Studies in atomic-scale control of functional titanium nitride thin films by reflection high energy electron diffraction
| Project/Area Number |
11650713
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
KASUKABE Yoshitaka Tohoku University, Interntional Student Center, Associate Professor, 留学生センター, 助教授 (30194749)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Yukio Tohoku University, School of Engineering, Professor, 大学院・工学研究科, 教授 (60005816)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Keywords | N-implantation / Titanium nitride / hcp-fcc transformation / reflection high energy electron diffraction / in-situ observation / transmission electron microscopy / molecular orbital calculations / electron energy loss spectroscopy / 蒸着チタン薄膜 |
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| Research Abstract |
Titanium nitride, TiN, has covalent as well as metallic and ionic properties, which make it fascinating for both technological applications such as diffusion barriers in microcircuits, and fundamental research. In order to investigate the interesting physical properties of TiN films, in-situ observations of the growth of TiN films are more feasible. Although it has been recently reported in light of ex-situ experiments that TiN films could be epitaxially grown by N-implantation into Ti films evaporated on NaCl substrates at room temperature, knowledge of changes in the crystallographic and electronic structures during nitriding Ti films, is incomplete. Thus, nitrogen ions (N_2^+) with 62 keV were implanted into evaporated-Ti films in the 400 kV analytical and high resolution transmission electron microscopy (TEM) combined with ion accelerators. Observations by in-situ TEM equipped with electron energy loss spectroscopy and reflection high energy electron diffraction, along with the discrete variational Xα molecular orbital calculations, revealed changes in the crystallographic and electronic structures of evaporated-Ti films due to N-implantation. A (001)-oriented NaCl-type TiN_y is epitaxially formed by the transformation of (03 5)-oriented hcp-Ti to (001)-oriented fcc-Ti and by the occupation of N in the octahedral (O-) sites, whereas a (110)-oriented TiN_y is formed by nitriding a (110)-oriented TiH_x. The release of H from the TiH_x occurs preferentially rather than the occupation of N in the O-sites of fcc-Ti sublattice. The loss peak due to volume plasmon of areas where TiH_x has grown in the as-grown Ti film shifts to lower loss energy in the early N-implanting stage, while that of areas, where hcp-Ti has grown, gradually shifts to higher loss energies with increasing N dose. Analysis of Mulliken bond overlap populations determines that occupation of N in the O-sites gives rise to weakening Ti-Ti bonds and formation of Ti-N covalent bonds.
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Report
(3 results)
Research Products
(7 results)
