Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.17: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Scanning tunneling microscopy and spectroscopy of the phase change alloy Ge₂Sb₂Te₅ — •Jens Kellner¹, Christian Pauly¹, Marcus Liebmann¹, Alessandro Giussani², Raffaella Calarco², and Markus Morgenstern¹ — ¹II. Phys. Inst. B, RWTH Aachen University and JARA-FIT, Germany — ²Paul Drude Institut für Festkörperelektronik, Berlin, Germany

We use scanning tunneling microscopy (STM) in ultrahigh vacuum (UHV) to probe the local atomic structure and the electronic properties of the phase change alloy Ge₂Sb₂Te₅(0001) grown on Si(111) by molecular beam epitaxy. In order to obtain a clean surface, the mixed native oxides on the GST surface were removed by dipping the sample in de-ionized water followed by annealing at 200^∘C in UHV [1]. We realized images with atomic resolution in constant-current mode at different voltages in order to distinguish different chemical elements on the surface. Local variations in the atomic corrugation and lattice constants are found and analyzed in detail. Using the spectroscopy mode, we find a band gap of about 500 meV. A p-type doping becomes apparent in agreement with photoelectron spectroscopy data.

[1] Z. Zhang et al., Appl. Surf. Sci. 256, 7696 (2010).