Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniques
We experimentally studied the formation of vacancy clusters and oxygen related defects in uranium oxide (UOx) thin films (<70 nm) changing the stoichiometry in the x = 2.2–3.5 range. Films were deposited on Si(001) by DC magnetron sputtering varying the substrate temperature (room temperature, 40...
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doaj-ae4085366b064d9a82f290494e072f052021-07-17T04:33:34ZengElsevierResults in Physics2211-37972021-08-0127104513Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniquesC. Macchi0A. Somoza1J. Guimpel2S. Suárez3W. Egger4C. Hugenschmidt5S. Mariazzi6R.S. Brusa7CIFICEN (UNCPBA-CICPBA-CONICET) and Instituto de Física de Materiales Tandil (UNCPBA), Pinto 399, B7000GHG Tandil, ArgentinaCIFICEN (UNCPBA-CICPBA-CONICET) and Instituto de Física de Materiales Tandil (UNCPBA), Pinto 399, B7000GHG Tandil, Argentina; Corresponding authors.Comisión Nacional de Energía Atómica - Centro Atómico Bariloche, CONICET and Instituto Balseiro-Universidad Nacional de Cuyo, Avda Bustillo 9500, San Carlos de Bariloche 8400, ArgentinaComisión Nacional de Energía Atómica - Centro Atómico Bariloche, CONICET and Instituto Balseiro-Universidad Nacional de Cuyo, Avda Bustillo 9500, San Carlos de Bariloche 8400, ArgentinaUniversität der Bundeswehr (München) und Institut für Angewandte Physik und Messtechnik, LTR 2 Werner Heinsenberg Weg 39, 85577 Neubiberg, GermanyPhysik-Department E21 and FRMII, Technische Universität München, Lichtenbergstrasse 1, 85748 München, GermanyDepartment of Physics, University of Trento and TIFPA-INFN, via Sommarive 14, I-38123 Povo, Trento, ItalyDepartment of Physics, University of Trento and TIFPA-INFN, via Sommarive 14, I-38123 Povo, Trento, Italy; Corresponding authors.We experimentally studied the formation of vacancy clusters and oxygen related defects in uranium oxide (UOx) thin films (<70 nm) changing the stoichiometry in the x = 2.2–3.5 range. Films were deposited on Si(001) by DC magnetron sputtering varying the substrate temperature (room temperature, 400 °C and 600 °C) and different relative O2 partial pressures in the argon-oxygen mixture. The different species of vacancy-like defects are identified by the combination of depth dependent positron annihilation techniques and by comparison of the experimental data with ab-initio calculations. In samples growth up to 400 °C substrate temperature, di- and tri- vacancies were formed whereas at higher temperature, hexa-vacancies and larger vacancy clusters appear. Film growth at increasing oxygen partial pressure was found not to be correlated with an increase of oxygen defects, but with the formation of more complex vacancy clusters. The presence of oxygen related defects is revealed by identifying preferential positron annihilations with oxygen electrons. Moreover, uranium vacancies inside vacancy clusters are identified by localization of positrons, in agreement with ab-initio calculations.http://www.sciencedirect.com/science/article/pii/S2211379721006239Uranium oxideThin filmsSub-superficial defects distributionPoint defectsPositron annihilation spectroscopy |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
C. Macchi A. Somoza J. Guimpel S. Suárez W. Egger C. Hugenschmidt S. Mariazzi R.S. Brusa |
spellingShingle |
C. Macchi A. Somoza J. Guimpel S. Suárez W. Egger C. Hugenschmidt S. Mariazzi R.S. Brusa Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniques Results in Physics Uranium oxide Thin films Sub-superficial defects distribution Point defects Positron annihilation spectroscopy |
author_facet |
C. Macchi A. Somoza J. Guimpel S. Suárez W. Egger C. Hugenschmidt S. Mariazzi R.S. Brusa |
author_sort |
C. Macchi |
title |
Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniques |
title_short |
Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniques |
title_full |
Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniques |
title_fullStr |
Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniques |
title_full_unstemmed |
Oxygen related defects and vacancy clusters identified in sputtering grown UOx thin films by positron annihilation techniques |
title_sort |
oxygen related defects and vacancy clusters identified in sputtering grown uox thin films by positron annihilation techniques |
publisher |
Elsevier |
series |
Results in Physics |
issn |
2211-3797 |
publishDate |
2021-08-01 |
description |
We experimentally studied the formation of vacancy clusters and oxygen related defects in uranium oxide (UOx) thin films (<70 nm) changing the stoichiometry in the x = 2.2–3.5 range. Films were deposited on Si(001) by DC magnetron sputtering varying the substrate temperature (room temperature, 400 °C and 600 °C) and different relative O2 partial pressures in the argon-oxygen mixture. The different species of vacancy-like defects are identified by the combination of depth dependent positron annihilation techniques and by comparison of the experimental data with ab-initio calculations. In samples growth up to 400 °C substrate temperature, di- and tri- vacancies were formed whereas at higher temperature, hexa-vacancies and larger vacancy clusters appear. Film growth at increasing oxygen partial pressure was found not to be correlated with an increase of oxygen defects, but with the formation of more complex vacancy clusters. The presence of oxygen related defects is revealed by identifying preferential positron annihilations with oxygen electrons. Moreover, uranium vacancies inside vacancy clusters are identified by localization of positrons, in agreement with ab-initio calculations. |
topic |
Uranium oxide Thin films Sub-superficial defects distribution Point defects Positron annihilation spectroscopy |
url |
http://www.sciencedirect.com/science/article/pii/S2211379721006239 |
work_keys_str_mv |
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