CC
C
HH
C
C
CC
CC
C C
HH
C C
CC
H H
CC
CC
HH
CC
CC
HH
CC
CC
HH
CC
CC
HH
C
CC
HH
C
HH
Trannulene
Cyclacene: side view
Cyclacene:
perspective view
Angew. Chem.
Int. Ed.
38, 2256, (1999)
smallest carbon nanotube
Endo/Exo-hedral Fullerenes,
Nanotubes, and Nano-tori
Qubits
Qubits
Ultralong
thinnest
SWNT
d=0.4 nm
PNAS 102, 14155 (2005)
JACS 127, 15336 (2005)
Si
+ + + +- - - - -
Electron transfers
20 nm
Endohedral spins of N@C60; P@C60 for Quantum Computing
(Qubits)
outer tubes
furnace
turbulent flow
laminar flow
inner tube
flow in flow out
substrate
a
b
JACS 127, 15336 (2005)
PNAS 102, 14155 (2005)
ultralong thinnest SWNT
d=0.4 nm
Graphene
Properties…Mechanically
Flexible
Stable at high temperature (3000 oC)
like diamond or CNT
Properties…Electronically
High carrier mobilities over 15,000 cm2V-1S-1
Ballistic transport in submicrometer scale
(0.3 mm) at 300K [Nature Mater. 6, 183 (2007)]
Properties…Magnetically
Long spin relaxation length: 1.5 ~ 2 mm at 300K
due to weak SO and hyperfine interactions [Nature 448, 571 (2007)]
A.K. Geim, K.S. Novoselov, Science 2004/ 2007/2008, Nature 2005.
P. Kim, Nature 2005, Science 2007. K.S. Kim, … B.H. Hong, Nature 2009.
Magnetoresistance
Magnetoresistance (MR) = 114 (%) over the whole Vb range
Vb (Volt)
Synthesis, etching and transferring processes of the large-scale and patterned graphene films. a, Synthesis of patterned graphene films on thin Ni layers. b, Etching by FeCl3 (or acids) and transfer of floating graphene films. c, Etching by HF (or buffered oxide etchant) and transfer of graphene films by a PDMS stamp.
Large-scale Stretchable Graphene
Nature 457, 706-710 (2009).
http://www.nytimes.com/2009/01/20/science/20obbend.html?_r=1OBSERVATORY
With an Ultrathin Film, a Big Step Forward for Flexible Electronics
By HENRY FOUNTAIN
Published: January 19, 2009
Flexible electronics — the kind that might be used in “smart” clothing,
say, or in foldable displays that could make reading news online more
like reading it in print — are still far from an everyday reality. But
scientists in South Korea are reporting a significant advance toward the
development of such devices.
Stretchable graphene electrode patterns transferred onto a silicon-based polymer.
Web Link
Large-scale Pattern Growth of Graphene Films for Stretchable Transparent Electrodes
(Nature)RSS FeedGet Science News From The New York Times »
K. S. Kim, Y. Zhao, H. Jang, S. Y. Lee, J. M. Kim, K. S. Kim,
J.-H. Ahn, P. Kim, J.-Y. Choi, and B. H. Hong,
Large-scale pattern growth of graphene films for
stretchable transparent electrodes,
Nature 457, 706-710 (2009).
