1953-32 international workshop on the frontiers of modern...
TRANSCRIPT
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1953-32
International Workshop on the Frontiers of Modern Plasma Physics
R. Hatakeyama
14 - 25 July 2008
Tohoku University,Dept. of Electronic EngineeringSendaiJapan
Q-Machine Plasmas Yielding New Experimental Methodologies of Sheared-Flowand Nano-Quantum Physics.
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Q-Machine Plasmas Yielding New Experimental Methodologies of Sheared-Flow and Nano-Quantum
Physics
R. Hatakeyama and T. Kaneko
Department of Electronic Engineering, Tohoku University, Sendai / Japan
International Workshop on The Frontiers of Modern Plasma PhysicsAbdus Salam ICTP, Trieste/Italy, 21-25 July 2008
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The Q machine has been used since the 1960s (~1958) : Ion acoustic, electron plasma, ion cyclotron, drift, … waves and instabilities, nonlinear phenomena such as double layers, …. in magnetized plasmas⇒ Modification to sheared-flow physics study
Innovative transformation of Q machines into the contribution to nano physics & chemistry fields since 1995.
ALKALI METALBEAM OVEN
Work function of solid and ionization potential of atom.
Contact Ionization
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1. Q-Machine Modification Corresponding to Sheared-Flow
Plasma Physics Study
1. Q1. Q--Machine Modification Machine Modification Corresponding to ShearedCorresponding to Sheared--Flow Flow
Plasma Physics Study Plasma Physics Study
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Both the ion and electron emitters are concentrically segmented.
Experimental Setup
Rev. Sci. Instrum. 73 (2002) 4218
(0 V) (0 V)(-60 V)
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Phys. Scripta T107 (2004) 200 Trans. Fusion Sci. Technol. 47 (2005) 128Trans. Fusion Sci. Technol. 51 (2007) 103Plasma Fusion Res. 3 (2008) S1011
Potassium ionflow shear
Cesium ionflow shear
super-position
Effect of hybrid ions
Electron EmitterDetermine space potential
⇒ E×B flow velocityControl of perpendicular
flow velocity shear
Ion EmitterDetermine ion flow energy parallel to BControl of parallel flow velocity shear
super-position
Superposition of K and Cs Ion Flow Velocity ShearsSuperposition of B|| and B⊥ Flow Velocity Shears
-5 0 5r (cm)
φ (V
)
Vee2 = 0 V Vee1(V)
1 V
-2.0-1.0-0.70.01.0
0 20 40VC (V)
No.2
No.1
No.2
r (cm)0
2.5
-2.5
φ Fi||
B|| ShearsB⊥ Shears
Phys. Rev. Lett. 90 (2003) 125001 Phys. Rev. Lett. 92 (2004) 069502Phys. Plasmas 12 (2005) 072103 Phys. Plasmas 12 (2005) 102106
-
-1.92 -1.84 -1.76 -1.68
-1.6
-0.8
0.0
0.8
1.6
2.4(%)
Vee1 (V)V
ie1 (
V)
0
5.0
10.0
15.0
20.0
Vie2= 1.0 V,Vee2= -2.00 VNormalized fluctuation amplitude at r = -1.0 cm (shear region).
A B
B⊥ shear
B//
shea
r No B// shear
No
B⊥
shea
r
turbulent
Superposition of K and Cs Ion Flow Velocity Shears (Drift Wave)
Superposition of B|| and B⊥ Flow Velocity Shears (Drift Wave)
0 4 8
–1.6
–0.8
0.0
0.8
1.6
2.4
Vie1 (V)
ω/2π (kHz)
0 1 2 3 40
1
2
3
Δ Vie (V)
I es/I e
s (%
)0 1 2 3 4
0
1
2
3
I es/I e
s (%
)
Δ Vie (V)
Cs K
Cs+K 0 1 2 3 402
4
6
8
I es/I e
s (%
)
Δ Vie (V)0 1 2 3 4
0
1
2
3
Δ Vie (V)
I es/I e
s (%
)
1 2 3 4 5 6 7 8 9 100
1
2
3
0
0.2
0.4
0.6
Time (a.u.)
n e (×
109
cm
3 )
neTe
T e (e
V)
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Electron Temperature Gradient Instabilitiesin Magnetized Plasmas
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Temperature Gradient Driven Modes in Magnetically Confined Plasmas
• ITG modes are the most plausible candidate for the anomaly of ion channel thermal transport.
