| Project/Area Number |
21K04874
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 29020:Thin film/surface and interfacial physical properties-related
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
林 冠廷 東京大学, 生産技術研究所, 特任研究員 (70772309)
|
|---|
| Project Period (FY) |
2024-01-17 – 2025-03-31
|
| Project Status |
Granted (Fiscal Year 2024)
|
| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2023: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2022: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2021: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
|
|---|
| Keywords | 近接場光学顕微技術 / THz顕微技術 / ナノ熱計測 / 近接場顕微技術 / THz光学系 / ナノサーモグラフィー |
|---|
| Outline of Research at the Start |
To improve the SNR of passive THz s-SNOM, reducing the huge background radiation is one of the solutions. The main source of the background radiation is the 300 K plank radiation from samples and environment. Therefore, cooling down the optics and scanning probe microscope to 4.2 K is an efficient method to reduce Plank radiation in THz region. The THz near-field signal excited in non-equilibrium state is expected to be easily extracted, and the SNR will be improved. The low-temperature THz s-SNOM is expected to study the energy dissipation in device and mesoscopic transport in novel material.
|
| Outline of Annual Research Achievements |
After improving the confocal optics and introducing tip-height modulation in the low-temperature passive THz s-SNOM system, the acquisition time of near-field detection improved to 3 s from 10 s. The near-field signals observed on the NiCr can be explained by the electromagnetic evanescent fields induced by the thermal random motion of the conduction electrons.
To study the energy dissipation in graphene devices, a potential material for carbon-based electronic devices due to its ultrahigh electrical and thermal conductivity, I fabricated narrow constricted graphene devices using electron beam lithography. The CVD-grown monolayer graphene was transferred to a silica substrate. With the room-temperature passive THz s-SNOM, I measured the evanescent fields induced by excess current. The near-field signals strongly appeared in the narrow wire region with a 1 μm width. The electrons obtained large electrical energy in the narrow region due to the high electric field. The near-field signals on graphene belong to the current-induced thermal fluctuating EM evanescent fields due to the high current density, and can be explained by the fluctuation-dissipation theorem. Furthermore, a gradually diffusive thermal dissipation appears on the anode side of the wide graphene region, which is considered as an electron-phonon relaxation process.
|
