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P. Grutter What is Electronics? By electronics we mean the handling of complicated electrical wave forms for communicating information, probing (such as in radar) and data processing. Data processing is the result of one complex stream of information interacting with another. This requires non-linear behavior, otherwise information just gets passed on from one place to the other. (Landauer, Science 1968)
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P. Grutter
Making Contact to Molecules: Interfacing to the Nanoworld
Peter GrutterPhysics DepartmentMcGill University
NSERC, FCAR, CIAR, McGill, IBM, CIHR, GenomeQuebec, CFI, NanoQuebec
P. Grutter
What is Nanoelectronics?
P. Grutter
What is Electronics?• By electronics we mean the handling of complicated
electrical wave forms for communicating information, probing (such as in radar) and data processing.
• Data processing is the result of one complex stream of information interacting with another.
• This requires non-linear behavior, otherwise information just gets passed on from one place to the other. (Landauer, Science 1968)
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
P. Grutter
Does atomic structure of the contact matter?
YES !
P. Grutter
Does atomic structure of the contact matter?
Mehrez, Wlasenko, et al., Phys. Rev. B 65, 195419 (2002)
P. Grutter
Comparison of Experimental and Modeling Results
Mehrez, Wlasenko, et al., Phys. Rev. B 65, 195419 (2002)
P. Grutter
‘Traditional’: infinite, structureless leads -> periodic boundary conditions.
but: - result depends on lead size!- bias not possible due to periodic boundary condition!
Calculating Conductance
Jellium lead Jellium leadmolecule
P. Grutter
Calculation of electrical transport
)],(),([),(2)( 00 eVEfEfVETdEheVI RRLL
O f t e n o n e a s s u m e s t h a t T i s n o t a f u n c t i o n o f V , i . e . :
)(),( ETVET
a n d s t i c k s a l l t h e V d e p e n d e n c e i n t o t h e F e r m if u n c t i o n f
P. Grutter
ab-initio modelling of electronic transport
lead
P. Grutter
DFT plus non-equilibrium Green’s Functions
J. Taylor, H. Guo , J. Wang, PRB 63, R121104 (2001)
1. Calculate long, perfect lead.Apply external potential V by shifting energy levels -> create electrode data base and get potential right
lead
P. Grutter
2. Solve Poisson equation for middle part (device plus a bit of leads); match wavefunctions and potential as a function of V to leads (use data base) in real space.
3. calculated with non-equilibrium Green’s functions (necessary as this is an open system). This automatically takes care of bound states
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
P. Grutter
Reliable, chemically well defined contacts
Cui et al. Nanotechnology 13, 5 (2002), Science 294, 571 (2001)
P. Grutter
P. Grutter
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)
P. Grutter
Field Ion Microscopy
(FIM)
E. Muller, 1950’s
P. Grutter
P. Grutter
FIM of W(111) tip
Imaging at 5.0 kV
P. Grutter
FIM of W(111) tip
Imaging at 5.0 kV Manipulating at 6.0 kV
P. Grutter
FIM of W(111) tip
Imaging at 5.0 kV Manipulating at 6.0 kV
P. Grutter
FIM of W(111) tip
Imaging at 5.0 kV Manipulating at 6.0 kV
P. Grutter
Single Au atom on W(111) tip
Imaged at 2.1 KV
P. Grutter
W(111) tip on Au(111)
Cross et al. PRL 80, 4685 (1998)Schirmeisen et al, NJP 2, 29.1 (2000)
P. Grutter
Molecular Dynamics Simulations
U. Landman et al, Science 248, 454 (1990)
P. Grutter
W(111) trimer tip on Au(111)
Ead = 21 eV
= 0.2 nm
P. Grutter
Tip relaxation effects
Hofer, Fisher, Wolkow and Grutter Phys. Rev. Lett. 87, 236104 (2001)
W tip on Au(111) surface
P. Grutter
Tip relaxation effects
Hofer, Fisher, Wolkow and Grutter Phys. Rev. Lett. 87, 236104 (2001)
W tip on Au(111) surface
P. Grutter
F(z) and I(z) of W(111) trimer on Au(111)
Schirmeisen et al, NJP 2, 29.1 (2000)
P. Grutter
Yan Sun,
Anne-Sophie Lucier
Henrik Mortensen
P. Grutter
The samples (measurements in progress)
A) Au(111) 170 nm×170 nm,B) mixture of C6 and C8 thiol
(ratio 6:1) on Au(111) 450nm×450nm
C) C8 thiol, 6nm×6nm D) C8/C8 dithiol 36nm×36 nm.
P. Grutter
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
P. Grutter
N. Cameron, B. Lennox (McGill)
Tethering Scheme:GABA v.s. GABOB
• Is it possible to tether a molecule of GABA without destroying its functionality?
P. Grutter
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 (?)
P. Grutter
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.
P. Grutter
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.
P. Grutter
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)
P. Grutter
Summary
• Tools, both experimental and theoretical, drive our capabilities to understand the nanoworld!
• We develop and apply SPM techniques to interface to:
molecules and neuronsin order to understand
structure - property relationships
P. Grutter
Supported by NSERC, FCAR, CIAR, NanoQuebecCFI, IBM, GenomeQuebec, CIHR McGill Dawson Scholarship
14 graduate students, 6 post doctoral fellows