• EXB sheared flow suppression effects on ITG modes are identified[1,2].
Ion Temperature Gradient (ITG) Modes Electron Temperature Gradient (ETG) Modes
• ETG modes are also the plausible candidate for the electron transport properties of tokamak devices [3].
• ETG modes are difficult to be stabilized by EXB shear.
INTRODUCTION
[1] Z. Gao, H. Sanuki , K. Itoh, and J.Q. Dong, Phys. Plasmas 10 (2003) 2831.[2] Z. Gao, J. Q. Dong, and H.Sanuki, Phys. Plasmas 11 (2004) 3053. [3] Y.C. Lee, J. Q. Dong, P.N. Guzdar, and C.S. Liu, Phys. Fluids 30 (1987) 1331.
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Why ETG Mode is Important?
• Experimental observation expresses that the low frequency instability is driven by ETG and nonlinear effects of ETG modes generate significant electron transport.
• The growth rate of ETG mode is about 20 times larger than that of short wave length ITG mode.
• It is an important issue to reduce the electron thermal transport observed in magnetically confined fusion devices.
• Therefore it is necessary to examine the role of ETG driven mode in a linear machine so that the result would be applicable in tokamak plasmas.
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ITG mode
ETG mode
Theoretically investigated by Z. Gao, et al., Phys. Plasmas 10 (2003) 2831, 11 (2004) 3053.
Stabilization by ExB shear
ie
ieie nd
Td
,
,, ln
ln=η = electron, ion temperature gradient, and VE‘ is the EXB shear velocity.Where,
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To produce and control electron temperature gradient (ETG) using a thermionic electron superimposed electron cyclotron resonance (ECR) plasma and applying voltages to two different sized mesh grids and finally to examine the stabilization of ETG mode by E X B sheared suppression in a linear machine..
• In laboratory experiments, several techniques have been applied to the control of the electron temperature[4-6], but it is difficult to realize spatially different electron temperatures at a localized area.
[4] G. T. Hoang, et al. Phys. Rev. Lett. 87 (2001) 125001.[5] F. Porcelli, E. Rossi, G. Cima, and A Wootton , Phys. Rev. Lett. 82 (1999) 1458.[6] K. Kato, S. Iizuka, and N. Sato, Appl. Phys. Lett. 65 (1994) 816.
Objective
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EXPERIMENTAL APPARATUS
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Electron emitter (W hot plate)
Grid bias: additional discharge generates low Te electron
Deformation of density and temperature profiles from source to experimental region due to mesh grids
Electron emitter (W hot plate)
Construction of mesh grids
Supply of thermionic low Te electrons from electron emitter (EE)
Thermionic electrons superimposed (SI) ECR plasma50 mm
Grid 2
Grid 1
High Te electrons in ECR plasma
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–5 0 5r (cm)
φ (V
)
VH2 = 0.0 V
VH1 = 1.0 V1 V
0.0 V
–0.65 V
–1.0 V
–2.0 V
By applying different voltages to the electrodes 1, 2, and 3, radial profiles of plasma potentials can be changed and as a resultE X B shear is generated in t h e c e n t r a l r e g i o n
EXB sheared suppression
E X B shear is generated
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Formation and Control of ETG in thermionic electron superimposed ECR plasmas by changing vg2
vg2=-5V vg2= -10V vg2=-50V
vg1= floating potential
No ETG is formed Small ETG is formed ETG becomes large
-5 0 50
2
4
r (cm)
T e (e
V)
-5 0 50
2
4
r (cm)
T e (e
V)
-5 0 50
2
4
r (cm)
T e (e
V)
-5 0 50
4
8
r (cm)
n e (
10
8 cm
-3)
-5 0 50
4
8
r (cm)
n e (
10
8 cm
-3)
-5 0 50
4
8
r (cm)
n e (
10
8 cm
-3)
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2. Innovative Transformation of Q Machine Corresponding to
