Berlin 2018 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 17: Focussed Session: Atomic Scale Characterization

HL 17.6: Hauptvortrag

Dienstag, 13. März 2018, 11:30–12:00, EW 202

Modulating electron beams in space and time to probe for genuine structures and function at the atomic scale — •Christian Kisielowski — Lawrence Berkeley National Laboratory

n high resolution electron microscopy objects are actively altered by the intense electron irradiation that is necessary to reach single atom sensitivity. In these circumstances a control of beam-sample interactions is no longer a commodity but a necessity. Therefore, it is of outstanding interest to develop new tools and concepts that strive for a stricter control of the probing electron beam in space and time in order to optimize the detection of every scattering event.

This contribution describes research that aims at exploiting the emerging ability to better understand layered semiconductors and other nano-materials containing soft and hard matter components by directly determining their atom arrangement in three-dimensions using low-dose rate electron microscopy. The approach mimics best practices in biological research by capturing series of entirely noise dominated images with dose rates that can be smaller than 20 e/Å2s, which are successively reconstructed to obtain in-line holograms with unprecedented contrast and resolution.

In such images we observe a variety of previously unknown atom configurations that are otherwise hidden behind a barrier of beam-induced object alterations and capture radiation sensitive structures at atomic resolution even if they are greatly affected by an exposure of the material to water vapor or other gases. Recent progress with time resolved electron microscopy further accelerates the progress.