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O: Fachverband Oberflächenphysik

O 47: Electronic Structure of Surfaces: Spectroscopy, Surface States

O 47.8: Poster

Dienstag, 8. März 2016, 18:15–20:30, Poster E

Fermi surface mapping of the phase change material Ge₂Sb₂Te₅ by photoelectron spectroscopy — •Jens Kellner¹, Marcus Liebmann¹, Christian Pauly¹, Jos Boschker², Rui Ning Wang², Evangelos Golias³, Jaime Sanchez-Barriga³, Oliver Rader³, Raffaella Calarco², and Markus Morgenstern¹ — ¹II. Physikalisches Institut B, RWTH Aachen — ²Paul Drude Institut für Festkörpelektronik, Berlin — ³Helmholtz-Zentrum, BESSY, Berlin

Phase change materials (PCM) have become essential components of optical memories (DVD-RW, Blu-ray Disc, ...) and they are important candidates for future non-volatile computer memories. Understanding the fundamental electronic properties would thus be important to improve the phase change characteristics. We present an angle-resolved photoemission (ARPES) study of the ternary PCM Ge₂Sb₂Te₅, epitaxially grown on Si(111) in the metastable cubic phase. The sample was transferred in-situ in ultrahigh vacuum from the molecular beam epitaxy system to the analysis chamber, where we performed a three-dimensional mapping of the band structure by variation of the photon energy (15-31 eV). The states close to the Fermi energy, which are contributing to the transport, are used to construct three-dimensional constant energy surfaces mimicking the Fermi surface relevant for the metallic conductivity of the crystalline phase. Additional spin-polarized ARPES measurements identify a surface state close to the Fermi level with a spin polarization of nearly 100%.