TY - JOUR
T1 - Unique behavior of F-centers in high-k Hf-based oxides
AU - Umezawa, N.
AU - Shiraishi, K.
AU - Ohno, T.
AU - Boero, M.
AU - Watanabe, H.
AU - Chikyow, T.
AU - Torii, K.
AU - Yamabe, K.
AU - Yamada, K.
AU - Nara, Y.
N1 - Funding Information:
This work was partly supported by “High-k Network” co-operating with academic, industry and governmental institutes, a program for the “Promotion of Leading Researches” in Special Coordination Funds for Promoting Science and Technology by MEXT, and a Grant-in-Aid for Scientific Research No. 16560020 by MEXT.
PY - 2006/4/1
Y1 - 2006/4/1
N2 - 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.
AB - 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.
KW - F-center
KW - HfO
KW - High-k dielectric
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U2 - 10.1016/j.physb.2005.12.101
DO - 10.1016/j.physb.2005.12.101
M3 - Conference article
AN - SCOPUS:33645154657
SN - 0921-4526
VL - 376-377
SP - 392
EP - 394
JO - Physica B: Condensed Matter
JF - Physica B: Condensed Matter
IS - 1
T2 - Proceedings of the 23rd International Conference on Defects in Semiconductors
Y2 - 24 July 2005 through 29 July 2005
ER -