Unique behavior of F-centers in high-k Hf-based oxides

N. Umezawa, K. Shiraishi, T. Ohno, M. Boero, H. Watanabe, T. Chikyow, K. Torii, K. Yamabe, K. Yamada, Y. Nara

Research output: Contribution to journalConference articlepeer-review

18 Citations (Scopus)


Physical properties of F-center in HfO2 have been investigated by first-principles calculations. The F-centers (doubly occupied oxygen vacancy Vo) are found to generate gap states at 1.05 eV below the bottom of HfO2 conduction band and they are remarkably elevated by extracting electrons from the F-center. The negative-U behavior of F-centers in HfO2 is very different from those in the ionic rocksalt oxide such as MgO or CaO, which possesses positive-U character. The reason for this unique behavior of F-centers in HfO2 is considered to be due to highly positively ionized Hf4+ ions, which are largely relaxed outward away from singly occupied or non-occupied F-centers. This outward relaxation is the origin of the remarkable elevations of the F-center levels. Moreover, similar negative-U behavior is also observed in HfON.

Original languageEnglish
Pages (from-to)392-394
Number of pages3
JournalPhysica B: Condensed Matter
Issue number1
Publication statusPublished - 2006 Apr 1
EventProceedings of the 23rd International Conference on Defects in Semiconductors -
Duration: 2005 Jul 242005 Jul 29


  • F-center
  • HfO
  • High-k dielectric

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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