2005 Fiscal Year Final Research Report Summary
Study of vacancy-type defects in metal/metal-oxide by means of positron annihilation
| Project/Area Number |
16560574
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Physical properties of metals
|
|---|
| Research Institution | University of Tsukuba |
|---|
Principal Investigator |
UEDONO Akira University of Tsukuba, Graduate school of pure and applied sciences, Associate professor, 大学院・数理物質科学研究科, 助教授 (20213374)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YAMABE Kikuo University of Tsukuba, Graduate School of Pure and Applied Sciences, Professor, 大学院・数理物質科学研究科, 教授 (10272171)
|
|---|
| Project Period (FY) |
2004 – 2005
|
| Keywords | metal-oxide / interface / vacancy-type defect / positron annihilation |
|---|
| Research Abstract |
The measure target of the research project is the study of vacancy-type defects (especially oxygen vacancies) in metal oxides and the diffusion of atoms and vacancies introduced by the formation of metal/metal-oxide interface.
SiO_2/Si fabricated by thermal oxidation and metal/SrTiO_3 structures were characterized. It was found that the electrical properties of SiO_2/Si were degraded by the deposition of Al on SiO_2 films. By using monoenergetic positron beams, electron or hole traps were introduced by the Al deposition and as a results the formation probability of positronium (Ps) was suppressed by the trapping of positron or spur electrons by such traps. The degradation of the electrical properties of MOS structures investigated in the present study is mainly due to the diffusion of oxygen atoms into Al films.
HfO_2 and HfON thin films were deposited on Si substrates and TiN was deposited to form MOS structures. Measurements of the Doppler broadening spectra of annihilation radiation and the lifetime spectra of positrons indicated that positrons annihilated from the trapped state by open volumes that exist intrinsically in amorphous structures of the films. From the analysis of the data, negative charges were found to present near the high/Si interface. When the TiN films were deposited using CVD, no large change in the electric field in the Si substrate was observed. When the films were deposited using PVD, however, positron were repelled from the interfaces, suggesting the introduction of positive charges by the formation of oxygen vacancies.
We confirmed that the positron annihilation parameter is sensitive to the defects in metal/oxide-metal structure, and it can be used to potential tool for the investigation of metal/oxide-metal interface.
|
Research Products
(20 results)