Nano Physics & Chemistry Study
2. Innovative Transformation 2. Innovative Transformation of Q Machine Corresponding to of Q Machine Corresponding to
NanoNano Physics & Chemistry Study Physics & Chemistry Study
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Electron-based electronics & Information technology
Atom
+-
Exploiting both the two
Semiconductor spintronics
Charge(Semiconductor)
Spin(Magnetic materials)
Electron
● Gaseous atom encapsulated fullerene(H, He, F, N, ・・・)
NLong spin lifetimeSharp resonance
Quantum computer(Atomic nitrogen encapsulated fullerene)
●Endohedral metallofullerene
M+-
Fe
ferromagnetic
Magnetic semiconductor
Endofullerene-based nanoelectronics
Pseudo atom
Charge transfer
Single molecular orientation switchingHigh efficiency solar cellHigh-temperature superconductivity
(Atom encapsulated fullerene)
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Phys. Plasmas 1 (1994) 3480
J. Vac. Sci. Technol. A 14(1996) 615
Generation of Alkali-Fullerene Plasma
Slightly Positive Bias
Positive-Negative Ions Interaction
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Pair C60-Ion and H-ion Plasmas
Phys. Rev. Lett. 91 (2003) 205005 Phys. Rev. Lett., 95 (2005) 175003 Phys. Rev. E, 75 (2007) 056403 Phys. Plasmas, 14 (2007) 055704
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Periodic Table
Alkali-Metals
Halogens
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Alkali-Halogen ( Cs+− I- ) Plasma Generation
Salt: KCl, CsCl, CsI, ….Appl. Phys. Lett. 8888 (2006) 191501
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(10,10)
http://www.photon.t.u-tokyo.ac.jp/index-j.htmlFrom the home page of Maruyama Lab, Univ. Tokyo
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Translation vector Chiral vector
Arm chair tubeArm chair tube
ZigZig--ZagZag tubetube(Narrow gap)
ChiralChiral tubetube(Wide gap)
Metal
Semiconductor
Tube electric properties drastically change from metal to semicoTube electric properties drastically change from metal to semiconductornductor
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SWNT: single-walled nanotube MWNT: multi-walled nanotube
There are 3 basic types of nanotubes
DWNT: double-walled nanotube
Appl. Phys. Lett. 83 (2003) 119 J. Appl. Phys. 96 (2004) 6053
Creation of Evolved Carbon NanotubesCreation of Evolved Carbon NanotubesCreation of Evolved Carbon Nanotubes
Diameter: ~ nmLength: < nm ~ μm ~ mm
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Electron Temperature
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Freestanding growth of individual SWNTs on a flat substrate
From these results(SEM, TEM, Raman)
Freestanding-individual SWNTs have been successfully produced on a silicon-based flat substrate due to plasma-sheath effect !!Chem. Phys. Lett. 381381 (2003) 422; Jap. J. Appl. Phys. (Exp. Lett.) 4343 (2004)
L1278; Nanotechnol. 1717 (2006) 2223 ; Appl. Phys. Lett. 9292 (2008) 031502
On
SiO
2/Si
On
Cu
wire
(e) A
s gr
own
stat
e w
asdi
rect
ly o
bser
ved
by T
EM
Cu wire
Cu wire
・Dgs : 20, 70 mm,・PRF : 40 W,・Tpro : 60, 180 sec,・Tsub: 700, 750℃
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Isolated Bundled
Emission energy [eV]Ex
cita
tion
ener
gy [e
V]
8
2
2
4
8
2
2
4
8
2
2
4
(e)
1.0 1.2 1.4
(d)
1.0 1.2 1.4
(c)
1.0 1.2 1.4
(b)
1.0 1.2 1.4
(a)2.4
1.82.0
2.2
1.0 1.2 1.4
Unique photoluminescence features in freestanding SWNTs
J. Am. Chem. Soc. 130 (2008) 8101
Passage time [h]0 5 10
–1
0
1
I int(6
,5)→
(6,5
) t
I int(6
,5)→
bund
let
0)()( )5,6( =
∂∂
+∂
∂
ttS
ttS bundle
The continuous equation for PL intensity is found to hold in the time trance of isolated and bundled tubes.
