Scanning Tunneling Spectroscopy


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A scanning tunneling microscope (STM) is based on the concept of quantum tunneling. When a conducting tip is approached to the sample within a nanometer size, tunneling current starts to flow quantum mechanically. The tunneling current depends on the tip position, applied voltages, and the local density of states (LDOS). Information of the tip position constitutes the topographic image with a feedback process. The local variations of LDOS shows the quantum fluctuation of the energy states.
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An example of topographic images measured on a topological insulator (see Research tap for details), Bismuth Telluride. Fe single atoms are deposited on the surface by thermal evaporation (bright spots in the image). This image is taken during my postdoc in Princeton University.
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Specra measured on different postions of the tip. The variation of the spectra shows that the LDOS is modified due to the many body effect including electron-electron interactions. This spatial variation consitutes the map of LDOS fluctuations.

Contact

Jungpil Seo (DGIST, Assistant Professor)
Dept. of Emerging Materials Science
Email: jseo-at-dgist.ac.kr

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