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Nanotechnology
J.R.Krenn
Institute for Experimental Physics
Karl-Franzens-University Graz, Austria
[email protected]
nanooptics.uni-graz.at
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 1
Literature
[1] K.E.Drexler, Nanosystems, Wiley, New York, 1992
[2] H.-G.Rubahn, Nanophysik und Nanotechnologie, Teubner, Stuttgart 2002 (german)
[3] R.Waser (ed.), Nanoelectronics and Information Technology, Wiley-VCH, Weinheim, 2003
[3] M.Köhler, Nanotechnologie, Wiley-VCH, Weinheim, 2001 (german)
[4] V.Balzani et al., Molecular Devices and Machines, Wiley-VCH, Weinheim, 2003
[5] I.Fujimasa, Micromachines, Oxford Univ. Press, Oxford, 1996
[6] Nanotech, Special Issue Scientific American, September 2001
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•
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www.nanotechweb.org (news service)
www.nano-tek.org (general)
www.foresight.org/NanoRev/index.html (general)
www.sunsite.nus.edu.sg/MEMEX/nanolink.html (link list)
Illustrations
were taken from websites, books and journals. Great care was taken to assign the respective copyrights.
The names of companies or products mentioned in the following may be the trademark of their respective
owners.
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 2
What is Nanotechnology? (1)
– 1931 M.Knoll, E.Ruska: Electron Microscope
– 1959 Feynman's Talk
'There's plenty of room at the bottom'
www.zyvex.com/nanotech/feynman.html
– 1974 N.Taniguchi: 'Nanotechnology'
– late 80's K.E.Drexler
atom-by-atom 'assembler'
– 90's Molecule-by-Molecule
www.foresight.org
supramolecular chemistry
– late 90's Submicron Scaled Matter
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 3
What is Nanotechnology? (2)
www.foresight.org
Scientific American september 2001
Science november 9, 2001
Problems: (i) energy supply, communication, ...
(ii) scalability, molecular fluctuations, noise, 'sticky' and 'fat' fingers
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 4
What is Nanotechnology? (3)
– The Hardcore Definition
atom or molecular scale assembling
or self organization
– 'Anything goes'
including chemistry, biology,...
novel effects due to
controlled structuring in
the size range 1 to a few 100 nm
Nanoscience
acept.la.asu.edu
– A Pragmatic Definition
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 5
Why Nanotechnology?
To optimize properties readily exploited
increasing speed
mechanics: lower response time, higher resonance frequency
electronics: shorter signal paths, lower parasitic RCL, lower power
dissipation
optics: faster (and higher density) storage, modulation, switching,
routing
material demand (e.g., Ge)
To exploit novel properties
approaching typical wavelength scales, increasing surface / volume ratio
materials: decreasing crystallite size (mechanical strength, magnetic
storage), nanoparticles for catalysis or optics
electronics: quantum effects
optics: near-fields, quantum communication
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 6
Outline (1)
1.
2.
3.
4.
Methods
Electronics
Optics
Mechanics & Materials
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 7
Outline (2)
1.
Methods
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2.
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The Semiconductor Roadmap
Energy Quantization and
Quantum Dots
Conductance Quantization
Molecular Electronics
Scanning Tunneling Microscopy
Optics
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Microscopy and
(Top-Down) Lithography
Nanoimprinting
Bottom-Up Structuring
Electronics
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3.
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4.
Micro-Optics
Near-Field Optics
Scanning Near-Field Optical
Microscopy
Surface Plasmons
Mechanics & Materials
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Micromechanics
Atomic Force Microscopy
Nanophase Materials
Carbon Geometries
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 8
NANOTECHNOLOGY
Part 1. Methods in Nanotechnology
• Microscopy and (Top-Down) Lithography
– Optical
– Electron
– Scanning Probe
• Nanoimprinting
• Bottom – Up Structuring
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 9
Optical Microscopy
Immersion lens
from [2]
© Nikon
transfer function
resolution limit
x  0.61
 2 J ( ) 
I ( )   1 
  
