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Atomic-layer-resolved bandgap structure of an ultrathin oxynitride-silicon film epitaxially grown on 6H-SiC(0001)

T. Shirasawa, K. Hayashi, H. Yoshida, S. Mizuno, S. Tanaka, T. Muro, Y. Tamenori, Y. Harada, T. Tokushima, Y. Horikawa, E. Kobayashi, T. Kinoshita, S. Shin, T. Takahashi, Y. Ando, K. Akagi, S. Tsuneyuki, and H. Tochihara
Phys. Rev. B 79, 241301(R) – Published 1 June 2009

Abstract

Electronic structures of a silicon-oxynitride (SiON) layer (0.6nm in thickness) epitaxially grown on 6H-SiC(0001) were investigated on atomic-layer scale using soft x-ray absorption spectroscopy and x-ray emission spectroscopy (XAS and XES) and first-principles calculations. The SiON layer has a hetero-double-layered structure: an interfacial silicon nitride layer and a silicon oxide overlayer. The element-specific XAS and XES measurements revealed layer-resolved energy-band profiles. Measured gap sizes are 6.3±0.6eV at the nitride layer and 8.3±0.8eV at the oxide layer. The nitride and oxide layers have almost the same energy of conduction-band minimum (CBM) being 3eV higher than CBM of the SiC substrate. The energy-band profiles of the SiON layer are qualitatively reproduced by the calculations. The calculations show that broadening of bandgap of the substrate occurs only at an interfacial SiC bilayer.

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  • Received 19 December 2008

DOI:https://doi.org/10.1103/PhysRevB.79.241301

©2009 American Physical Society

Authors & Affiliations

T. Shirasawa1,*, K. Hayashi2, H. Yoshida2, S. Mizuno2, S. Tanaka3, T. Muro4, Y. Tamenori4, Y. Harada5, T. Tokushima5, Y. Horikawa5, E. Kobayashi6, T. Kinoshita4, S. Shin1,5, T. Takahashi1, Y. Ando7, K. Akagi7,8, S. Tsuneyuki1,7,†, and H. Tochihara2,‡

  • 1Institute for Solid State Physics, University of Tokyo, Chiba 277-8581, Japan
  • 2Department of Molecular and Material Sciences, Kyushu University, Fukuoka 816-8580, Japan
  • 3Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka 819-0395, Japan
  • 4SPring-8, JASRI, Sayo-gun, Hyogo 679-5148, Japan
  • 5SPring-8, RIKEN, Sayo-gun, Hyogo 679-5148, Japan
  • 6SAGA-LS, Tosu, Saga 841-0005, Japan
  • 7Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
  • 8WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan

  • *sirasawa@issp.u-tokyo.ac.jp
  • stsune@phys.s.u-tokyo.ac.jp
  • tochihar@mm.kyushu-u.ac.jp

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Issue

Vol. 79, Iss. 24 — 15 June 2009

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