| 研究実績の概要 |
Terahertz (THz) sensors are crucial components for THz technology. In this project, we propose to realize uncooled, compact, highly-sensitive and fast THz bolometers by using NMES resonators based on 2D nanomaterials. We have focused on the following work in this year.
First, from literature review, we have chosen graphene as the materials for NEMS sensors owing to its great mechanical and thermal properties, and good availability in the market.
Second, we have designed the device structure, and started the fabrication of NEMS resonators. Graphene mono-layers from a bulk graphite are transferred to a sacrificial layer on silicon substrate. Suspended graphene resonators are obtained by selectively etching the sacrificial layer. The mechanical resonance is driven by the electrostatic force from a back-gate electrode, and detected as a change in the current through the graphene layer. When the NEMS resonator is irradiated with a THz source, the resonance frequency is shifted owing to the thermal effect.
Finally, we have studied the fundamental physics of MEMS/NEMS-based THz bolometers, such as the nonlinearity, mode coupling, and combinations with metamaterials, to significantly improve the thermal sensitivity.
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| 今後の研究の推進方策 |
In the next fiscal year, we will focus on the following work to realize uncooled, sensitive and fast THz NEMS bolometric sensors.
First, we will optimize the fabrication process, and the driving and detecting schemes of NEMS resonators. The target is to obtain NEMS resonators with a high quality factor, and a low frequency noise for high sensitivity THz detection. We will also calibrate the thermal responsibility of the NEMS resonators.
Second, we will design a suitable optical coupling structure for the NEMS resonator to couple THz wave with the NEMS resonator, making it to be a THz bolometer. Then we will calibrate the optical sensitivity of fabricated NEMS bolometer.
Furthermore, to achieve a fast progress, we will consider to introduce more international collaborations in the future work.
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| 次年度使用額が生じた理由 |
There are mainly two reasons. First, we have performed evaluations for the THz source system with the demonstration machine from different companies.However, since the evaluation process and the delivery took several months, the final delivery is delayed to next fiscal year (late June, 2020). Second, affected by the spreading of COVID-19, some international travel plans were postponed or canceled.
The remained amount will be used for the payment of the THz source system, other necessary instruments and consumers, and domestic and international travelings for performing the research.
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