The GroupAction PhotosNano Group Alumni
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We develop and apply low-temperature scanning probe techniques to study the behavior of charges in nanoscale systems. The techniques include Scanning Tunneling Microscopy and Charge Imaging -- a novel low temperature probe of electron accumulation. The method achieves an incredible sensitivity of 0.01 electrons per root hertz. Current projects include probing electrons in atomic-scale semiconductor structures, metallic systems, and biological nanowires. |
| The schematic picture above shows a recent experiment,
published in Nature Physics,
which detected individual electrons entering small clusters of donor atoms below the surface of a
gallium-arsenide semiconductor. The schematic shows a gray metallic tip positioned above two closely-spaced donor atoms.
If the atoms are close together compared to their effective Bohr radius (a few nanometers), the stong interaction alters the quantum
structure of electrons trapped on the donors. The effective trapping-potential wells are shown in dark red. In this way, the study
demonstrated that we can probe the smallest possible semiconductor devices -- composed of one or more individual dopant atoms.
The research described on this site was funded by grants from the National Science Foundation (DMR-0906939), the MSU Institute for Quantum Sciences, the MSU Foundation (Strategic Partnership Grant), and the Alfred P. Sloan Foundation. |
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The background pattern is an artist's view of atomic-scale three-leaved clovers -- formed by the electronic structure of selenium atoms on the surface of Bi2Se3, a narrow-gap semiconductor (paper). The pattern results from the interaction between the surface and a subsurface substitutional defect. The study was carried out by Tessmer's first grad student (now professor), Sergei Urazhdin. |  |