Solid immersion lens (SIL)
2

2

r sin 
0
n sin 
Micro-photoluminescence (a) with and
(b) without SIL (www.uni-karlsruhe.de)
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 10
Confocal Optical Microscopy
© Nikon
High aperture focussing: (a)-(c) plots and
(d)-(f) log. plots of the intensity distribution
in the focal plane of a lens N.A.=0.966.
Intensity ratios of Ix:Iy:Iz=1:0.0081:0.192
M.Mansuripur, Classical Optics, Cambridge Univ. Press, 2002
Marvin Minski 1955
Principle: confocal aperture rejects light not
originating from the focal plane; focussed light
beam & scanning (either light beam or sample)
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 11
Optical Lithography
Light sources: Hg arc lamp (0=436, 365, 248 nm)
KrF laser (0=248 nm), ArF laser (0=193 nm),
F2 laser (0=157 nm)
Lens system: projection reduction typically 1:4
Mask: Cr on glass; production by either focussed
laser beam writing or electron beam lithography;
phase shift masks
Structure transfer to photosensitive polymer resists
dot.che.gatech.edu
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 12
Electron Microscopy
De Broglie wavelength of the electron
E   , p  k  h


1
E k  mv 2  eU , p  mv
2
vac 
n
h
2meU
, med 
Ep
vac
 1
med
eU
h
2m(eU  E p )
U/V
10-1
1
101
102
104
106
v/c
6.3 10-4
2.0 10-3
6.3 10-3
2.0 10-2
0.19
0.94
/nm
3.9
1.2
3.9 10-1
1.2 10-1
1.2 10-2
8.7 10-4
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 13
Transmission Electron Microscopy
www.biologie.uni-hamburg.de
buried hexagonal phase in
cubic CdTe (www.nrel.gov)
electron-sample interaction
Grain boundary in precipitate
aluminum particle (www.lbl.gov)
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 14
Scanning Electron Microscopy
electron-sample interaction
www.jeol.com
Iowa State Univ.
secondary electron detection
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 15
Electron Beam Lithography
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 16
What else a photon or electron can tell
Optical Spectroscopy
The Surface Science Toolbox
Abs., Trans., Refl.
LEED
Low energy electron diffraction
Fluorescence, Raman
AES
Auger electron spectroscopy
EELS
Electron energy loss spectroscopy
Harmonic Generation
UPS
Ultraviolet photoemission spectroscopy
Wave mixing etc.
XPS
X-ray photoemission spectroscopy
XRD
X-ray diffraction
IPES
Inverse photoemission spectroscopy
TDS
Thermal desorption spectroscopy
STM
Scanning tunneling microscopy
STS
Scanning tunneling spectroscopy
Femtosecond time resolution
.....
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 17
Scanning Probe Microscopy (1)
constant gap mode
constant height mode
www.ilp.physik.uni-essen.de
www.fysik.dtu.dk
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 18
Scanning Probe Microscopy (2)
www.omicron.com
Tip: depending on probe type
Scanner: PZT piezoelectrics, electrostrictive
Mechanics: compact design
Electronics: preamplifier, PI feedback loop
www.surfchem.kth.se, www.veeco.com
Computer: scan control, data analysis
Vibration isolation
SPM lithography
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 19
Nanoimprinting
T.Hoffmann, Univ. Wuppertal
Nanoimprinting scheme
(following CD/DVD process)
Example: gold structures on silicon
PMMA resist
S.Chou et al., J.Vac.Sci.Technol.B 14, 4129 (1996)
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 20
Soft Lithography
Replicate Forming, Micro-Contact Printing, (Capillary Moulding)
Univ. of Delaware
Michel et. Al., IBM J. Res. & Dev., Vol. 45, 2001
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 21
Bottom – Up: Molecular Architecture
Epitaxial growth (MBE)
VOx on Pd (111)
7.8 x 7.8 nm2
honeycomb (2 x 2)
(surface-science.uni-graz.at)
Self assembled monolayers
www.ifm.liu.se
AIN on SiC(0001)
(www.asu.edu)
R.D.Piner et al., Science 283, 661 (1999)
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 22
Summary: Lithography
• Top – Down
– optical (semiconductor industry)
– electron (master production, research)
– scanning probe (mainly research)
– Nanoimprinting !
• Bottom – Up supramolecular level
J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 23