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Enhanced Conductivity and Microstructure in Highly Textured TiN1–x/c-Al2O3 Thin Films

Zintler, Alexander ; Eilhardt, Robert ; Petzold, Stefan ; Sharath, Sankaramangalam Ulhas ; Bruder, Enrico ; Kaiser, Nico ; Alff, Lambert ; Molina-Luna, Leopoldo (2022):
Enhanced Conductivity and Microstructure in Highly Textured TiN1–x/c-Al2O3 Thin Films. (Publisher's Version)
In: ACS Omega, 7 (2), pp. 2041-2048. ACS Publications, ISSN 2470-1343,
DOI: 10.26083/tuprints-00021222,
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Item Type: Article
Origin: Secondary publication via sponsored Golden Open Access
Status: Publisher's Version
Title: Enhanced Conductivity and Microstructure in Highly Textured TiN1–x/c-Al2O3 Thin Films
Language: English
Abstract:

Titanium nitride thin films are used as an electrode material in superconducting (SC) applications and in oxide electronics. By controlling the defect density in the TiN thin film, the electrical properties of the film can achieve low resistivities and a high critical temperature (Tc) close to bulk values. Generally, low defect densities are achieved by stoichiometric growth and a low grain boundary density. Due to the low lattice mismatch of 0.7%, the best performing TiN layers are grown epitaxially on MgO substrates. Here, we report for the first time a Tc of 4.9 K for ultrathin (23 nm), highly textured (111), and stoichiometric TiN films grown on 8.75% lattice mismatch c-cut Al₂O₃ (sapphire) substrates. We demonstrate that with the increasing nitrogen deficiency, the (111) lattice constant increases, which is accompanied by a decrease in Tc. For highly N deficient TiN thin films, no superconductivity could be observed. In addition, a dissociation of grain boundaries (GBs) by the emission of stacking faults could be observed, indicating a combination of two sources for electron scattering defects in the system: (a) volume defects created by nitrogen deficiency and (b) defects created by the presence of GBs. For all samples, the average grain boundary distance is kept constant by a miscut of the c-cut sapphire substrate, which allows us to distinguish the effect of nitrogen deficiency and grain boundary density. These properties and surface roughness govern the electrical performance of the films and influence the compatibility as an electrode material in the respective application. This study aims to provide detailed and scale-bridging insights into the structural and microstructural response to nitrogen deficiency in the c-Al₂O₃/TiN system, as it is a promising candidate for applications in state-of-the-art systems such as oxide electronic thin film stacks or SC applications.

Journal or Publication Title: ACS Omega
Journal volume: 7
Issue Number: 2
Publisher: ACS Publications
Classification DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
600 Technik, Medizin, angewandte Wissenschaften > 660 Technische Chemie
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Advanced Electron Microscopy (aem)
Forschungsfelder > Matter and Materials
Date Deposited: 11 May 2022 13:14
Last Modified: 11 May 2022 13:14
DOI: 10.26083/tuprints-00021222
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-212220
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/21222
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