2019 Fiscal Year Research-status Report
Development of time resolved STM-THz-TDS system for studying the ultrafast carrier dynamics of graphene
| Project/Area Number |
18K14153
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
JACULBIA RAFAEL 国立研究開発法人理化学研究所, 開拓研究本部, 基礎科学特別研究員 (40777299)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | Terahertz / Tip enhancement / Graphene |
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| Outline of Annual Research Achievements |
In this fiscal year, the main activity was to introduce the terahertz pulses generated by the photoconductive antenna to the scanning probe microscope tip. This step is one of the most critical in order to achieve the goals of this project. As THz light is invisible, a major challenge was how to align the THz light into the STM. As such, effective alignment procedure of the THz light into the tip junction was explored in this year. As a target sample, I used a small gold square deposited on a glass slide. This was chosen as opposed to a large mirror used in the previous year in order to have a sample sensitive to fine alignment. I found that this strategy was effective in achieving a better alignment. Moreover, I found found that the use of motorized mirror mounts was useful to fine tune the alignment. Apart from this protocols for the preparation of the tips was also improved in this year. Moreover, in order to achieve a higher signal, a new lockin amplifier was purchase in this year. With all these steps, a modulated signal based on the oscillation of the SPM tip was observed. With this I can say that I successfully coupled the THz light into the gold tip. After this, I investigated the tip distance dependence and found that it nicely correlates to what is shown in literature.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The planned goals for this year have been achieved so I could say that the project is proceeding smoothly.
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| Strategy for Future Research Activity |
In the next fiscal year, I will continue to optimize the experimental setup in order to obtain a better signal to noise ratio.
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| Causes of Carryover |
In the next fiscal year, several remaining parts of the setup will be purchased. This include a new power supply for the emitter, new substrate, materials for tip preparation and some optical components.
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