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Scanning Tunnelling Microscopy and Spectroscopy of Adsorbates on Aluminium and Silicon

Johansson, Mikael LU (1997)
Abstract
The main topic of this thesis is the investigation of atomic andmolecular adsorbates on single crystal surfaces of silicon and aluminiumusing the techniques of scanning tunnelling microscopy (STM) andspectroscopy (STS). The emphasis has been to use atomic-resolutionspectroscopy and imaging to determine the relationship between thesurfaces' geometric and electronic structures. The STM results have beenprofitably compared with synchrotron-based valence band and core levelphotoelectron spectroscopy (PES) data to provide a more complete picturethan any single technique could provide.



On Si(001) a peak seen in valence band PES at Li coverages up to 0.4 MLwas explained by STM images showing a local perturbation of... (More)
The main topic of this thesis is the investigation of atomic andmolecular adsorbates on single crystal surfaces of silicon and aluminiumusing the techniques of scanning tunnelling microscopy (STM) andspectroscopy (STS). The emphasis has been to use atomic-resolutionspectroscopy and imaging to determine the relationship between thesurfaces' geometric and electronic structures. The STM results have beenprofitably compared with synchrotron-based valence band and core levelphotoelectron spectroscopy (PES) data to provide a more complete picturethan any single technique could provide.



On Si(001) a peak seen in valence band PES at Li coverages up to 0.4 MLwas explained by STM images showing a local perturbation of theSi(001)-2x1 reconstruction by the Li atoms. STM also showed that Liadsorption on p-type substrates created localised electron traps whichinduced negative differential resistance in tunnel spectra.



The formation of 3D islands of metallic MoSi<sub>2</sub> was shown to be a generalfeature of annealing 0.1 - 10 ML Mo films on Si(001) and Si(111) at 800 C.STM and STS showing the growth of the silicide islands at the expense ofatomic-scale features formed at lower temperatures was correlated withPES data showing the changes in the Si bonding on the surface.



STS of Rb on Al(111) revealed that the (Root(3)xRoot(3))R30 overlayer formedat room temperature confined electrons to a 2D quantum well state. STM ofthe growing layer supported existing models for the (Root(3)xRoot(3))R30reconstruction and a complex structure formed at lower coverages, as well asdemonstrating the existence of kinetic barriers to atomic motion on thesurface.



STM of C<sub>60</sub> on Al(111) showed details of the growth of a (2Root(3)x2Root(3))R30ordered overlayer at room temperature. Spectroscopy of an annealedsurface proved that inequivalent molecules in its (6x6) unit cell havedifferent molecular energy levels and bonding to the substrate. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Nogami, Jun, University of Wisconsin-Milwaukee, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Alkali metals, Scanning tunnelling spectroscopies, Scanning tunnelling microscopy, Photoelectron Spectroscopy, Single crystal surface, Silicon, Surface structure, Aluminium, Silicides, Fullerenes., Physics, Fysik, Fysicumarkivet A:1997:Johansson
pages
178 pages
publisher
Div. of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, S-221 00 Lund, Sweden,
defense location
Lecture Hall B, Department of Physics
defense date
1997-10-16 10:15
external identifiers
  • other:ISRN: LUNFD6/NFSF--97/1011--SE
ISBN
91-628-2671-9
language
English
LU publication?
yes
id
6052351b-d6f9-4c36-a8aa-a3e41181ee4a (old id 29528)
date added to LUP
2007-06-13 10:41:32
date last changed
2016-09-19 08:45:09
@phdthesis{6052351b-d6f9-4c36-a8aa-a3e41181ee4a,
  abstract     = {The main topic of this thesis is the investigation of atomic andmolecular adsorbates on single crystal surfaces of silicon and aluminiumusing the techniques of scanning tunnelling microscopy (STM) andspectroscopy (STS). The emphasis has been to use atomic-resolutionspectroscopy and imaging to determine the relationship between thesurfaces' geometric and electronic structures. The STM results have beenprofitably compared with synchrotron-based valence band and core levelphotoelectron spectroscopy (PES) data to provide a more complete picturethan any single technique could provide.<br/><br>
<br/><br>
On Si(001) a peak seen in valence band PES at Li coverages up to 0.4 MLwas explained by STM images showing a local perturbation of theSi(001)-2x1 reconstruction by the Li atoms. STM also showed that Liadsorption on p-type substrates created localised electron traps whichinduced negative differential resistance in tunnel spectra.<br/><br>
<br/><br>
The formation of 3D islands of metallic MoSi&lt;sub&gt;2&lt;/sub&gt; was shown to be a generalfeature of annealing 0.1 - 10 ML Mo films on Si(001) and Si(111) at 800 C.STM and STS showing the growth of the silicide islands at the expense ofatomic-scale features formed at lower temperatures was correlated withPES data showing the changes in the Si bonding on the surface.<br/><br>
<br/><br>
STS of Rb on Al(111) revealed that the (Root(3)xRoot(3))R30 overlayer formedat room temperature confined electrons to a 2D quantum well state. STM ofthe growing layer supported existing models for the (Root(3)xRoot(3))R30reconstruction and a complex structure formed at lower coverages, as well asdemonstrating the existence of kinetic barriers to atomic motion on thesurface.<br/><br>
<br/><br>
STM of C&lt;sub&gt;60&lt;/sub&gt; on Al(111) showed details of the growth of a (2Root(3)x2Root(3))R30ordered overlayer at room temperature. Spectroscopy of an annealedsurface proved that inequivalent molecules in its (6x6) unit cell havedifferent molecular energy levels and bonding to the substrate.},
  author       = {Johansson, Mikael},
  isbn         = {91-628-2671-9},
  keyword      = {Alkali metals,Scanning tunnelling spectroscopies,Scanning tunnelling microscopy,Photoelectron Spectroscopy,Single crystal surface,Silicon,Surface structure,Aluminium,Silicides,Fullerenes.,Physics,Fysik,Fysicumarkivet A:1997:Johansson},
  language     = {eng},
  pages        = {178},
  publisher    = {Div. of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, S-221 00 Lund, Sweden,},
  school       = {Lund University},
  title        = {Scanning Tunnelling Microscopy and Spectroscopy of Adsorbates on Aluminium and Silicon},
  year         = {1997},
}