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Structure dependent effect of silicon on the oxidation of Al(111) and Al(100)

Yazdi, Milad G. ; Lousada, Cláudio M. ; Evertsson, Jonas LU ; Rullik, Lisa LU ; Soldemo, Markus ; Bertram, Florian LU ; Korzhavyi, Pavel A. ; Weissenrieder, Jonas LU ; Lundgren, Edvin LU and Göthelid, Mats (2019) In Surface Science 684. p.1-11
Abstract


The effect of sub-monolayer silicon on the oxidation of Al(111) and Al(100) surfaces was investigated using X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculations. On both surfaces the adatom site is preferred over substituting Si into the Al-lattice; on Al(100) the four fold hollow site is vastly favored whereas on Al(111) bridge and hollow sites are almost equal in energy. Upon O
2
exposure, Si is not oxidized but buried at the metal/oxide interface under the growing aluminum oxide. On Al(111), Si has a... (More)


The effect of sub-monolayer silicon on the oxidation of Al(111) and Al(100) surfaces was investigated using X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculations. On both surfaces the adatom site is preferred over substituting Si into the Al-lattice; on Al(100) the four fold hollow site is vastly favored whereas on Al(111) bridge and hollow sites are almost equal in energy. Upon O
2
exposure, Si is not oxidized but buried at the metal/oxide interface under the growing aluminum oxide. On Al(111), Si has a catalytic effect on both the initial oxidation by aiding in creating a higher local oxygen coverage in the early stages of oxidation and, in particular, at higher oxide coverages by facilitating lifting Al from the metal into the oxide. The final oxide, as measured from the Al2p intensity, is 25–30% thicker with Si than without. This observation is valid for both 0.1 monolayer (ML) and 0.3 ML Si coverage. On Al(100), on the other hand, at 0.16 ML Si coverage, the initial oxidation is faster than for the bare surface due to Si island edges being active in the oxide growth. At 0.5 ML Si coverage the oxidation is slower, as the islands coalesce and he amount of edges reduces. Upon oxide formation the effect of Si vanishes as it is overgrown by Al
2
O
3
, and the oxide thickness is only 6% higher than on bare Al(100), for both Si coverages studied. Our findings indicate that, in addition to a vanishing oxygen adsorption energy and Mott potential, a detailed picture of atom exchange and transport at the metal/oxide interface has to be taken into account to explain the limiting oxide thickness.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Aluminum, Density functional theory, Oxidation, Silicon, X-ray photoelectron spectroscopy
in
Surface Science
volume
684
pages
11 pages
publisher
Elsevier
external identifiers
  • scopus:85061563000
ISSN
0039-6028
DOI
10.1016/j.susc.2019.02.005
language
English
LU publication?
yes
id
d808d2d0-5319-44eb-88db-f30fac44855f
date added to LUP
2019-02-25 11:08:06
date last changed
2020-01-13 01:30:35
@article{d808d2d0-5319-44eb-88db-f30fac44855f,
  abstract     = {<p><br>
                                                         The effect of sub-monolayer silicon on the oxidation of Al(111) and Al(100) surfaces was investigated using X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculations. On both surfaces the adatom site is preferred over substituting Si into the Al-lattice; on Al(100) the four fold hollow site is vastly favored whereas on Al(111) bridge and hollow sites are almost equal in energy. Upon O                             <br>
                            <sub>2</sub><br>
                                                          exposure, Si is not oxidized but buried at the metal/oxide interface under the growing aluminum oxide. On Al(111), Si has a catalytic effect on both the initial oxidation by aiding in creating a higher local oxygen coverage in the early stages of oxidation and, in particular, at higher oxide coverages by facilitating lifting Al from the metal into the oxide. The final oxide, as measured from the Al2p intensity, is 25–30% thicker with Si than without. This observation is valid for both 0.1 monolayer (ML) and 0.3 ML Si coverage. On Al(100), on the other hand, at 0.16 ML Si coverage, the initial oxidation is faster than for the bare surface due to Si island edges being active in the oxide growth. At 0.5 ML Si coverage the oxidation is slower, as the islands coalesce and he amount of edges reduces. Upon oxide formation the effect of Si vanishes as it is overgrown by Al                             <br>
                            <sub>2</sub><br>
                                                         O                             <br>
                            <sub>3</sub><br>
                                                         , and the oxide thickness is only 6% higher than on bare Al(100), for both Si coverages studied. Our findings indicate that, in addition to a vanishing oxygen adsorption energy and Mott potential, a detailed picture of atom exchange and transport at the metal/oxide interface has to be taken into account to explain the limiting oxide thickness.                         <br>
                        </p>},
  author       = {Yazdi, Milad G. and Lousada, Cláudio M. and Evertsson, Jonas and Rullik, Lisa and Soldemo, Markus and Bertram, Florian and Korzhavyi, Pavel A. and Weissenrieder, Jonas and Lundgren, Edvin and Göthelid, Mats},
  issn         = {0039-6028},
  language     = {eng},
  pages        = {1--11},
  publisher    = {Elsevier},
  series       = {Surface Science},
  title        = {Structure dependent effect of silicon on the oxidation of Al(111) and Al(100)},
  url          = {http://dx.doi.org/10.1016/j.susc.2019.02.005},
  doi          = {10.1016/j.susc.2019.02.005},
  volume       = {684},
  year         = {2019},
}