2020 Fiscal Year Research-status Report
Ultra-high performance and environment-friendly micro-energy harvesters towards self-powered micro/nano-systems for the Internet of Things
| Project/Area Number |
20K15146
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
LE VANMINH 東北大学, 未来科学技術共同研究センター, 助教 (60765098)
|
|---|
| Project Period (FY) |
2020-04-01 – 2022-03-31
|
| Keywords | Energy harvester / piezoelectric thin films / lead-free piezoelectric / Nitride piezoelectrics / Piezo MEMS / Piezoelectric devices / Power MEMS / Internet of Things |
|---|
| Outline of Annual Research Achievements |
The main objectives of the project are to integrate novel high-power-figure-of-merit (FoM) piezoelectric nitride films and nonlinearity-operating architecture to create ultra-high performance and environment-friendly micro-energy harvesters (micro-EHs). The first year was therefore devoted to (i) development of high-FoM Sc-free-doped AlN films, (ii) the films’ characterization, (iii) establishing key microfabrication process, and (iv) the numerical model for piezoelectric nonlinear micro-EHs has been established.
A magnetron AC sputter (AMS) with the host Al and additional Ta targets has been completely set up. Ta-doped AlN films were grown successfully on Pt/Ti/AlN/Si wafers. The highly c-axis films with FWHM of below 3 deg were obtained. The films had a low loss tangent of 0.02, a permittivity of 18, and a leakage current of 0.2x10-6 A/cm2 at 500 kV/cm. For evaluating the FoM and establishing the microfabrication process, the micromachined linear EHs that composed a Ta-doped AlN/Si cantilever and a proof mass had been successfully fabricated. Micromachining Ta-doped AlN films was well established by a Cl-based ICP-RIE system with an etching rate of 200 nm/min. The evaluation showed that the FoMxQ2 (Q: quality factor) of 13x106 GPa was 8 times higher than the best of the pure AlN (1.6 x 106 GPa). The results contributed to the high-power density of 13.7 mW/cm3 at 1 g (g = 9.89 m/s2) that even was comparable with the best of the highly 43-at.%-Sc-doped AlN harvesters (15 mW/cm3). In parallel, the numerical model simulation for nonlinear micro-EHs were complete.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Due to the covid-19 pandemic, some periods were blocked to conduct experiments, especially for common-use facilities. Therefore, instead of conducting the research project in sequence as the initial plan, the orders of the tasks were adjusted based on the situation. For example, the analytical and numerical models for nonlinear energy harvester that were planned for the second year were established in advance during the blocked period. Also, I strongly exploited our lab facilities to conduct experiments since conducting experiments alone was still permitted. Hence, the key microfabrication for etching the developed piezoelectric films was also complete. As the result, the research progress is still under the control. The initial achievement was distinguished by the oral presentation at the 2021 IEEE 34th International Conference on Micro Electro Mechanical Systems (MEMS).
|
| Strategy for Future Research Activity |
According to the initial project plan, the first half of the second year will be planned to design the broad-bandwidth nonlinear micro-energy harvesters and to establish the device microfabrication process. Since the numerical model and the key microfabrication process had been completed. I will have more time for clarifying the physical mechanism of the doping effect in correlation with the piezoelectric properties this year. In parallel, the fabrication and evaluation of the proposed broad-bandwidth nonlinear micro-energy harvesters will be started to confirm the numerical model, and the most important to experimentally realize the device that meets the project target in performance.
|
| Causes of Carryover |
The initial plan was used for attending conference. However, due to the covid-19, the online MEMS online conference with much cheaper fee (26727 yen) and no travel expense. A part of this amount (14060 yen) was used to buy the experimental items. Therefore, the incurring amount to be used next year is 359213 yen.
I would like to use this amount for the next year conference. In the case, a virtual conference will be held. The amount will be used for journal publication process and/or partial amount for the experimental expense.
|
Research Products
(1 results)
