Scanning tunneling microscopy/spectroscopy on superconducting diamond films

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


研究成果: Article査読

1 被引用数 (Scopus)


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.

ジャーナルNew Diamond and Frontier Carbon Technology
出版ステータスPublished - 2007 8月 2

ASJC Scopus subject areas

  • 材料科学一般
  • 表面および界面
  • 表面、皮膜および薄膜


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