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O: Fachverband Oberflächenphysik

O 100: Electronic Structure of Surfaces II

O 100.4: Vortrag

Donnerstag, 19. März 2020, 11:15–11:30, REC C 213

Scanning Tunneling Microscopy of Sub-Surface Atomic Structure of the Phase Change Material GeSb₂Te4 Enabled via Surface Antiresonances — •Philipp Küppers¹, Peter Schmitz², Marcus Liebmann¹, Albert Ratajczak³, Hilde Hardtdegen⁴, Detlev Grützmacher³, Riccardo Mazzarello², and Markus Morgenstern¹ — ¹II. Inst. Phys. B and JARA-FIT, RWTH Aachen University — ²Institut für Theoretische Festkörperphysik, RWTH Aachen University — ³Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI 9) — ⁴Forschungszentrum Jülich GmbH, Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons (ERC-2)

The detailed atomic structure of phase change materials including its disorder is crucial for the understanding of many of its key features. A detailed mapping of the atomic disorder is challenging by standard approaches such as transmission electron microscopy, atom probe tomography or scanning tunneling microscopy. The latter suffers from the fact that the surface is covered by the well ordered Te layer. Here, we show by comparison of scanning tunneling spectroscopy and density functional theory data that details of the subsurface layer consisting of Ge, Sb and vacancies can be mapped by exploiting states that are suppressed towards the surface, so-called surface antiresonances. Probing such states becomes apparent as a honeycomb structure consisting of the Te layer and a significant contribution from the subsurface arrangement.