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Phase Identification and Ordered Vacancy Imaging in Epitaxial Metallic Ta2N Thin Films
Andrew C Lang1, D Scott Katzer2, Neeraj Nepal2
1American Society for Engineering Education Postdoctoral Fellow, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, United States.
ACS Applied Materials & Interfaces
|March 5, 2021
Summary
Epitaxial tantalum nitride films were analyzed using advanced electron microscopy. Researchers identified specific crystal phases and Ta vacancies, paving the way for new electronic and superconducting devices.
Area of Science:
- Materials Science
- Solid State Physics
- Crystallography
Background:
- Epitaxial transition metal nitrides (TMNs) are promising for integration with III-nitride semiconductors.
- Distinguishing between similar crystal structures of TMNs, like tantalum nitrides, is challenging with conventional methods.
Purpose of the Study:
- To definitively identify the phase of tantalum nitride films.
- To investigate the structural characteristics of molecular beam epitaxy-grown films.
- To explore the potential of TMNs for advanced electronic and superconducting devices.
Main Methods:
- High-resolution transmission electron microscopy (HRTEM).
- Aberration-corrected scanning transmission electron microscopy (AC-STEM).
- Analysis of molecular beam epitaxy (MBE)-grown gamma-tantalum nitride (γ-Ta2N) films on SiC substrates.
Main Results:
- Definitive phase identification of γ-Ta2N films was achieved.
- Films were found to be threading dislocation-free and Ta-deficient.
- Ordered tantalum (Ta) vacancy planar defects were observed, explaining the substoichiometry.
Conclusions:
- Advanced electron microscopy is crucial for precise phase identification of TMNs.
- The identified Ta vacancies offer opportunities for novel planar structures.
- These findings are foundational for developing epitaxial TMNs in electronic and superconducting applications.
