Development of quasi-2D Si devices with large magnetoresistance
| Project/Area Number |
21K04822
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 28020:Nanostructural physics-related
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| Research Institution | National Institute of Advanced Industrial Science and Technology |
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Principal Investigator |
Aurelie Spiesser 国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 主任研究員 (90793513)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Project Status |
Granted (Fiscal Year 2022)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2023: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2022: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2021: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Keywords | silicon spintronics / magnetic tunnel contact / spin transport / thin channel / novel tunnel barrier / Si spintronics / Spin transport / Magnetic tunnel contacts / Thin channel / magnetic tunnel contacts / magnetoresistance / 2-dimensional channel |
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| Outline of Research at the Start |
The aim of this project is to develop devices that exploit the spin functionality in semiconductor technology, and to apply such devices to in-memory processing. In particular, we intend to achieve large magnetic signals in Si-based spin-devices by combining the use of an ultrathin Si channel and highly-quality magnetic contacts. By focusing on quasi-2D silicon, this project builds on the knowledge and material technology developed in Si spintronics over the last decade while connecting to the global interest in 2D materials for spintronics.
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| Outline of Annual Research Achievements |
1) Spin transport in thin Si channels:
We have deposited Fe/MgO on thin silicon channels having thicknesses ranging from 70 nm to 25 nm. We used molecular beam epitaxy to grow Fe/MgO, and the RHEED patterns indicate high quality epitaxial Fe/MgO. We then fabricated devices and measured spin transport properties as a function of the Si channel thickness. We observed clear two-terminal magnetoresistance (2T-MR) for all the devices. Although an increase of the 2T-MR was observed as the Si channel thickness decreases, the resistivity of the Si channel increased with decreasing the channel thickness. This prevented us from interpreting the results in a systematic manner, as one need to keep the resistivity constant in order to compare the results.
2) Novel tunnel barrier for spin injection into Si:
We investigated the epitaxial growth of BaO on Si as a novel tunnel barrier. The BaO lattice matches that of Si better than MgO. Therefore, higher quality epitaxial BaO might be obtained on Si, and potentially be a better fit as a tunnel barrier for Si spin transport devices. We investigated different growth temperature for BaO and found the optimum growth conditions to obtain epitaxial BaO on Si.
3) Optimum contact resistance for 2T-MR in Si-based spin transport devices
The 2T-MR in spin transport devices was determined for devices with a Si channel and Fe/MgO tunnel contacts of varying MgO thickness. We showed that the optimum and scaling of the 2T-MR are profoundly affected by the variation of the spin polarization with contact resistance. The results were published in APL (2023).
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
1) Spin transport in thin Si channels:
As explained previously, the reason that we could not interpret the 2T-MR signals vs Si channel thickness comes from the different resistivity of the Si channels. We found out that the change in resistivity originates from a device fabrication problem (namely the etching of the Si channel). We are currently fabricating a new series of devices and introduced an additional step in the fabrication process to insure that the devices have a similar resistivity.
2) Novel tunnel barrier for spin injection into Si:
We are currently optimizing the growth conditions of epitaxial BaO on Si in order to obtain a very thin BaO layer on Si. So far, we could grow epitaxial BaO on Si with a thickness of 3 nm. In order to use BaO as a tunnel barrier, we need to grow a thinner barrier (<1.5 nm). This will allow us to decrease the contact resistance and potentially lead to higher 2T-MR.
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| Strategy for Future Research Activity |
1) Spin transport in thin Si channels:
After fabricating the new series of devices with thin Si channels and demonstrating large 2T-MR in ultrathin channels, we are planning to use new Si substrates that have a different resistivity. The main objective is to show the importance of the contact resistance on the magnitude of the 2T-MR. By combining thin Si channel and appropriate resistivity, we believe that we can achieved very large 2T-MR in these devices.
2) Novel tunnel barrier for spin injection into Si:
The next step is to fabricate spin transport devices with BaO and to compare spin transport properties with devices having MgO as a tunnel barrier. We believe that higher 2T-MR can be obtained using high-quality epitaxial BaO, thin channel and appropriate resistivity.
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Report
(2 results)
Research Products
(2 results)
