STM Lecture

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The STM experiment

The Royal Swedish Academy of Sciences has decided to award the 1986 Nobel Prizein Physics by one half to

Dr Gerd Binnig and Dr Heinrich Rohrer, IBM Research Laboratory, Zurich,Switzerland, for their design of the scanning tunnelling microscope.

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Electronic Picture

Electrons flow from occupied states into unoccupied states,

one way or the other.

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The Tunneling Current

The geometric and electronicstructures of a surface are convoluted

in STM images. They MUST be

interpreted

( )

2( , , ) ( , )

, Local Density of StatesE Vsample F

F

r

z

tip sampleI V r z f E V r e

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Tip Artifacts

Sharp tip Dull tip

Double Tip

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Ni(110) Pt(111)

Clean surfaces

http://www.almaden.ibm.com/vis/stm/blue.html

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b.a. c.

Ni Growth on Pt(111)

RT

Afterannealing

at 640 K

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110

101

30 x 30 nm image showing

fine network of lines more

clearly

Ni Growth on Pt(111) at RT

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Ni Growth on Pt(111) at 600 K

STM image (100 nm 100

nm) taken at 300 K of Ni

deposited for 40 min. at 640

K. The NiPt AES ratio was

0.65

STM image (100 nm

100 nm) taken at 300 K

of Ni deposited for 60

min. at 640 K. The NiPt

AES ratio was 0.91.

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Reconstructions

Reconstruction of a

PtNi(100) alloy

http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/reconstructions.html

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Surface Composition

PtRh(100)

http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/chemical_resolution.html

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Dislocations and defects

http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/dislocations.html

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Carbon impurities on the surface

http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/segregation.html

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Adsorption

http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/adsorption.html

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Adsorption site determination of C6H6 on Ni (110)

http://www.fhi-berlin.mpg.de/cp/ltsext/adsorptionsite.php

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Surface Reactions3 C2H2 C6H6 on Pd(111)

J. Phys. Chem. B,102 (34), 6521 -6528, 1998

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Electronic Structure matters

TiO2

Ti

Crystal StructureTiO2(110) 11 Surface

Calculated Electronic

Structure

TiOxygen

Contrast Reversal!

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TiO2(110)

Oxygen

Vacancy

Row

Missing Ti

Row

Termination Oxygen

Vacancy

Row

Oxygen

Vacancy

Row

Missing TiMissing Ti

Row

Termination

Row

Termination

Ti

Oxygen

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Gold On TiO2

100 nm 100 nmDeposited at room temperature

100 nm 100 nmFlash-annealed at 500C

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Molybdenum on TiO2

100 nm 100 nm11 minutes of

deposition at room

temperature

100 nm 100 nm11 minutes of deposition at

high temperature

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b.

Anisotropic Mo growth on TiO2

Ti Oxygen

Mo

50 nm 50 nm8 minutes of deposition Annealed at

525C for 1 hour

100 nm 100 nm11 minutes of deposition

Annealed at 513C for 19 hours

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100 nm 100 nmClean TiO2(001)

100 nm 100 nm15 minutes of

deposition at room

temperature

100 nm 100 nm15 minutes of deposition

Annealed for 1 hour at

430C

100 nm 100 nm15 minutes of deposition

Annealed for 15 hours

at 430C

Isotropic Mo Growth

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Characterization of Mo2C

Surface Science 440 (1999) L857L862

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Nano-lithography

Image is 55 nm

70 nm

Go Blue Hens!

Atomic manipulations