Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 90: Phase change / resistive switching (DS with HL)

HL 90.3: Talk

Thursday, March 19, 2015, 15:30–15:45, H 0111

Epitaxial and textured Ge-Sb-Te phase-change thin films investigated by Cs-corrected STEM — •Ulrich Roß, Andriy Lotnyk, Erik Thelander, and Bernd Rauschenbach — Leibniz-Institut für Oberflächenmodifizierung e.V. Permoserstr. 15 D-04318 Leipzig

Chalcogenide phase change compounds are under intense scrutiny for emerging data storage and fast switching electronic memory applications. The unique properties of this class of materials are based on the distinct change in electrical conduction and optical reflectivity upon transition between crystalline and amorphous states. Much interest has been focused on compounds from the stoichiometric tie-line (GeTe)_x-(Sb₂Te₃)_1−x in the Ge-Sb-Te intermetallic system. For the development of phase change memory in particular, oriented, epitaxial and layered thin films have been reported to display significantly enhanced switching properties.

We have performed a detailed high-resolution scanning transmission electron microscopy (STEM) investigation of fast grown Ge₂Sb₂Te₅ thin films on native amorphous silicon oxide as well as oriented BaF₂(111) and Si(111) substrates, produced by pulsed laser deposition. Formation of the crystalline phases was induced by deposition at elevated temperatures as well as post-deposition heat treatment. An analytical probe aberration-corrected FEI Titan³ G2 60-300 S/TEM was used in order to correlate treatment conditions and local structure at the atomic scale. The interplay between grain texture, lattice disorder and local composition variations will be discussed.