Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 27: Thin film characterization: structure analysis and composition (post growth analysis XRD, etc..)
DS 27.1: Vortrag
Mittwoch, 28. März 2012, 16:30–16:45, H 2032
Molecular beam epitaxy of Ge-Sb-Te thin films on Si substrates — •Alessandro Giussani1, Perumal Karthick1, Peter Rodenbach1, Michael Hanke1, Wolfgang Braun1,2, Raffaella Calarco1, and Henning Riechert1 — 1Paul Drude Institut für Festkörpelektronik, Hausvogteiplatz 5-7, 10117 Berlin — 2CreaTec Fischer Co. GmbH, Industriestr. 9,74391 Erligheim, Germany
Owing to their phase-change properties, Ge-Sb-Te thin films, i.e., Ge2Sb2Te5 (GST), are being intensively studied for new concepts of non-volatile memory. The deposition technique commonly employed is sputtering, leading to poly-crystalline layers. Here it is shown that molecular beam epitaxy allows for the preparation of highly ordered Ge-Sb-Te films even on strongly lattice-mismatched substrates like Si. In situ reflection high-energy diffraction and quadrupole mass spectrometry are utilized to monitor the growth process in real time. Ex situ x-ray diffraction, atomic force microscopy and secondary electron microscopy, and x-ray fluorescence are used to investigate the structural properties, the surface morphology, and the stoichiometry of the grown films, respectively. As main result, single crystalline GST layers can be achieved on Si(111) substrates with epitaxial relationships GST[111]//Si[111] and GST<-110>//Si<1-10> in the growth direction and in-plane, respectively. The growth on Si(001) instead produces (111)-oriented films with weak texture. GST thin films with a high structural order are expected to exhibit superior electrical/switching properties to the poly-crystalline layers deposited by sputtering.