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ZrB2 thin films deposited on GaN(0001) by magnetron sputtering from a ZrB2 target
Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
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2016 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 453, 71-76 p.Article in journal (Refereed) PublishedText
Abstract [en]

ZrB2 films were deposited on 900 °C-preheated or non-preheated GaN(0001) surfaces by direct current magnetron sputtering from a compound target. Analytical transmission electron microscopy and scanning transmission electron microscopy with energy dispersive X-ray spectroscopy and electron energy loss spectroscopy revealed a 0001 fiber textured ZrB2 film growth following the formation of a ~2 nm thick amorphous BN layer onto the GaN(0001) at a substrate temperature of 900 °C. The amorphous BN layer remains when the substrate temperature is lowered to 500 °C or when the preheating step is removed from the process and results in the growth of polycrystalline ZrB2 films. The ZrB2 growth phenomena on GaN(0001) is compared to on 4H-SiC(0001), Si(111), and Al2O3(0001) substrates, which yield epitaxial film growth. The decomposition of the GaN surface during vacuum processing during BN interfacial layer formation is found to impede epitaxial growth of ZrB2.

Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 453, 71-76 p.
Keyword [en]
A1. X-ray diffraction; A1. Interfaces; A1. Energy-dispersive X-ray spectroscopy; A1. Electron energy loss spectroscopy; A3. Physical vapor deposition processes; B1. Borides
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:liu:diva-130920DOI: 10.1016/j.jcrysgro.2016.08.011OAI: oai:DiVA.org:liu-130920DiVA: diva2:956682
Available from: 2016-08-31 Created: 2016-08-31 Last updated: 2016-08-31Bibliographically approved
In thesis
1. ZrB2 Thin Films: Growth and Characterization
Open this publication in new window or tab >>ZrB2 Thin Films: Growth and Characterization
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Zirconium diboride, ZrB2, is a ceramic material with bulk properties such as high melting point (3245 °C), high hardness (23 GPa), and low resistivity (~8 μΩcm). Thin film growth of ZrB2 using physical vapor deposition has suffered from problems with films deviating from stoichiometry and with high levels of contaminants, especially high oxygen content. The homogeneity range of ZrB2 is very narrow, and consequently it is vital to achieve the correct stoichiometry to grow films with high crystalline order.

This thesis describes a direct current magnetron sputtering process to grow stoichiometric ZrB2 thin films with a low degree of impurities. Growth of epitaxial ZrB2 films was achieved on 4H-SiC(0001), Si(111) and Al2O3(0001) substrates. The effect of deposition temperature and power applied on the sputtering target was investigated and showed that high power density (8.77 Wcm-2) and high temperature (900 °C) resulted in films with the best composition and the highest crystal quality. ZrB2 films on GaN(0001) templates exhibit an amorphous layer at the film-substrate interface and the resulting films are either polycrystalline or textured.

Resistivity measurements showed that the ZrB2 thin films exhibit typical resistivity values of ~100-250 μΩcm and that the resistivity decreased with increasing deposition temperature.

Nanoindentation was applied to assess the mechanical properties of the films. The epitaxial ZrB2 films exhibit high elastic recovery and a hardness of ~45-50 GPa, twice as high as the literature bulk value. In addition, evaluation of the mechanical properties was performed at high temperatures of up to 600 °C and showed that the epitaxial films retained a higher hardness, compared to textured ZrB2 films and bulk, also at these temperatures.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. 67 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1744
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-128614 (URN)10.3384/diss.diva-128614 (DOI)978-91-7685-833-2 (Print) (ISBN)
Public defence
2016-06-17, Planck, Fysikhuset, Campus Valla, Linköping, 09:15 (English)
Opponent
Supervisors
Available from: 2016-05-25 Created: 2016-05-25 Last updated: 2016-08-31Bibliographically approved

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Tengdelius, LinaLu, JunForsberg, UrbanLi, XunHultman, LarsJanzén, ErikHögberg, Hans
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Journal of Crystal Growth
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