Project A3:

Scanning tunneling microscopy and angle-resolved photoelectron spectroscopy of phase change materials
(since 2015)

The electronic properties of the prototypical phase change material Ge2Sb2Te5 will be studied in detail within the technologically relevant phases, namely the amorphous and the metastable crystalline one. Photoelectron spectroscopy in combination with magnetotransport will be used to track the development of the Fermi surface and its relation to the conductivity after successive switching events with a special emphasis on the role of the topological surface states. Scanning tunneling spectroscopy will be used to pinpoint subsurface defect configurations and their fate during switching using the recently established time resolution of 120 ps.




Scanning tunneling microscopy and spectroscopy of phase change alloys
(2011 - 2015)

GeSbTe-based phase change alloys are being studied for the first time in ultra high vacuum by scanning tunneling spectroscopy down to temperatures of 4 K. The central aim is to clarify the atomic structure of the amorphous, the metastable crystalline and the stable crystalline phase. The structural properties are being correlated with local electronic properties. Therefore, the established contrast between cations and anions are being extended to the different cations in order to differentiate between Ge, Sb, and vacancies. Atomic arrangements and local binding geometries as, e.g., partially tetraedric Ge-bonds, resonant bonding arrangements or planar vacancy clusters, have to be identified.

Principal investigators:

Prof. Dr. rer. nat. M. Morgenstern
II. Physikalisches Institut B
RWTH Aachen University
Phone: +49 (0)241 80 27075
E-mail: mmorgens@physik.rwth-aachen.de

Dr. rer. nat. M. Liebmann
II. Physikalisches Institut B
RWTH Aachen University
Phone: +49 (0)241 80 27089
E-mail: liebmann@physik.rwth-aachen.de

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