Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 66: Electronic Structure of Surfaces
O 66.11: Poster
Mittwoch, 18. März 2015, 18:15–21:00, Poster A
Low temperature scanning tunneling microscopy investigation of the phase change material Ge2Sb2Te5 — •Jens Kellner1, Christian Pauly1, Marcus Liebmann1, Jos Boschker2, Volker Deringer3, Raffaella Calarco2, Richard Dronskowski3, and Markus Morgenstern1 — 1II. Physikalisches Institut B, RWTH Aachen University and JARA-FIT, Germany — 2Paul Drude Institut für Festkörpelektronik, Berlin, Germany — 3Institute of Inorganic Chemistry, RWTH Aachen University, Germany
We present a scanning tunneling microscopy (STM) study of the phase change material GST-225 (GST), epitaxially grown on Si(111) in the metastable cubic phase, transferred in-situ in ultrahigh vacuum from the molecular beam epitaxy system to the STM. Despite the fact that GST is already commercially used, there is still no complete understanding of the ultra fast switching speed, the strong resistance change and the high endurance of the Ge-Sb-Te alloys. One contribution to such a theory is an atomic scale understanding of the electronic properties of GST. V. Deringer modeled the surfaces by cutting slabs from the hexagonal bulk cells of GST followed by relaxation. The relaxed structure features a number of octahedral and tetrahedral Ge bonds which can be distinguished in the density of states (DOS) projections. We detected the differential conductivity of such states by scanning tunneling spectroscopy at 0.4 K leading to an identification of different bonding configurations.