| 研究実績の概要 |
In this fiscal year, I obtained the STM image, STS spectra, and STM-TERS spectrum of graphene layers deposited on Au(111) surface via chemical vapor deposition prepared by our collaborator. The STM imaging reveals Moire patterns as well as honeycomb structures which are signatures of a graphene surface. The STM-TERS spectra showed the D band, 2D band as well as the G band. All of these peaks are expected for graphene. The defect-induced D band appears on the spectra although STM imaging shows no distinct defects in the vicinity. The G band showed splitting, which can be either due to defects or strain, the exact origin of which is still under investigation. Although I have successfully obtained both STM images and STM-TERS spectra, I was unable to obtain a good STS spectrum. This method requires a good STM tip which is difficult to obtain in the present sample owing to the large areas of the sample covered with impurities. During scanning, the STM tip might have picked up some of the impurities on the surface preventing the measurement of STS. In fact, both the STM imaging and the STM-TERS have been very challenging because the surface is not clean. For this sample, since it was prepared in a separate CVD chamber from the STM chamber, it had to be transported in the air. This means that the sample will inevitably pick up impurities from the outside environment. I performed simple cleaning by annealing the sample at 500oC. This reduced the number of impurities on the sample although it was very clear that there are still regions of the sample which are not clean.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
For the coming fiscal year, I plan to prepare my own samples in a UHV chamber attached to the STM. This will greatly reduce the amount of impurity on the sample because I don’t need to break the vacuum in order to introduce the sample to the STM. I envision that by doing this, more clear STM-TERS spectrum, STM images and STS spectra can finally be obtained. I will also start to build the setup in order to measure low-frequency Raman signals.
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| 今後の研究の推進方策 |
In the coming fiscal year, I will build the setup for measurement of the low frequency Raman modes of the Graphene on Au(111) sample. Apart from the measurement of the spectra itself, I will also perform Raman imaging in order to visualize the Graphene edges, grain boundaries and other nanoscale features of the sample. In line with this, protocols for sample cleaning and sample preparation will be modified according to the results of the Raman spectroscopy and imaging measurements.
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