2018 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 | Tip enhancement / Terahertz / Low temperature |
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| Outline of Annual Research Achievements |
Two major activities were done in this fiscal year: (1) construction of a terahertz-time domain spectroscopy (THz-TDS) setup and (2) studying the tip-enhancement effect in the near infrared range. First a setup has been completed THz-TDS. The setup consists of an indium arsenide surface emitter and a low temperature grown gallium arsenide (LT-GaAs) photoconductive antenna The setup utilizes a delay stage as well as lockin amplifier. The software for the setup was written in LabVIEW so that several changes can be made according to the needs in the future. The results produced in our self-made THz-TDS setup has been compared to available literature and it was found that the results are on-par and at times even better than what has been reported before in terms of sensitivity and intensity. This setup has been used to check the THz emission properties of a LT-GaAs surface emitter. The results of this experiment are currently being prepared for a publication. All of these experiments are performed in ambient conditions. Since we intend to apply this technique to low temperatures in the future for better stability, tip-enhancement effect in the near infrared range was also studied in this fiscal year. We performed tip enhanced Raman spectroscopy experiment in order to assess the best way for introducing the THz beam into the low temperature scanning tunneling microscope. In this experiment, sub-nanometer spatial resolution of tip enhanced spectroscopy was achieved using the setup developed. The results of these experiments have been submitted to a journal.
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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 project has so far progressed according to the schedule. The terahertz spectroscopy has been developed in this year and also, tip enhancement effect using a gold tip has been demonstrated.
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| Strategy for Future Research Activity |
In the coming fiscal year, THz beam will be introduced to the tip-sample junction. Consequently, tip-enhancement effect will also be continuously investigated both in ambient and low temperature conditions.
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| Causes of Carryover |
Although a THz-TDS setup has been successfully developed in this fiscal year, I planned purchase a a redesigned THz emitter and THz detector in order to achieve a more sensitive setup in the end of last year. However, upon discussion with Prof. Masahiko Tani of FIR center in Fukui university, I decided to reconsider my design and will purchase this item as well as the necessary accessories instead this year. Apart from the new emitter and detector, in the next fiscal year, the budget will be used to procure a controller for the delay stage and also additional optics for the terahertz setup.
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