Issue 31, 2023

Chemical potential gradient induced formation of Kirkendall voids at the epitaxial TiN/MgO interface

Abstract

We report the observation of Kirkendall voids at the epitaxial titanium nitride (TiN)/magnesium oxide(MgO)(001) interface. While epitaxial growth of TiN on MgO has been known for years, many reports show a perfectly sharp epitaxial interface. Because TiN is a prototypical diffusion barrier material, observing the consequence of rapid diffusion at a TiN interface is interesting. Structural characterization of the interface using X-ray diffraction and electron microscopy confirms the diffuse nature of the interface. Rectangular voids that form at the TiN/MgO(001) interface and extend into both TiN and MgO result from a large chemical potential gradient at the interface, which contributes a strong chemical driving force for diffusion. The spatial localization of the observed voids is limited to within ∼10 nm from the interface, consistent with a chemical potential gradient driving force. A composition gradient on the nanometer scale is also observed. Observation of Kirkendall voids at this nitride/oxide interface suggests possibilities for engineering oxygen and nitrogen vacancies at thin film interfaces.

Graphical abstract: Chemical potential gradient induced formation of Kirkendall voids at the epitaxial TiN/MgO interface

Article information

Article type
Paper
Submitted
21 Apr 2023
Accepted
24 Jul 2023
First published
27 Jul 2023

Nanoscale, 2023,15, 13086-13093

Author version available

Chemical potential gradient induced formation of Kirkendall voids at the epitaxial TiN/MgO interface

X. Zhang, W. J. Meng and A. C. Meng, Nanoscale, 2023, 15, 13086 DOI: 10.1039/D3NR01860A

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