Exciton energies transfer from isolated to bundled tubes caused the PL brightening.
Excitation (S22)
–2 0 20
1
Energy [eV]
DO
S (a
.u.)
(8, 7)
(S11)Emission
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3. Inner Nano – Space Control of Carbon Nanotubes Based on
Fundamental Plasma Physics
3. Inner Nano 3. Inner Nano –– Space Control of Space Control of Carbon Nanotubes Based on Carbon Nanotubes Based on
Fundamental Plasma PhysicsFundamental Plasma Physics
“Charge and Spin of Electrons are expected to be effectively exploited”
““Charge and Spin of Electrons are Charge and Spin of Electrons are expected to be effectively exploitedexpected to be effectively exploited””
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Formation of Atom / Molecule Encapsulated Single- and Double-WalledCarbon Nanotubes Using Different-Polarity Ion Plasmas
Formation of Atom / Molecule EncapsulatedFormation of Atom / Molecule Encapsulated SingleSingle-- and Doubleand Double--WalledWalledCarbon Nanotubes Using DifferentCarbon Nanotubes Using Different--Polarity Ion PlasmasPolarity Ion Plasmas
13.6Å 40Å
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SWNTs/DWNTsSWNTs/DWNTs
Plasma Experimental Method
0 V < φap < 50 V
-300 V < φap < 0 V
Junction Formation inside SWNT/DWNT
Stationary Operation
Compound Formation inside SWNT/DWNT
Pulsed Operation
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2 nm 2 nm
SWNTs DWNTs
2 nm
C60@DWNTs
2 nm 2 nm
Cs@DWNTsDWNTsC60@SWNTs
5 nm
I@SWNTs
Cs@SWNTs
Fe(C5H5)2@SWNTs
Fe@SWNTs
1 nm1 nm
DNA@SWNTs
2 nm
TEM Images of Atoms and Molecules Encapsulated SWNTs / DWNTs
5 nm
Ca@SWNTs
Appl. Phys. Lett. 7979 (2001) 4213 Chem. Commun. 11 (2003) 152
Phys. Rev. B 6868 (2003) 075410
Thin Solid Films 464-465 (2004) 299
Appl. Phys. Lett. 89 (2006) 093110
Jpn. J. Appl. Phys. 45 ( 2006) L428Chem. Phys. Lett. 417417 (2006) 288; Jpn. J. Appl. Phys. 45 (2006) 8335
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TEM Images of Pristine and Various Fullerenes Encapsulated SWNTs
Scale bar: 2 nm
C60@SWNT C70@SWNT C84@SWNTPristine SWNT
ellipse
C59N@SWNT
e)
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Electronic Structure inside Atom Encapsulated SWNT
Theoretical calculation!Theoretical calculation!
Bright field STEM imageBright field STEM imageZ-contrast imageZ-contrast image
Encapsulated
Empty
Encapsulated
Empty
Phys. Rev. B 6868(2003) 075410
Cs unfilled Cs filled
STS / STM ResultSTS / STS / STM ResultSTM Result
Collaboration with Y. Kuk’ group Phys. Rev. Lett. 99 (2007) 256407
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4. Electromagnetic Properties of Atom/Molecule Encapsulated
Carbon Nanotubes
4. Electromagnetic Properties of 4. Electromagnetic Properties of Atom/Molecule Encapsulated Atom/Molecule Encapsulated
Carbon NanotubesCarbon Nanotubes
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4.1 Control of Semiconducting Properties of Single-Walled
Carbon Nanotubes
4.1 Control of Semiconducting 4.1 Control of Semiconducting Properties of SingleProperties of Single--Walled Walled
Carbon Carbon NanotubesNanotubes
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A schematic of SWNT-FET
SWNT
An AFM image of SWNT- FET
Field-Effect Transistors (FETs) Based on SWNT
Jpn. J. Appl. Phys. 44 (2005) 1606
Source Drain
IDS VD
VG
Au Au
p- and n-type transport properties appear.
