INSIDE the Laboratory

Information Devices Division

Nano-Photoelectronics Laboratory

Yoichi Uehara, Professor
Satoshi Katano, Associate Professor

The Nano-Photoelectronics Laboratory of Prof. Yoichi Uehara and Assoc. Prof. Satoshi Katano conducts research on the physical and chemical phenomena that take place in nanometer-scale regions and their application in optoelectronic devices. In particular, we use a scanning tunneling microscopy (STM) to visualize the individual atoms and molecules. This enables us to reveal the optical responses of the nano materials with atomic-scale precision through the examination of the light emission induced by the injection of tunneling electrons from the STM tip (STM-LE).

The research activities have been carried out with graduate and undergraduate students from the department of electronic engineering, Tohoku University. Currently, one student from China (graduated from Zhejiang University) attends the graduate course to study nanomaterial engineering. Some of our recent achievements are briefly summarized as follows.

1. STM-LE spectroscopy with picosecond time resolution

We have succeeded in the development of a novel surface probing method that can achieve ultimate spatial and temporal resolutions. This has been demonstrated by irradiation of the pulse laser in the STM junction. The laser-induced STM-LE shows a temporal behavior whose duration coincides with the incident laser pulse. The present result opens a new way toward achievement of high-resolution optical spectroscopy in the time, space and energy domains.

2. Vibrational analysis of an individual nanostructure using STM-LE

Identification of the chemical composition of a single molecule is considered to be a central issue for the fabrication of nano-molecular devices. Recently, we have demonstrated that the vibrational excitation of a single molecule can be detected by STM-LE spectroscopy in the visible range. We are also interested in STM-LE measurements in the THz spectral range, which must be utilized as a tool for the direct observation of the vibrational resonance energy.

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