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TiOx thin films grown on Pd(100) and Pd(111) by chemical vapor deposition

Farstad, M. H.; Ragazzon, D.; Grönbeck, H.; Strømsheim, M. D.; Stavrakas, C.; Gustafson, Johan LU ; Sandell, A. and Borg, A. (2016) In Surface Science 649. p.80-89
Abstract

The growth of ultrathin TiOx (0≤x≤2) films on Pd(100) and Pd(111) surfaces by chemical vapor deposition (CVD), using Titanium(IV)isopropoxide (TTIP) as precursor, has been investigated by high resolution photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. Three different TiOx phases and one Pd-Ti alloy phase have been identified for both surfaces. The Pd-Ti alloy phase is observed at the initial stages of film growth. Density functional theory (DFT) calculations for Pd(100) and Pd(111) suggest that Ti is alloyed into the second layer of the substrate. Increasing the TTIP dose yields a wetting layer comprising Ti2+ species (TiOx, x ∼0.75). On Pd(100),... (More)

The growth of ultrathin TiOx (0≤x≤2) films on Pd(100) and Pd(111) surfaces by chemical vapor deposition (CVD), using Titanium(IV)isopropoxide (TTIP) as precursor, has been investigated by high resolution photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. Three different TiOx phases and one Pd-Ti alloy phase have been identified for both surfaces. The Pd-Ti alloy phase is observed at the initial stages of film growth. Density functional theory (DFT) calculations for Pd(100) and Pd(111) suggest that Ti is alloyed into the second layer of the substrate. Increasing the TTIP dose yields a wetting layer comprising Ti2+ species (TiOx, x ∼0.75). On Pd(100), this phase exhibits a mixture of structures with (3 × 5) and (4 × 5) periodicity with respect to the Pd(100) substrate, while an incommensurate structure is formed on Pd(111). Most importantly, on both surfaces this phase consists of a zigzag pattern similar to observations on other reactive metal surfaces. Further increase in coverage results in growth of a fully oxidized (TiO2) phase on top of the partially oxidized layer. Preliminary investigations indicate that the fully oxidized phase on both Pd(100) and Pd(111) may be the TiO2(B) phase.

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organization
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type
Contribution to journal
publication status
published
subject
keywords
Density functional calculations, Low energy electron diffraction, Pd, Photoemission spectroscopy, Scanning tunneling microscopy, TiO thin films
in
Surface Science
volume
649
pages
10 pages
publisher
Elsevier
external identifiers
  • Scopus:84959137457
  • WOS:000379097000013
ISSN
0039-6028
DOI
10.1016/j.susc.2016.02.002
language
English
LU publication?
yes
id
82419be0-bf43-4d8a-a818-abde9d3e2237
date added to LUP
2016-04-26 16:18:59
date last changed
2017-02-02 10:25:51
@article{82419be0-bf43-4d8a-a818-abde9d3e2237,
  abstract     = {<p>The growth of ultrathin TiO<sub>x</sub> (0≤x≤2) films on Pd(100) and Pd(111) surfaces by chemical vapor deposition (CVD), using Titanium(IV)isopropoxide (TTIP) as precursor, has been investigated by high resolution photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. Three different TiO<sub>x</sub> phases and one Pd-Ti alloy phase have been identified for both surfaces. The Pd-Ti alloy phase is observed at the initial stages of film growth. Density functional theory (DFT) calculations for Pd(100) and Pd(111) suggest that Ti is alloyed into the second layer of the substrate. Increasing the TTIP dose yields a wetting layer comprising Ti<sup>2+</sup> species (TiO<sub>x</sub>, x ∼0.75). On Pd(100), this phase exhibits a mixture of structures with (3 × 5) and (4 × 5) periodicity with respect to the Pd(100) substrate, while an incommensurate structure is formed on Pd(111). Most importantly, on both surfaces this phase consists of a zigzag pattern similar to observations on other reactive metal surfaces. Further increase in coverage results in growth of a fully oxidized (TiO<sub>2</sub>) phase on top of the partially oxidized layer. Preliminary investigations indicate that the fully oxidized phase on both Pd(100) and Pd(111) may be the TiO<sub>2</sub>(B) phase.</p>},
  author       = {Farstad, M. H. and Ragazzon, D. and Grönbeck, H. and Strømsheim, M. D. and Stavrakas, C. and Gustafson, Johan and Sandell, A. and Borg, A.},
  issn         = {0039-6028},
  keyword      = {Density functional calculations,Low energy electron diffraction,Pd,Photoemission spectroscopy,Scanning tunneling microscopy,TiO thin films},
  language     = {eng},
  month        = {07},
  pages        = {80--89},
  publisher    = {Elsevier},
  series       = {Surface Science},
  title        = {TiO<sub>x</sub> thin films grown on Pd(100) and Pd(111) by chemical vapor deposition},
  url          = {http://dx.doi.org/10.1016/j.susc.2016.02.002},
  volume       = {649},
  year         = {2016},
}