J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 1 NANOTECHNOLOGY Part 2. Electronics The...
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Transcript of J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 1 NANOTECHNOLOGY Part 2. Electronics The...
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 1
NANOTECHNOLOGYPart 2. Electronics
• The Semiconductor Roadmap
• Energy Quantization and Quantum Dots
• Conductance Quantization
• Molecular Electronics
• Scanning Tunneling Microscopy
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 2
The Semiconductor Roadmap
www.iso.gmu.edu
The SIA (Semiconductor Industry Association) roadmap projects a continuing miniaturization of silicon semiconductor devices for the next 15
years. International Technology Roadmap for Semiconductors (ITRS):
public.itrs.net
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 3
Moore's Law
www.physics.udel.edu
Gordon Moore, co-founder of Intel, 1965
dot.che.gatech.edu
Hg arc lamp 0=436, 365, 248 nm, KrF laser 0=248 nm, ArF laser 0=193 nm, F2 laser 0=157 nm
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 4
Future Lithography Systems
Synchrotron radiation based lithography Lawrence Berkeley National Laboratory (2002)
Prcatically all materials absorb strongly between =157 and 14 nm
Extreme UV laser based plasma sources =10-14 nm, mirrors, reflection masks
X-ray X-ray tube, synchrotron ~1 nm, Fresnel lenses
Ion projection, (Focused Ion Beam)
EUV lithography unit
oemagazine.com
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 5
Electronic Elements: Challenges
• scaling rules
• gate dielectric silicon-dioxide ~ 1.5 nm=> high-k materials as Al2O3, TiO2,...
• dopant fluctuations, noise
• thermodynamics
• quantum effects: discretization and tunneling
• logic circuit architecturewww-hpc.jpl.nasa.gov
www.unine.ch
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 6
Possible Future Directions
Advanced MOSFET concepts
3D architecture
Superconducting electronics
Single electron devices
Spintronics
Quantum computing: qubits
DNA computing
from [3]
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 7
Energy Quantization
from [2]
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 8
Quantum Dots (1)
quantum dot size = the energy determining parameter
)(
225.11
22 0 eVEmEmm
h
mE
h
mm
e ===
Bawendi Group, MIT
II-VI as CdSe, III-V as GaAs, Si, Ge,...
22
222 1,
22ee
Em
h
m
kE
∝Δ==
h
Al e=0.36 nm
GaAs e=21.2 nm
2D GaAs e=47.3 nm
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 9
Quantum Dots (2)
Coloumb blockade
Single electron devices, single electron transistor (SET)
'Artificial atoms' with tuneable electronic properties
(simulate atom shell structure, quantum decoherence, break radial
symmetry => quantum chaos, combine QD's to make artifical bulk
materials,... )
Canditates for quantum computing
2
2
2,
e
hRTk
C
eW tunnelBC >>>>=
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 10
Quantum Dots (3)
Sketch of vertical QD
L.Kouwenhoven, C.Marcus, Physics World June 1998, p.35
(a) Current flow through a quantum dot structure, (b) analogon in terms of 2D circular orbits, (c) periodic table for artifical 2D atoms
Eadd=e2/C+ΔE
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 11
Quantum Dots (4)
www.nanoscience.unibas.ch
Lateral QD on AlxGa1-xAs / GaAs
L.Kouwenhoven, C.Marcus, Physics World June 1998, p.35
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 12
Conductance Quantization 1
Vh
eJ
eVh
edE
h
edJ
EvELDOS
dEELDOSdn
EvdnedJ
V
V
D
D
2
1
1
2
)(22
)(
1)(
)(
)(
2
1
=
−−=−=
=
=↔↔−=
hπ
Ω= ke
h9.12
2 2Unil. Leiden, NL
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 13
Conductance Quantization 2
meso.deas.harvard.edu/spm.html
Thermal conductance quantization
M.Worloch et al., Appl.Phys.Lett. 70, 2687 (1997)
h
TkG Btherm 3
22π=
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 14
Molecular Electronics (1)
Towards the ultimate (?) miniaturization by using single organic molecules as electronic switches and storage elements
electronic properties can be adjusted via the chemical structure
size, speed, power consumption, cost
individuals absolutely identical
Hybrid molecular electronics
Mono-molecular electronics
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 15
Molecular Electronics (2)
Electrodes: covalent vs. van der Waalsstability vs. self-organization
Wires: delocalized π-systems, e.g., polyene
Diodes: molecules with donor-acceptor substructure
www.ifm.liu.se
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 16
Molecular Electronics (3)
from [6]
Switches and storage elements: metalstable molecules
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 17
Scanning Tunneling Microscopy (STM) 1
stm1.phys.cmu.edu
Example:Si(111)7x76x6 nm2
SEM imageof W tip
www.nottingham.ac.uk/
nprl.bham.ac.uk
)exp( sAs
VJ φρ −=
ρLDOSwork function
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 18
STM (2)
from [3]
STM on InP Quantum corrals
M.F.Crommie et al., Science 262, 218 (1993)
M.F. Crommie, Surf. Rev. Lett. 2, 127 (1995)
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 19
Scanning Tunneling Spectroscopy
Vd
JdV
V
J
dV
dJ
ds
Jd
JJAs
J
ds
dJ
ln
ln)(
ln2
∪?=
√↵
∪?
∪−−=
ρ
φ
φφ
)exp( sAs
VJ φρ −=
cond
-mat
.phy
s.hu
ji.ac
.il
5 nm InAs nanoparticles
J.R.Krenn – Nanotechnology – CERN 2003 – Part 2 page 20
Conclusion
Conventional electronics meets its limits within 15 yrs
Novel electronic device types are to be expected
Molecular electronics has yet to prove its feasibility