Enhancement of micro-Raman intensity
by a CHQ nanolens on graphene
G2D
Relocation of
CHQ nanolenses
for fabrication
FIB-SEM/SIM-images
Dual FIB technique
Nanolens Array
OM image
SEM image
Molecular Electronics with CNT Electrodes
R
L
dEEfEfVETh
eVI RL
,
2 2Non-equilibrium Green’s function method
(Implementation on SIESTA code based on LCAO DFT)
DFT functional: LDA-Perdue-Zunger
SZP basis-setsLandauer-Büttiker formula for I-V characteristics
PE: phenyl ethynyl
PP: pyrrollo pyrrole
Molecular-wire /
CNT-electrodes
C2C1 C3 C4 C5 C6 C7 C8 C9 C10
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10
-0.020
-0.015
-0.010
-0.005
0.000
0.6 V
1.5 V
2.4 V
(C)
0.0 0.6 1.2 1.8 2.4-0.2
-0.1
0.0
e
Vb (V)
e
Atomic indices
Asymmetric Potential Drop at 2.4 V due to the change of molecular chargeScreening of the external bias voltage => change of the charge distribution
High bias voltage : no more screening - change of molecular charge - change of the local potential- asymmetric potential drop
Negative Differential Resistance
Phys. Rev. B 76, 033425 (2007)
0.0 0.6 1.2 1.8 2.4
0
1
2
-400 0 400
-10
-5
0
5
10
Vb(mV)
I(V
) (
nA)
I(V
) (
A
)
Vb(V)
PE
PP
Metals (Au : Ru)
-Hollow site on (111) surface
CNT
-covalent bond to C
Linker
-S or direct contact
Core molecule
-C6 or benzene
Calculation detail
-POSTRANS(SIESTA+NEGF)
-PBE
-150 Ry
-TM pseudopotential
Effect of electrodes
on electronic transport
Au
Ru
CNT/
Graphene
Transmission
0
1
2
Au
Ru
CNT
0
1
2
0
1
2
0
1
2
Tra
nsm
issio
n
(a) with S (b) without S (c) C6 --> benzene
0.0
0.5
1.0
0.0
0.5
1.0
-2 0 20.0
0.5
1.0
-2 0 20.0
0.5
1.0
E-Ef[eV]
-2 0 20.0
0.5
1.0
Extents of broadening and alignment of a peak are of an electrode origin.
Linker dependence
molecule dependence
s-band
p-band
Tra
ns
mis
sio
n
d-band
Au
Ru
CNT
I - V curve
0.0 0.5 1.0 1.5 2.00
10
20
30
Cu
rren
t (
A)
Voltage (V)
0
1
2
3
4
5
CNT-amide
Au
CNT-S
Higher for metals, smaller for CNT
(large coupling limit)
CNT can offer I-V curve non-linearity that is of an electrode origin
Electrodes are not a deterministic factor.
but a useful factor contributing to molecular transport properties.
Conductance
Non-linearity
Caveat
Y. Cho. et al.
J. Phys. Chem. A
113, 4100 (2009).
Creation of the Domain Wall
0 5 10 15 20 25 30 35-8
0
8
16
24
32
40
48
ED
W (m
eV)
WDW
(nm)
B = 0 mT
B = 30 mT
Energy required to create a magnetic domain wall
(EDW)
Spin direction: out of plane
due to the dipole interaction
Edipole > 30 x Eso
WDW = 10 ~ 15 nm
If B ≥ 30 mT, a DW is created.
ㅊ Nature Nanotech. 3, 408 (2008)
SMR: Super Magnetoresistance
The unique band symmetry of GNRs gives
unrivalled MR and highly spin-polarized currents.
