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arXiv:2608.07127

Niobium Titanium Nitride as a High Tensile Stress Material for Nanomechanics

Korbinian Rubenbauer, Burak E. Bülbüloglu, Thomas Luschmann, Manuel Müller, Stephan Geprägs, Witlef Wieczorek, Eva M. Weig, Matthias Althammer, Hans Huebl

quant-phcond-mat.mtrl-sciSubmitted Aug 7, 2026• Announced Aug 10, 2026
arXivHTMLPDF

Abstract

Over the past decades, high-coherence mechanical resonators have been continuously pushed to new limits, using techniques such as dissipation dilution and clamp-tapering to enhance their quality factor beyond intrinsic material limitations. Today, these mechanical resonators are often fabricated from silicon-nitride, silicon-carbide or aluminum. Recently, however, interest in novel material platforms has grown, especially those allowing for the integration within superconducting circuits. Among these, superconducting nitrides stand out as particularly promising due to their high transition temperatures compared to elementary superconductors. Here, we introduce them as nanomechanical resonators and report on the fabrication and characterization of highly stressed, doubly clamped niobium titanium nitride (NbTiN) nanostring resonators. Using optical interferometry, we determine the elastic properties and mechanical quality factor from room temperature to 13 K. We observe high tensile stress up to 0.81 GPa along with a Young's modulus of 181 GPa and an intrinsic mechanical quality factor up to 850. With these favorable mechanical properties, NbTiN constitutes a promising material platform for future applications in cavity electro- and nanomechanics.

Comments
9+2 pages, 4+2 figures, 1+0 tables

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Over the past decades, high-coherence mechanical resonators have been continuously pushed to new limits, using techniques such as dissipation dilution and clamp-tapering to enhance their quality factor beyond intrinsic material limitations. Today, these mechanical resonators are often fabricated from silicon-nitride, silicon-carbide or aluminum. Recently, however, interest in novel material platforms has grown, especially those allowing for the integration within superconducting circuits. Among these, superconducting nitrides stand out as particularly promising due to their high transition temperatures compared to elementary superconductors. Here, we introduce them as nanomechanical resonators and report on the fabrication and characterization of highly stressed, doubly clamped niobium titanium nitride (NbTiN) nanostring resonators. Using optical interferometry, we determine the elastic properties and mechanical quality factor from room temperature to 13 K. We observe high tensile stress up to 0.81 GPa along with a Young's modulus of 181 GPa and an intrinsic mechanical quality factor up to 850. With these favorable mechanical properties, NbTiN constitutes a promising material platform for future applications in cavity electro- and nanomechanics.
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Titanium nitride is an attractive material for a range of superconducting quantum-circuit applications owing to its low microwave losses, high surface inductance, and chemical stability. The physical properties and device performance, nevertheless, depend strongly on the quality of the materials. In this paper, we focus on the highly crystalline and epitaxial titanium nitride thin films deposited on sapphire substrates using magnetron sputtering at an intermediate temperature (${300}^{\ensuremath{\circ}}\mathrm{C}$). We performed a set of systematic and comprehensive material characterizations to thoroughly understand the structural, chemical, and transport properties. Microwave losses at low temperatures were studied using patterned microwave resonators, where the best internal quality factor in the single-photon regime is measured to be $3.3\ifmmode\times\else\texttimes\fi{}{10}^{6}$ and that in the high-power regime $>1.0\ifmmode\times\else\texttimes\fi{}{10}^{7}$. Adjusted with the material filling factor of the resonators, the microwave loss-tangent here compares well with the previously reported best values for superconducting resonators. This work lays the foundation of using epitaxial titanium nitride for low-loss superconducting quantum circuits.
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Abstract We systematically study the performance of compact lumped element planar microwave Nb70Ti30N (NbTiN) resonators operating at 5 GHz in external in-plane magnetic fields up to 440 mT, a broad temperature regime from 2.2 K up to 13 K, as well as mK temperatures. For comparison, the resonators have been fabricated on thermally oxidized and pristine, (001) oriented silicon substrates. When operating the resonators in the multi-photon regime at T = 2.2 K, we find internal quality factors Q int ≃ 2 × 105 for NbTiN resonators grown on pristine Si substrates. In addition, we investigate the Q-factors of the resonators on pristine Si substrates at millikelvin temperatures to assess their applicability for quantum applications. We find Q int ≃ 2 × 105 in the single photon regime and Q int ≃ 5 × 105 in the high power regime at T = 7 mK. From the excellent performance of our resonators over a broad temperature and magnetic field range, we conclude that NbTiN deposited on Si (100) substrates, where the surface oxide has been removed, constitutes a promising material platform for electron spin resonance and ferromagnetic resonance experiments using superconducting planar microwave resonators.
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