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Resolving the Structure of a Well-Ordered Hydroxyl Overlayer on In2O3(111) : Nanomanipulation and Theory

Wagner, Margareta; Lackner, Peter; Seiler, Steffen; Brunsch, Achim; Bliem, Roland; Gerhold, Stefan; Wang, Zhiming; Osiecki, Jacek LU ; Schulte, Karina LU and Boatner, Lynn A., et al. (2017) In ACS Nano 11(11). p.11531-11541
Abstract

Changes in chemical and physical properties resulting from water adsorption play an important role in the characterization and performance of device-relevant materials. Studies of model oxides with well-characterized surfaces can provide detailed information that is vital for a general understanding of water-oxide interactions. In this work, we study single crystals of indium oxide, the prototypical transparent contact material that is heavily used in a wide range of applications and most prominently in optoelectronic technologies. Water adsorbs dissociatively already at temperatures as low as 100 K, as confirmed by scanning tunneling microscopy (STM), photoelectron spectroscopy, and density functional theory. This dissociation takes... (More)

Changes in chemical and physical properties resulting from water adsorption play an important role in the characterization and performance of device-relevant materials. Studies of model oxides with well-characterized surfaces can provide detailed information that is vital for a general understanding of water-oxide interactions. In this work, we study single crystals of indium oxide, the prototypical transparent contact material that is heavily used in a wide range of applications and most prominently in optoelectronic technologies. Water adsorbs dissociatively already at temperatures as low as 100 K, as confirmed by scanning tunneling microscopy (STM), photoelectron spectroscopy, and density functional theory. This dissociation takes place on lattice sites of the defect-free surface. While the In2O3(111)-(1 × 1) surface offers four types of surface oxygen atoms (12 atoms per unit cell in total), water dissociation happens exclusively at one of them together with a neighboring pair of 5-fold coordinated In atoms. These O-In groups are symmetrically arranged around the 6-fold coordinated In atoms at the surface. At room temperature, the In2O3(111) surface thus saturates at three dissociated water molecules per unit cell, leading to a well-ordered hydroxylated surface with (1 × 1) symmetry, where the three water OWH groups plus the surface OSH groups are imaged together as one bright triangle in STM. Manipulations with the STM tip by means of voltage pulses preferentially remove the H atom of one surface OSH group per triangle. The change in contrast due to strong local band bending provides insights into the internal structure of these bright triangles. The experimental results are further confirmed by quantitative simulations of the STM image corrugation.

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publication status
published
subject
keywords
density functional theory, hydroxylation, indium oxide, scanning tunneling microscopy, water dissociation
in
ACS Nano
volume
11
issue
11
pages
11 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85035751045
  • wos:000416878100100
ISSN
1936-0851
DOI
10.1021/acsnano.7b06387
language
English
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yes
id
266b7ba4-1a1f-4f68-952f-ba3d0848adfa
date added to LUP
2017-12-12 12:58:59
date last changed
2018-01-16 13:27:41
@article{266b7ba4-1a1f-4f68-952f-ba3d0848adfa,
  abstract     = {<p>Changes in chemical and physical properties resulting from water adsorption play an important role in the characterization and performance of device-relevant materials. Studies of model oxides with well-characterized surfaces can provide detailed information that is vital for a general understanding of water-oxide interactions. In this work, we study single crystals of indium oxide, the prototypical transparent contact material that is heavily used in a wide range of applications and most prominently in optoelectronic technologies. Water adsorbs dissociatively already at temperatures as low as 100 K, as confirmed by scanning tunneling microscopy (STM), photoelectron spectroscopy, and density functional theory. This dissociation takes place on lattice sites of the defect-free surface. While the In<sub>2</sub>O<sub>3</sub>(111)-(1 × 1) surface offers four types of surface oxygen atoms (12 atoms per unit cell in total), water dissociation happens exclusively at one of them together with a neighboring pair of 5-fold coordinated In atoms. These O-In groups are symmetrically arranged around the 6-fold coordinated In atoms at the surface. At room temperature, the In<sub>2</sub>O<sub>3</sub>(111) surface thus saturates at three dissociated water molecules per unit cell, leading to a well-ordered hydroxylated surface with (1 × 1) symmetry, where the three water O<sub>W</sub>H groups plus the surface O<sub>S</sub>H groups are imaged together as one bright triangle in STM. Manipulations with the STM tip by means of voltage pulses preferentially remove the H atom of one surface O<sub>S</sub>H group per triangle. The change in contrast due to strong local band bending provides insights into the internal structure of these bright triangles. The experimental results are further confirmed by quantitative simulations of the STM image corrugation.</p>},
  author       = {Wagner, Margareta and Lackner, Peter and Seiler, Steffen and Brunsch, Achim and Bliem, Roland and Gerhold, Stefan and Wang, Zhiming and Osiecki, Jacek and Schulte, Karina and Boatner, Lynn A. and Schmid, Michael and Meyer, Bernd and Diebold, Ulrike},
  issn         = {1936-0851},
  keyword      = {density functional theory,hydroxylation,indium oxide,scanning tunneling microscopy,water dissociation},
  language     = {eng},
  month        = {11},
  number       = {11},
  pages        = {11531--11541},
  publisher    = {The American Chemical Society},
  series       = {ACS Nano},
  title        = {Resolving the Structure of a Well-Ordered Hydroxyl Overlayer on In<sub>2</sub>O<sub>3</sub>(111) : Nanomanipulation and Theory},
  url          = {http://dx.doi.org/10.1021/acsnano.7b06387},
  volume       = {11},
  year         = {2017},
}