stm lecture
TRANSCRIPT
-
8/2/2019 STM Lecture
1/24
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.
http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/stm_schematic.gif -
8/2/2019 STM Lecture
2/24
Electronic Picture
Electrons flow from occupied states into unoccupied states,
one way or the other.
-
8/2/2019 STM Lecture
3/24
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
-
8/2/2019 STM Lecture
4/24
Tip Artifacts
Sharp tip Dull tip
Double Tip
-
8/2/2019 STM Lecture
5/24
Ni(110) Pt(111)
Clean surfaces
http://www.almaden.ibm.com/vis/stm/blue.html
-
8/2/2019 STM Lecture
6/24
b.a. c.
Ni Growth on Pt(111)
RT
Afterannealing
at 640 K
-
8/2/2019 STM Lecture
7/24
110
101
30 x 30 nm image showing
fine network of lines more
clearly
Ni Growth on Pt(111) at RT
-
8/2/2019 STM Lecture
8/24
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.
-
8/2/2019 STM Lecture
9/24
Reconstructions
Reconstruction of a
PtNi(100) alloy
http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/reconstructions.html
-
8/2/2019 STM Lecture
10/24
Surface Composition
PtRh(100)
http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/chemical_resolution.html
-
8/2/2019 STM Lecture
11/24
Dislocations and defects
http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/dislocations.html
-
8/2/2019 STM Lecture
12/24
Carbon impurities on the surface
http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/segregation.html
-
8/2/2019 STM Lecture
13/24
Adsorption
http://eaps3.iap.tuwien.ac.at/www/surface/STM_Gallery/adsorption.html
-
8/2/2019 STM Lecture
14/24
-
8/2/2019 STM Lecture
15/24
Adsorption site determination of C6H6 on Ni (110)
http://www.fhi-berlin.mpg.de/cp/ltsext/adsorptionsite.php
-
8/2/2019 STM Lecture
16/24
Surface Reactions3 C2H2 C6H6 on Pd(111)
J. Phys. Chem. B,102 (34), 6521 -6528, 1998
-
8/2/2019 STM Lecture
17/24
Electronic Structure matters
TiO2
Ti
Crystal StructureTiO2(110) 11 Surface
Calculated Electronic
Structure
TiOxygen
Contrast Reversal!
-
8/2/2019 STM Lecture
18/24
TiO2(110)
Oxygen
Vacancy
Row
Missing Ti
Row
Termination Oxygen
Vacancy
Row
Oxygen
Vacancy
Row
Missing TiMissing Ti
Row
Termination
Row
Termination
Ti
Oxygen
-
8/2/2019 STM Lecture
19/24
Gold On TiO2
100 nm 100 nmDeposited at room temperature
100 nm 100 nmFlash-annealed at 500C
-
8/2/2019 STM Lecture
20/24
Molybdenum on TiO2
100 nm 100 nm11 minutes of
deposition at room
temperature
100 nm 100 nm11 minutes of deposition at
high temperature
-
8/2/2019 STM Lecture
21/24
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
-
8/2/2019 STM Lecture
22/24
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
-
8/2/2019 STM Lecture
23/24
Characterization of Mo2C
Surface Science 440 (1999) L857L862
-
8/2/2019 STM Lecture
24/24
Nano-lithography
Image is 55 nm
70 nm
Go Blue Hens!
Atomic manipulations