Pristine SWNT
Cn@SWNT
(n = 60, 70, 84)
IDS - VG characteristics(VDS = 1 V, in vacuum, at 297 K)
IDS - VG characteristics(VDS = 1 V, in vacuum, at 297 K)
C59N@SWNT
-40 -20 0 20 400
50
100
150
200
250
VG(V)
I DS(n
A)
Ptistine SWNTC60@SWNTC59N@SWNT
J. Am. Chem. Soc. 130 (2008) 2714.
p n
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Transport Properties of Cs@SWNT(In Vacuum, Room Temp., VDS = 1 V)
45 minD = 6.5×104 /nm2
60 minD = 8.6×104 /nm2
-22.2 V -29.6 V
-35.6 V
15 minD = 2.2×104 /nm2
30 minD = 4.3×104 /nm2
Dependence of Ion Dose on Electrical Characteristics of Cs@SWNTs
p-type
n-type
• As the amount of dosed Cs increases, the threshold for p-type shifts left.
• After 60 min Cs irradiation Cs@SWNT shows completely n-type behavior.
• As the amount of dosed Cs increases, the threshold for p-type shifts left.
• After 60 min Cs irradiation Cs@SWNT shows completely n-type behavior.
Electronic structure of SWNT can be controlled by adjusting an amount of dosed Cs atoms.
Electronic structure of SWNT can be controlled by adjusting an amount of dosed Cs atoms.
Appl. Phys. Lett. 89 (2006) 093121
Cs: Electron donor
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Transport Properties of I @SWNT(In Vacuum,Room Temp.)30 min
Dependence of Ion Dose on Electrical Characteristics of I@SWNT
–40 –20 0 20 400
1
2
I DS
(nA
)
VG (V)
VDS=500 mV
–40 –20 0 20 400
100
200
I DS
(nA
)
VG (V)
VDS=100 mV
–40 –20 0 20 400
20
40
I DS (
nA)
VG (V)
VDS=100 mV
0 500
1
2
3
I DS (
nA)
VG (V)
VDS=100 mV
60 min
120 min 240 min
−20 V −10 V
+10 V +60 V
Enhanced p-type
• As the amount of dosed I increases, the threshold for p-type shifts right.
• After 240 min I irradiation I@SWNT shows a clear enhanced p-type behavior with threshold at 60 V.
• As the amount of dosed I increases, the threshold for p-type shifts right.
• After 240 min I irradiation I@SWNT shows a clear enhanced p-type behavior with threshold at 60 V.
Jpn. J. Appl. Phys., 47 (2008) 2044Jpn. J. Appl. Phys., 47 (2008) 2044
I: Electron acceptor
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4.2 Formation of Nano pn Junctionsby Controlling Different-Polarity
Ion Plasmas
4.2 Formation of Nano 4.2 Formation of Nano pnpn JunctionsJunctionsby Controlling Differentby Controlling Different--Polarity Polarity
Ion PlasmasIon Plasmas
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Controlled Formation of Nano pn Junctions [(Cs/C60)@SWNT]
Pulsed Operation
C60
Cs
5 nm
0 V < φap < 50 V
-300 V < φap < 0 V
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Using Alkali-Halogen ( Cs+- I- ) Plasma
I− Cs+
Nano pn Junction
Halogens
Alkali-Metals
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Nano pn Junction Formed by (Cs/I) @ DWNTICs
-1.0 -0.5 0.0 0.5 1.00
10
20
30
I DS (
nA)
V
DS(V)
For ideal diode measured at V
G= -40 V
IDS = IS (e qVDS / nKBT -1)
IS = 10-12 A; n = 1.5; T= 300 K
A B C D
-40 -20 0 20 400
10
20
30
VG (V)
I DS(
nA)
VDS = 1V
Video link
I-
Cs+
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Nano pn Junction with stable rectifying behavior of (Cs/I)@DWNT and (Cs/I)@SWNT in air
Output characteristics keep stable even in air, indicating p-n junction in SWNTs & DWNTswith high-performance can be fabricated by hetero-atoms or -molecules encapsulation.
