J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 1

Nanotechnology

J.R.KrennInstitute for Experimental Physics

Karl-Franzens-University Graz, Austriajoachim.krenn@uni-graz.at

nanooptics.uni-graz.at

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 2

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

• 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 3

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 supramolecular chemistry

– late 90's Submicron Scaled Matter

www.foresight.org

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 4

What is Nanotechnology? (2)

www.foresight.org Science november 9, 2001Scientific American september 2001

Problems: (i) energy supply, communication, ...

(ii) scalability, molecular fluctuations, noise, 'sticky' and 'fat' fingers

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 5

What is Nanotechnology? (3)

– The Hardcore Definitionatom or molecular scale assembling

or self organization

– 'Anything goes'including chemistry, biology,...

– A Pragmatic Definitionnovel effects due to

controlled structuring in

the size range 1 to a few 100 nm

Nanoscience ace

pt.

la.a

su.e

du

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 6

Why Nanotechnology?

To optimize properties readily exploitedincreasing speed

mechanics: lower response time, higher resonance frequencyelectronics: shorter signal paths, lower parasitic RCL, lower power dissipationoptics: faster (and higher density) storage, modulation, switching, routing

material demand (e.g., Ge)

To exploit novel propertiesapproaching typical wavelength scales, increasing surface / volume ratiomaterials: decreasing crystallite size (mechanical strength, magnetic

storage), nanoparticles for catalysis or opticselectronics: quantum effectsoptics: near-fields, quantum communication

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 7

Outline (1)

• Methods

• Electronics

• Optics

• Mechanics & Materials

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 8

Outline (2)

1. Methods• Microscopy and

(Top-Down) Lithography• Nanoimprinting• Bottom-Up Structuring

2. Electronics• The Semiconductor Roadmap• Energy Quantization and

Quantum Dots• Conductance Quantization• Molecular Electronics• Scanning Tunneling Microscopy

3. Optics• Micro-Optics• Near-Field Optics• Scanning Near-Field Optical

Microscopy• Surface Plasmons

4. Mechanics & Materials• Micromechanics• Atomic Force Microscopy• Nanophase Materials• Carbon Geometries

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 9

NANOTECHNOLOGYPart 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 10

Optical Microscopy

θλsin

61.0 0

nx =Δ

© Nikon

2

1 )(2)( √

↵

=

νν

νJ

I

resolution limit

Solid immersion lens (SIL)

transfer function

Micro-photoluminescence (a) with and (b) without SIL (www.uni-karlsruhe.de)

Immersion lens

αλπν sin

2r=

from [2]

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 11

Confocal Optical Microscopy

© Nikon

Marvin Minski 1955

Principle: confocal aperture rejects light not

originating from the focal plane; focussed light

beam & scanning (either light beam or sample)

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.M

ansu

ripur

, Cla

ssic

al O

ptic

s, C

ambr

idge

Uni

v. P

ress

, 200

2

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 12

Optical Lithography

dot.che.gatech.edu

Mask: Cr on glass; production by either focussed laser beam writing or electron beam lithography;phase shift masks

Light sources: Hg arc lamp (λ0=436, 365, 248 nm)

KrF laser (λ0=248 nm), ArF laser (λ0=193 nm),

F2 laser (λ0=157 nm)

Lens system: projection reduction typically 1:4

Structure transfer to photosensitive polymer resists

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 13

Electron Microscopy

)(2,

2 p

medvacEeUm

h

meU

h

−== λλ

mvpeUmvEk ===r

,21 2

λω hkpE === hh ,

eU

En p

med

vac −== 1λλ

U/V v/c λ/nm 10-1 6.3 10-4 3.91 2.0 10-3 1.2101 6.3 10-3 3.9 10-1

102 2.0 10-2 1.2 10-1

104 0.19 1.2 10-2

106 0.94 8.7 10-4

De Broglie wavelength of the electron

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 14

Transmission Electron Microscopy

buried hexagonal phase in cubic CdTe (www.nrel.gov)

www.biologie.uni-hamburg.de

Grain boundary in precipitatealuminum particle (www.lbl.gov)

electron-sample interaction

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 15

Scanning Electron Microscopy

Iowa State Univ. secondary electron detection

www.jeol.com

electron-sample interaction

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 16

Electron Beam Lithography

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 17

What else a photon or electron can tell

LEED Low energy electron diffraction

AES Auger electron spectroscopy

EELS Electron energy loss spectroscopy

UPS Ultraviolet photoemission spectroscopy

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

.....

The Surface Science ToolboxOptical Spectroscopy

Abs., Trans., Refl.

Fluorescence, Raman

Harmonic Generation

Wave mixing etc.

Femtosecond time resolution

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 18

Scanning Probe Microscopy (1)

www.fysik.dtu.dk

constant gap mode constant height mode

www.ilp.physik.uni-essen.de

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 19

Scanning Probe Microscopy (2)

www.surfchem.kth.se, www.veeco.com

www.omicron.com

Tip: depending on probe type

Scanner: PZT piezoelectrics, electrostrictive

Mechanics: compact design

Electronics: preamplifier, PI feedback loop

Computer: scan control, data analysis

Vibration isolation

SPM lithography

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 20

Nanoimprinting

Nanoimprinting scheme

(following CD/DVD process)

T.Hoffmann, Univ. Wuppertal

Example: gold structures on silicon

PMMA resistS.Chou et al., J.Vac.Sci.Technol.B 14, 4129 (1996)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 21

Soft Lithography

Michel et. Al., IBM J. Res. & Dev., Vol. 45, 2001Univ. of Delaware

Replicate Forming, Micro-Contact Printing, (Capillary Moulding)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 22

Bottom – Up: Molecular Architecture

www.ifm.liu.se

Self assembled monolayers

R.D.Piner et al., Science 283, 661 (1999)

Epitaxial growth (MBE)

VOx on Pd (111) 7.8 x 7.8 nm2honeycomb (2 x 2)(surface-science.uni-graz.at)

AIN on SiC(0001)(www.asu.edu)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 1 page 23

• Top – Down– optical (semiconductor industry)– electron (master production, research)– scanning probe (mainly research)

– Nanoimprinting !

• Bottom – Up supramolecular level

Summary: Lithography