Scanning tunneling microscopy/spectroscopy on superconducting diamond films

Terukazu Nishizaki, Yoshihiko Takano, Masanori Nagao, Tomohiro Takenouchi, Hiroshi Kawarada, Norio Kobayashi

    Research output: Contribution to journalArticle

    1 Citation (Scopus)

    Abstract

    We report on scanning tunneling microscopy/spectroscopy (STM/STS) experiments on (111)-oriented epitaxial films of heavily boron-doped diamond grown by microwave plasma-assisted chemical vapor deposition. STM/STS measurements were performed by 3He-refrigerator-based STM under ultrahigh vacuum. The STM topography on the film surface shows microstructures with a size of ∼ 5 - 20 nm and two types of atomic structures: a hydrogenated 1×1 structure, C(111)1×1:H, and an amorphous structure. The tunneling spectra are analyzed by a modified Bardeen, Cooper, and Schrieffer (BCS) expression, and the superconducting energy gap is estimated to be Δ = 0.83 - 0.87 meV at T = 0.47 K. The obtained gap ratio 2Δ/kBTc = 3.57 - 3.7 is consistent with the weak-coupling BCS theory. The relatively large value of the broadening parameter Γ ∼ 0.38 meV is discussed in terms of the inelastic electron-scattering processes. In the low-temperature region (T = 0.47 K), the tunneling conductance spectra do not show strong spatial dependence, and superconductivity is observed independent of the surface structures. In the high-temperature region (T= 4.2 K), on the other hand, the tunneling conductance spectra show significant spatial dependence, indicating the inhomogeneous distribution of the superconducting property due to the distribution of boron atoms.

    Original languageEnglish
    Pages (from-to)21-32
    Number of pages12
    JournalNew Diamond and Frontier Carbon Technology
    Volume17
    Issue number1
    Publication statusPublished - 2007

    Fingerprint

    Superconducting films
    Boron
    Diamond films
    Scanning tunneling microscopy
    diamond films
    scanning tunneling microscopy
    Spectroscopy
    Inelastic scattering
    Diamond
    Electron scattering
    Refrigerators
    Epitaxial films
    boron
    Ultrahigh vacuum
    Superconductivity
    Surface structure
    Topography
    spectroscopy
    Chemical vapor deposition
    Diamonds

    Keywords

    • Boron-doped diamond films
    • Energy gap
    • Scanning tunneling microscopy/spectroscopy
    • Superconductivity
    • Surface structures

    ASJC Scopus subject areas

    • Surfaces, Coatings and Films
    • Surfaces and Interfaces
    • Materials Science(all)

    Cite this

    Nishizaki, T., Takano, Y., Nagao, M., Takenouchi, T., Kawarada, H., & Kobayashi, N. (2007). Scanning tunneling microscopy/spectroscopy on superconducting diamond films. New Diamond and Frontier Carbon Technology, 17(1), 21-32.

    Scanning tunneling microscopy/spectroscopy on superconducting diamond films. / Nishizaki, Terukazu; Takano, Yoshihiko; Nagao, Masanori; Takenouchi, Tomohiro; Kawarada, Hiroshi; Kobayashi, Norio.

    In: New Diamond and Frontier Carbon Technology, Vol. 17, No. 1, 2007, p. 21-32.

    Research output: Contribution to journalArticle

    Nishizaki, T, Takano, Y, Nagao, M, Takenouchi, T, Kawarada, H & Kobayashi, N 2007, 'Scanning tunneling microscopy/spectroscopy on superconducting diamond films', New Diamond and Frontier Carbon Technology, vol. 17, no. 1, pp. 21-32.
    Nishizaki, Terukazu ; Takano, Yoshihiko ; Nagao, Masanori ; Takenouchi, Tomohiro ; Kawarada, Hiroshi ; Kobayashi, Norio. / Scanning tunneling microscopy/spectroscopy on superconducting diamond films. In: New Diamond and Frontier Carbon Technology. 2007 ; Vol. 17, No. 1. pp. 21-32.
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