Formation of inorganic electride thin films via site-selective extrusion by energetic inert gas ions
- Frontier Collaborative Research Center, P.O. Box S2-13, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)
Inert gas ion implantation (acceleration voltage 300 kV) into polycrystalline 12CaO{center_dot}7Al{sub 2}O{sub 3} (C12A7) films was investigated with fluences from 1x10{sup 16} to 1x10{sup 17} cm{sup -2} at elevated temperatures. Upon hot implantation at 600 deg. C with fluences greater than 1x10{sup 17} cm{sup -2}, the obtained films were colored and exhibited high electrical conductivity in the as-implanted state. The extrusion of O{sup 2-} ions encaged in the crystallographic cages of C12A7 crystal, which leaves electrons in the cages at concentrations up to {approx}1.4x10{sup 21} cm{sup -3}, may cause the high electrical conductivity. On the other hand, when the fluence is less than 1x10{sup 17} cm{sup -2}, the as-implanted films are optically transparent and electrically insulating. The conductivity is enhanced and the films become colored by irradiating with ultraviolet light due to the formation of F{sup +}-like centers. The electrons forming the F{sup +}-like centers are photo released from the encaged H{sup -} ions, which are presumably derived from the preexisting OH{sup -} groups. The induced electron concentration is proportional to the calculated displacements per atom, which suggests that nuclear collision effects of the implanted ions play a dominant role in forming the electron and H{sup -} ion in the films. The hot ion implantation technique provides a nonchemical process for preparing electronic conductive C12A7 films.
- OSTI ID:
- 20664995
- Journal Information:
- Journal of Applied Physics, Vol. 97, Issue 2; Other Information: DOI: 10.1063/1.1829151; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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