Valence band electronic structures of heavily boron-doped superconducting diamond studied by synchrotron photoemission spectroscopy

Takayoshi Yokoya, Tetsuya Nakamura, Tomohiro Matsushita, Takayuki Muro, Eiji Ikenaga, Masaaki Kobata, Keisuke Kobayashi, Yoshihiko Takano, Masanori Nagao, Tomohiro Takenouchi, Hiroshi Kawarada, Tamio Oguchi

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4 Citations (Scopus)

Abstract

The valence band electronic structures of heavily boron-doped superconducting diamond films made by microwave plasma-assisted chemical vapor deposition (MPCVD) were investigated by hard X-ray photoemission spectroscopy (HXPES) and soft X-ray angle-resolved photoemission spectroscopy (SXARPES). The HXPES core-level spectrum of heavily boron-doped diamond shows a new feature at the lower binding energy side of the C 1s main peak. The HXPES valence band spectrum of a heavily boron-doped superconducting diamond film shows a broader spectral shape than that of a lightly doped non-superconducting sample. The SXARPES results of homoepitaxial CVD films show clear valence band dispersions with a bandwidth of ∼23 eV and the top of the valence band at the Γ point in the Brillouin zone, which are well explained by the calculated valence band dispersions of pure diamond. Boron concentration-dependent band dispersions near the Fermi level (EF) by SXARPES exhibit a systematic shift in EF, indicating electron depopulation due to hole doping, and an increase in the line shape corresponding to the broader density of states observed by HXPES. These results indicate that holes in the top of the valence band are responsible for the metallic states leading to superconductivity at low temperatures. The HXPES C 1s core-level spectra of lightly boron-doped non-superconducting and heavily boron-doped superconducting films are also shown.

Original languageEnglish
Pages (from-to)11-20
Number of pages10
JournalNew Diamond and Frontier Carbon Technology
Volume17
Issue number1
Publication statusPublished - 2007 Aug 2
Externally publishedYes

Keywords

  • Band structure
  • Diamond
  • Heavily boron-doped
  • Hole
  • HXPES
  • Superconductivity
  • SXARPES

ASJC Scopus subject areas

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

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    Yokoya, T., Nakamura, T., Matsushita, T., Muro, T., Ikenaga, E., Kobata, M., Kobayashi, K., Takano, Y., Nagao, M., Takenouchi, T., Kawarada, H., & Oguchi, T. (2007). Valence band electronic structures of heavily boron-doped superconducting diamond studied by synchrotron photoemission spectroscopy. New Diamond and Frontier Carbon Technology, 17(1), 11-20.