Single-crystal aluminum superconducting ultra-thin films grown on GaAs(111)A with low twin ratios and the impact on microwave properties

ORAL

Abstract

The disordered grain boundaries of superconducting thin films and interface inhomogeneity to adjacent layers are sources of energy relaxation channels that limit the performance of superconducting quantum devices. In this work, we have demonstrated single-crystal aluminum (Al) ultra-thin films on GaAs(111)A substrates with high crystallinity and very low twin ratios. The transport properties of these Al films were measured to characterize the thin-film quality.

Synchrotron radiation X-ray diffraction scans on the Al films with thickness from 1.5 to 20 nm exhibited clear Pendellösung fringes. The full width at half maximum (FWHM) of θ-rocking curves of the Al films is 0.018°-0.027°. The in-plane scans revealed that the Al(111) films have low twin ratios, and the FWHM of in-plane Al(111̅) peaks is very low of 0.76°-1.88°. The surface morphology characterized by atomic force microscopy is smooth and exhibits terrace steps. The scanning transmission electron microscopy images have revealed the atomically sharp Al/GaAs interface. These nm-thick Al films exhibited high residual resistance ratios from 1.11 to 4.46, indicating the high quality of Al films with low twin ratios. Microstrip resonators were fabricated using these ultra-thin Al films to measure the internal quality factors. Such single-crystal Al is a potential candidate for building high-coherence superconducting quantum circuits.

The support from the Natl. Sci. Technol. Council in Taiwan through NSTC 112-2119-M-007-009 is acknowledged.

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Presenters

  • Hsien-Wen Wan

    • Graduate Institute of Applied Physics and Dept. of Physics, National Taiwan University
    • Graduate Institute of Applied Physics and Department of Physics, National Taiwan University
    • National Taiwan University

Authors

  • Hsien-Wen Wan

    • Graduate Institute of Applied Physics and Dept. of Physics, National Taiwan University
    • Graduate Institute of Applied Physics and Department of Physics, National Taiwan University
    • National Taiwan University

  • Yi-Ting Cheng

    • National Tsing Hua University
    • Department of Physics, National Tsing Hua University

  • Chao-Kai Cheng

    • Graduate Institute of Applied Physics and Dept. of Physics, National Taiwan University
    • National Taiwan University
    • Graduate Institute of Applied Physics and Department of Physics, National Taiwan University

  • Jui-Min Chia

    • Department of Physics, National Tsing Hua University

  • Chien-Ting Wu

    • Taiwan Semiconductor Research Institute

  • Chia-Hung Hsu

    • National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
    • Scientific Research Division, NSRRC, Hsinchu
    • National Synchrotron Radiation Research Center

  • Sheng-Shiuan Yeh

    • International College of Semiconductor Technology, National Yang Ming Chiao Tung University

  • Yen-Hsiang Lin

    • Natl Tsing Hua University
    • National Tsing Hua University
    • Department of Physics, National Tsing Hua University

  • Jueinai Kwo

    • National Tsing Hua University
    • Department of Physics, National Tsing Hua University
    • Natl Tsing Hua Univ

  • Minghwei Hong

    • National Taiwan University
    • Graduate Institute of Applied Physics and Dept. of Physics, National Taiwan University
    • Graduate Institute of Applied Physics and Department of Physics, National Taiwan University
    • Natl Taiwan Univ