2021 Fiscal Year Research-status Report
Controlling the polarity of ScAlN via formation of cation/anion vacancy
| Project/Area Number |
21K04168
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| Research Institution | National Institute of Advanced Industrial Science and Technology |
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Principal Investigator |
Anggraini SriAyu 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, 研究員 (80784123)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | piezoelectric / thin films / nitride / ScAlN / polarity / defect / sputtering / vacancy |
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| Outline of Annual Research Achievements |
I have fabricated ScAlN doped with each of element in group IVB, i.e carbon (c), silicon (Si), germanium (Ge) and tin (Sn) via sputtering method on Si(100). It was found that alloying ScAlN with either Si or Ge or Sn within a particular concentration range could inverse the polarity from Al-polar to N-polar. It is also important to keep the concentration of Sc less than 40 at.%, since addition of each of those elements into Sc0.4Al0.6N yielded in the formation of thin films with Al-polarity, which means no polarity inversion occurred. Unfortunately alloying ScAlN with C was unable to inverse the polarity of the thin films, since the ScCAlN was confirmed to have Al-polarity. The ratio of Sc to Si/Ge/Sn is also an important factor that affect the polarity of the resulting thin film.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The first objective of this proposal is to inverse the polarization direction of ScAlN by using doping with other element to control the concentration of cation or anion vacancy. Since doping with element that has higher oxidation state than Sc3+ or Al3+ is predicted to form cation vacancy (aluminum vacancy), my first plan is to alloy ScAlN with element that has oxidation state of 4+, i.e. carbon (C), Si, Ge, tin (Sn)) in FY 2021. By conducting this, I can investigate the effect of cation vacancy on polarity inversion in ScAlN. This year, I have successfully prepared ScCAlN, ScSiAlN, ScGeAlN, ScSnAlN thin films and confirmed the change in polarity in the resulting thin films. In other words, my research progressed in accordance with the plan.
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| Strategy for Future Research Activity |
This proposal aims to control the polarization direction of ScAlN piezoelectric thin films by forming cation vacancy via doping with element with oxidation state of 4+, i.e. C, Si, Ge, Sn and by introducing anion vacancy via doping with element with oxidation state of 2+, i.e. Mg, Ni, Cu, Zn. We have fabricated thin films that are expected to have cation vacancy. The next plan is to synthesize ScY-doped-AlN (Y is 2+ cation = Mg, Cu, Ni, Zn) The purpose of this addition is to investigate the effect of anion vacancy, i.e. nitrogen vacancy (VN) via doping with element that has lower oxidation state than Al3+ or Sc3+. Theoretically, addition of element with oxidation of 2+ such as Mg, Cu, Ni or Zn is expected to generate nitrogen vacancy (VN).
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| Causes of Carryover |
I planned to use the budget for traveling to attend conferences. However due to covid pandemic all conferences was conducted online, which is why there is a certain amount of money that is not being used. However the travel restriction in Japan as well as some countries has been relaxed from this fiscal year, so I plan to use it to travel so I can attend the conference on-site.
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| Remarks |
I was awarded a best poster award in The 82rd JSAP Autumn Meeting 2021
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Research Products
(3 results)
