Thermally Activated Processes at the Co/ZnO Interface Elucidated Using High Energy X-rays

Jacques A. Dumont; Mac C. Mugumaoderha; Jacques Ghijsen; Sebastian Thiess; Wolfgang Drube; Bente Walz; Martin Tolkiehn; Dmitri Novikov; Frank M. F. de Groot; Robert Sporken

doi:10.1021/jp108744c

Thermally Activated Processes at the Co/ZnO Interface Elucidated Using High Energy X-rays

Jacques A. Dumont^*, Mac C. Mugumaoderha, Jacques Ghijsen, Sebastian Thiess, Wolfgang Drube, Bente Walz, Martin Tolkiehn, Dmitri Novikov, Frank M. F. de Groot, Robert Sporken

^*Corresponding author for this work

Sub Inorganic Chemistry and Catalysis

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

A detailed picture of the thermally activated proces occurring at the Co/ZnO interface is obtained by a combination of high energy X-ray based techniques: X-ray photoelectron and absorption spectroscopies and the kinematical X-ray standing wave method. At room temperature, the growth of a few monolayers of cobalt proceeds by the nucleation of nanometer-sized clusters on the polar oxygen-terminated (000 (1) over bar surface of a ZnO single crystal. Progressive annealing from 600 to 970 K allows separating the Various interfacial reactions. At the lowest annealing temperature, Co clusters Coalesce while keeping their metallic character. Above 700 K Co-0 is gradually oxidized to Co2+ and a tain Co rich (Zn, Co)O layer is annealing temperature (970 K), Co diffuses deeper into ZnO and Zn vacancies are created at subsurance sites that were previously Occupies by Co.

Original language	English
Pages (from-to)	7411-7418
Number of pages	8
Journal	Journal of Physical Chemistry C
Volume	115
Issue number	15
DOIs	https://doi.org/10.1021/jp108744c
Publication status	Published - 21 Apr 2011

Funding

We thank W. Caliebe for providing a CoO crystal. This work was supported by the Belgian Fund for Scientific Research (FNRS-FSR), by the Belgian Office for Scientific, Technical and Cultural Affairs (PM 5.01) and by DESY and the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 226716. J.A.D. and J.G. are respectively postdoctoral researcher and research associate from the Belgian National Fund for scientific Research (NFSR).

Keywords

ZNO
METAL
SPECTRA
SURFACE
OXIDE
PHOTOEMISSION
SPECTROSCOPY
SOLUBILITY
FILMS

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title = "Thermally Activated Processes at the Co/ZnO Interface Elucidated Using High Energy X-rays",

abstract = "A detailed picture of the thermally activated proces occurring at the Co/ZnO interface is obtained by a combination of high energy X-ray based techniques: X-ray photoelectron and absorption spectroscopies and the kinematical X-ray standing wave method. At room temperature, the growth of a few monolayers of cobalt proceeds by the nucleation of nanometer-sized clusters on the polar oxygen-terminated (000 (1) over bar surface of a ZnO single crystal. Progressive annealing from 600 to 970 K allows separating the Various interfacial reactions. At the lowest annealing temperature, Co clusters Coalesce while keeping their metallic character. Above 700 K Co-0 is gradually oxidized to Co2+ and a tain Co rich (Zn, Co)O layer is annealing temperature (970 K), Co diffuses deeper into ZnO and Zn vacancies are created at subsurance sites that were previously Occupies by Co.",

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author = "Dumont, {Jacques A.} and Mugumaoderha, {Mac C.} and Jacques Ghijsen and Sebastian Thiess and Wolfgang Drube and Bente Walz and Martin Tolkiehn and Dmitri Novikov and {de Groot}, {Frank M. F.} and Robert Sporken",

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doi = "10.1021/jp108744c",

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T1 - Thermally Activated Processes at the Co/ZnO Interface Elucidated Using High Energy X-rays

AU - Dumont, Jacques A.

AU - Mugumaoderha, Mac C.

AU - Ghijsen, Jacques

AU - Thiess, Sebastian

AU - Drube, Wolfgang

AU - Walz, Bente

AU - Tolkiehn, Martin

AU - Novikov, Dmitri

AU - de Groot, Frank M. F.

AU - Sporken, Robert

PY - 2011/4/21

Y1 - 2011/4/21

N2 - A detailed picture of the thermally activated proces occurring at the Co/ZnO interface is obtained by a combination of high energy X-ray based techniques: X-ray photoelectron and absorption spectroscopies and the kinematical X-ray standing wave method. At room temperature, the growth of a few monolayers of cobalt proceeds by the nucleation of nanometer-sized clusters on the polar oxygen-terminated (000 (1) over bar surface of a ZnO single crystal. Progressive annealing from 600 to 970 K allows separating the Various interfacial reactions. At the lowest annealing temperature, Co clusters Coalesce while keeping their metallic character. Above 700 K Co-0 is gradually oxidized to Co2+ and a tain Co rich (Zn, Co)O layer is annealing temperature (970 K), Co diffuses deeper into ZnO and Zn vacancies are created at subsurance sites that were previously Occupies by Co.

AB - A detailed picture of the thermally activated proces occurring at the Co/ZnO interface is obtained by a combination of high energy X-ray based techniques: X-ray photoelectron and absorption spectroscopies and the kinematical X-ray standing wave method. At room temperature, the growth of a few monolayers of cobalt proceeds by the nucleation of nanometer-sized clusters on the polar oxygen-terminated (000 (1) over bar surface of a ZnO single crystal. Progressive annealing from 600 to 970 K allows separating the Various interfacial reactions. At the lowest annealing temperature, Co clusters Coalesce while keeping their metallic character. Above 700 K Co-0 is gradually oxidized to Co2+ and a tain Co rich (Zn, Co)O layer is annealing temperature (970 K), Co diffuses deeper into ZnO and Zn vacancies are created at subsurance sites that were previously Occupies by Co.

KW - ZNO

KW - METAL

KW - SPECTRA

KW - SURFACE

KW - OXIDE

KW - PHOTOEMISSION

KW - SPECTROSCOPY

KW - SOLUBILITY

KW - FILMS

U2 - 10.1021/jp108744c

DO - 10.1021/jp108744c

M3 - Article

SN - 1932-7447

VL - 115

SP - 7411

EP - 7418

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

IS - 15

ER -

Thermally Activated Processes at the Co/ZnO Interface Elucidated Using High Energy X-rays

Abstract

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Keywords

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