Mis-matching in orbital symmetry as well as spin symmetry
leads to the striking enhancement in MR. (super-MR: SMR)
*(giant) GMR: FM-NM-FM, *(collosal) CMR: FM-MgO-FM,
*(tunnel) TMR: FM-Insulator-FM, *(super) SMR: FM-(FM)-FM
Nature Nanotech. 3, 408 (2008)
P
case
AP
case
Parallel Anti-Parallel
Super-MagnetoResistanceAP P
P
R RMR
R
300K:Exponential dependence
Width dependence
8-ZGNR (1.79 nm): ~106 %
32-ZGNR (6.97 nm): ~104 %
5K:
Almost constant
No width dependence
N-ZGNR : ~106-107 %
8-ZGNR
16-
24-
32-
Only α-spin contributes to currents Spin-polarized currents
I-V Characteristics in Zigzag Graphene Nanoribbon
( , ) ( , ) ( , )b b L b R b
eI V T E V f E V f E V dE
h
b
b
dI VG
dV
1R
G
Current, Conductance, and Resistance
RP : The slope shows quantum conductance (Go = 2e2/h = 77.48 S)
due to the perfect transmissions
RAP: Huge resistance due to the zero transmission gap
αβ
αβ
fL-R 5K
300K Vb = 0.09V
Vb=0.15 V
W. Y. Kim & K. S. Kim, Nature Nanotech. 3, 408 (2008)
Spin-valve device based on GNR: Utilization of the edge spin states
Parallel
Anti-Parallel
W. Y. Kim & K. S. Kim, Nature Nanotech. 3, 408 (2008)
AP: AP:
P:P:
SMR GMR/TMRSMR
A novel graphene analogue
Modification:
Defects: Red circles
N doping : Blue circles
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
NN
N
N
Physical properties
Aromaticity is retained
Non-bonding Radicals
A novel graphene analogue
Ultra-Soft Pseudo potential
GGA (PW86) Functionals
7×7 k-point grid
-5
-3
-2
0
2
3
5
K
E-E
F
(eV
) Majority spin
Minority spin
M
Half-metallic band structure Density of states
-2 -1 0 1 2
0
1
2
3
Tra
nsm
issi
on
E-EF (eV)
Majority
Minority
Spin
density
Design & Synthesis of ion receptors & ion sensors
Immense potentials in biological & environmental processesSalts from Sea water; Poisonous materials from water & soils;
Radioactive materials from Nuclear wastes; Drug delivery; Nanotech
FˉClˉ
Chem. Soc. Rev.35, 355 (2006)
Angew. Chem.44, 2899 (2005)
JACS126,8892(2004)
0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.6 -1.8 -2.0
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
Curr
ent density(m
A/c
m2)
Voltage(V)
S
S
H
-O
O-
S
S
O
O
H
Cyclic Voltammogram
1
S S
S S
H H
H
NH2
H
H H
H
NH2O2N
H
O2N
hv 'hv
Sensor
Molecular electronic sensor.
The ON and OFF states would show
different I-V characteristics.
- <bio-nano-devices>
Nanomechanical Device:
Conformation Change by Redox Process
Photo Switch
Molecular Sensing
DNA Sequencing
Molecular Flipper/Robot
New ChemistryNew functional molecules, new chemical systems, molecular clusters, molecular wires, metal wires, 1D/2D molecular systems, hydrogen storage
Novel inophores/receptors (new class of organic molecular systems)
Enzyme mechanisms, Bio-macromolecules, Polymers, Condensed phase
Novel self assembly techniques: self-synthesis
Synthesis of organic nanotubes, nanowires, nanoparticles, nanostructures
Synthesis of ultralong ultrathinest single wall nanotubes
Synthesis of ultra-wide single-layer graphene
Synthesis of nanscale lens with ideal spherical shape through self-assembling
New PhysicsMolecular electronics/spintronics: Super-magnetoresistanceNanoscale lens comparable to wavelength: distinctive optical phenomena :
New nano-optical phenomena: Super-refractionnear-field focusing and magnification (curvilinear beam trajectory)super resolution beyond diffraction limit
Enhancing optical signal for analysis
Improving photolithographic techniques for nanodevices
Optical memory storage, optical nano-sensing, etc
Summary
Acknowledgments:Dr. Woo Youn Kim, Dr. Young Cheol Choi,
Seung Kyu Min, Yeonchoo Cho,
Dr. Daniel R. Mason Dr. Ju Young Lee,
Prof. N. J. Singh Prof. In-Chul Hwang
Prof. Han Myoung Lee and many others …
Prof. Byung Hee Hong (Sungkyunkwan U)
Prof. Philip Kim (Columbia U)