| Project/Area Number |
17360009
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Institute of Symbiotic Science and Technology ; Tokyo University of Agriculture and Technology |
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Principal Investigator |
SATO Katsuaki Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Professor, 大学院共生科学技術研究院, 教授 (50170733)
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| Co-Investigator(Kenkyū-buntansha) |
MORISHITA Yoshitaka Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor, 大学院共生科学技術研究院, 助教授 (00272633)
ISHIBASHI Takayuki Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor, 大学院共生科学技術研究院, 助手 (20272635)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,700,000 (Direct Cost: ¥15,700,000)
Fiscal Year 2006: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2005: ¥13,900,000 (Direct Cost: ¥13,900,000)
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| Keywords | ternary magnetic semiconductor / Molecular beam epitaxy / MnGeP_2 / MnP / magnetic tunnel junction / magnetoresistance / nanowhisker / self-catalytic growth / MnGeP_2 / 室温磁性半導体 / トンネル接合 / 微細加工 |
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| Research Abstract |
This report describes achievements of the research project "Fabrication of Tunneling Magneto-resistance Devices using Novel Room-temperature Ferromagnetic Semiconductor MnGeP2" conducted under the support of the Grant-in-Aid for Scientific Research from Japan Society for Promotion of Science for 2005-2006 FY, Category (B) (2), No.17360009.
The purpose of this project is to elucidate the optimum fabrication condition of MnGeP2 films which was discovered during the research for chalcopyrite-type room-temperature ferromagnetic semiconductors conducted under the 2001-2003 FY Grant-in-Aid for Scientific Research of MEXT-JSPS, and fabricate tunneling magneto-resistance (TMR) devices using these films.
For realization of TMR devices it is essential to prepare magnetic films with improved flatness. However, MnGeP2 films prepared on GaAs and InP substrates suffer poor surface morphology with roughness and were found to be unsuitable for tMR devices. To improve surface flatness we introduced Ge bu
… More
ffer layer, which proved to be effective. However, it is found by TEM and EDX observation that MnP grains are mixed among MnGeP2 texture.
In order to suppress phase separation we raised the substrate temperature following the first principle thermodynamic calculation. The resulting films, however, showed no spontaneous magnetization at room temperature, despite that the films are in single phase state. We therefore changed the strategy and started to exploit optimum conditions to obtain MnP thin films with sufficient flatness, since the magnetic properties of MnP has been well known.
Using MnP and CoFe as electrodes we prepared magnetic tunnel junctions which showed magneto-resistance effect. Thus we have established a technique to obtain MTJ consisting of MnGeP2.
In addition, during preparation of high quality MnGeP2 films at elevated substrate temperatures we have found self-assembled growth of nanometer-sized whiskers on the surface of the substrates by careful SEM observations. By TEM observations and compositional analyses whiskers are found to be either Ge-based or MnP based crystals. Catalyst-free growth of nano-whiskers is of interest since most of previous report used Au as catalyst. Therefore the results are included in this report although this finding is not a main subject of this research program. Less
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