P. Grutter

Contacting the Nanoworld

Peter Grutter

Physics Department

McGill University

NSERC, FCAR, CIAR, McGill, IBM, CIHR, GenomeQuebec, CFI, NanoQuebec

P. Grutter

P. Grutter

P. Grutter

Molecular electronics: the issues

• Contacts• Structure-function

relationship between transport process and molecular structure

• Dissipation

• Crosstalk (interconnects)

• Architecture • I-O with a trillion

processors• Fault tolerance• Manufacturing costs

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Does atomic structure of the contact matter?

YES !

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Does atomic structure of the contact matter?

Mehrez, Wlasenko, et al., Phys. Rev. B 65, 195419 (2002)

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Comparison of Experimental and Modeling Results

Mehrez, Wlasenko, et al., Phys. Rev. B 65, 195419 (2002)

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Low-T UHV STM/AFM/FIM

140K,

10-11mbar

quick change between

FIM - AFM/STM mode

Stalder, Ph.D. Thesis 1995

Cross et al. PRL 80, 4685 (1998)

Schirmeisen et al. NJP 2, 29.1

(2000)

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Field Ion Microscopy

(FIM)

E. Muller, 1950’s

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FIM of W(111) tip

Imaging at 5.0 kV

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FIM of W(111) tip

Imaging at 5.0 kV

Manipulating at 6.0 kV

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FIM of W(111) tip

Imaging at 5.0 kV

Manipulating at 6.0 kV

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FIM of W(111) tip

Imaging at 5.0 kV

Manipulating at 6.0 kV

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Single Au atom on W(111) tip

Imaged at 2.1 KV

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W(111) tip on Au(111)

Cross et al.

PRL 80, 4685 (1998)

Schirmeisen et al,

NJP 2, 29.1 (2000)

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Molecular Dynamics Simulations

U. Landman et al, Science 248, 454 (1990)

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W(111) trimer tip on Au(111)

Ead = 21 eV

= 0.2 nm

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Tip relaxation effects

Hofer, Fisher, Wolkow and Grutter Phys. Rev. Lett. 87, 236104 (2001)

W tip on Au(111) surface

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Tip relaxation effects

Hofer, Fisher, Wolkow and Grutter Phys. Rev. Lett. 87, 236104 (2001)

W tip on Au(111) surface

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F(z) and I(z) of W(111) trimer on Au(111)

Schirmeisen et al,

NJP 2, 29.1 (2000)

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Yan Sun,

Sarah Burke

Henrik Mortensn

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Self-assembled quantum dots

50 nm diameter InAs Qdots grown on 10 nm InP and a

InGaAs 2DEG

Sample grown at NRC IMS J. Levebvre, P. Poole, R. Williams et al

J. Crystal Growth (2002)

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First results of cryogenic electrostatic force spectroscopy

R. Stomp,

Y. Miyahara

S. Studenkin (NRC)

A. Sachrajda (NRC)

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distance

tip gap 2DEGQdot

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distance

tip gap 2DEGQdot

Force between capacitor plates

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E

distance

tip gap

InP

InPInP

InAs

InGaAs

2DEGQdot

Force between capacitor plates

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E

distance

tip gap

InP

InPInP

InAs

InGaAs

2DEGQdot

Electrical potential applied between tip

and 2DEG

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E

distance

tip gap

InP

InPInP

InAs

InGaAs

2DEGQdot

Electrical potential applied between tip

and 2DEG

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E

distance

tip gap

InP

InPInP

InAs

InGaAs

2DEGQdot

30-50 nm

Electrical potential lever armcan be tuned by:

applied Vtip-sample

tip-sample separationsample structure

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Contacting a nano-dot with a Au wire

M. Pumarol S. Studenkin (NRC IMS)

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Stimulation of Single Ligand-Gated Ion Channels

Natural Process:Synaptic Transmission

Goal: To study channel gating kinetics and binding forces, while maintaining precise control of agonist location.

Experiment: Ligand-functionalized AFM tip

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N. Cameron, B. Lennox (McGill)

Tethering Scheme:GABA v.s. GABOB

• Is it possible to tether a molecule of GABA without destroying its functionality?

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Tethering Scheme: Polymer Linker

Au -S-(CH2)12-(O-CH2-CH2)23-O-GABOB {alkanethiol} {PEO}

Colloid simulates the AFM tip

Keeps the colloid complex soluble (?)

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Planar Patch-Clamp Chips• Advanced microstructuring techniques are used to produce apertures in planar glass or quartz substrates.• Low noise recordings have been realized from both artificial lipid bilayers and whole cells.

Fertig et. al. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2001 Oct;64(4-1):040901.

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F(z) as a function of

pulling speed

Clausen-Schaumann et al., Current Opinions in Chem. Biol. 4, 524 (2000)

Merkel et al., Nature 397, (1999)

Allows the determination ofenergy barriers and thus is a direct measure of the energy landscape in conformational space.

Evans, Annu. Rev. Biophys. Biomol. Struct., 30, 105 (2001)

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Loading Rate Dependent Unbinding:

Most probable unbinding force:

• Ligand-receptor dissociation forces and rates depend on the rate at which the bond is ruptured!!!• Distinct binding states can be identified from a force v.s. loading rate plot.

Good review: Evans, E. Annu. Rev. Biophys. Biomol. Struct. 2001. 30:105-28.

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Summary

• Tools, both experimental and theoretical, drive our capabilities to understand the nanoworld!

• We develop and apply SPM techniques to interface to:

1. Molecules

2. Quantum dots

3. Neurons

P. Grutter

Supported by

NSERC, FCAR, CIAR, NanoQuebec

CFI, IBM, GenomeQuebec, CIHR

McGill Dawson Scholarship

14 graduate students, 6 post doctoral fellows

P. Grutter