-1.0 -0.5 0.0 0.5 1.00
10
20
30
40
50
VG= -40 V
I D
S (nA
)
VDS(V)
In vacuum In air For ideal diode
I Cs
0
1
0 2-2
0
10
VDS [V]
Vacuum
Air
I DS
[nA
]
CsI
(Cs/I)@DWNT (Cs/I)@SWNT
(Baseline upshift for clarity)
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4.3 4.3 4.3 Coulomb Oscillation Characteristics
― Quantum Dot Formation ―
of Encapsulated Carbon Nanotube
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VG
I
The energy level is quantized in a quantum dotThe energy level is quantized in a quantum dot
Current through only when the quantum energy level matches with the fermi energy of drain electrode
Current through only when the quantum energy level matches with the fermi energy of drain electrode
The static energy level in quantum dot can be controlled by externally applied VG
(VDS : constant)
The quantum dot size can be estimated with the Coulomb
oscillation
Investigate the effect of alkali-atom encapsulation on SWNTs
The quantum dot size can be estimated with the Coulomb
oscillation
Investigate the effect of alkali-atom encapsulation on SWNTs
( )dLL
VC
G /2lnπε2e 0
g ≈Δ=
Fig.:Quantum dot and Coulomb oscillation formed by a single dot
L: Dot sized: SWNT diameter
ΔVG
Coulomb oscillation
Tunneling barrier Tunneling barrier
Quantum dot
CarrierSource electrode potential
Drain electrode potential
Potential in a quantum dot
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Coulomb Oscillations Observed in Encapsulated Nanotubes
-15 -10 -5 0 5 10 15
0.0
0.3
0.6
0.9
1.2
I DS (n
A)
VG(V) -40 -20 0 20 40 60
0.0
0.2
0.4
0.6
0.8
I DS (n
A)
VG(V)
Cs@SWNT C60@SWNT
Fe@SWNT Cs@DWNT
Quantum dots formed in nanotubes due to foreign materials encapsulation.
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SummaryHistorical evolutions over 50 years of Q-machine plasma
researches are reviewed, where a special emphasis is placed on experimental methodologies of sheared-flow and nano-quantum physics.
Following the drift-wave studies on superposition effects of parallel and perpendicular flow velocity shears and hybrid ions flow velocity shears, an experiment on electron temperature gradient (ETG) instabilities is started, where the large ETG is successfully generated with the radial density profile kept uniform using thermionic electron superimposed ECR plasma.
The innovative transformation of Q machine plasmas for nano physics and chemistry studies has been performed in order to create novel nano-structures and new functional nano-materials by controlling inner nano-spaces of fullerenes and carbon nanotubes.
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Welcome to
Fukuoka, J
apan
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R. Hatakeyama (Chairman)Department of Electronic Engineering, Tohoku University6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, JapanTelephone: +81-22-795-7045Facsimile: +81-22-263-9375E-mail: [email protected]
International Interdisciplinary-Symposium on Gaseous and Liquid Plasmas
(ISGLP2008)September 5-6, 2008
Tohoku University / Sendai, Japan
http://www.plasma.ecei.tohoku.ac.jp/ISGLP/August 2008Final announcement/program
August 2008Four-page papers deadline for a proceedings volume
June 2008Second announcement
May 2008One-page abstract deadline
March 2008First announcement and call for papersCalendar of Events
Satellite Meeting of International Congress on Plasma Physics (ICPP2008)