Berlin 2015 – wissenschaftliches Programm
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MI: Fachverband Mikrosonden
MI 2: Analytical Transmission Electron Microscopy and Atom Probe Tomography
MI 2.2: Vortrag
Montag, 16. März 2015, 12:15–12:30, EMH 225
In-situ Transmission Electron Microscopy Study of Ge(8- n)Sn(n)Sb2Te11 — Dietrich Häußler1, •Torben Dankwort1, Lorenz Kienle1, Christine Koch2, Wolfgang Bensch2, and David C. Johnson3 — 1Institut für Materialwissenschaft, CAU Kiel — 2Institut für Anorganische Chemie, CAU Kiel — 3University of Oregon, Eugene, USA
(GeTe)x(Sb2Te3)y - known as phase change materials (PCM) - are of large interest for applications in data storage devises like blu-ray discs. We report on a novel type of short range ordering phenomena for Ge(8-n)Sn(n)Sb2Te11 (n=2, n=4). Amorphous, stoichiometric thin films of such compositions and with thicknesses <40 nm were directly deposited on carbon coated Ni grids using molecular beam epitaxy. In-situ heating TEM experiments revealed an exceptional growth of large grains with sizes >500 nm starting at 130°C. Furthermore, diffuse scattering was observed in electron diffraction patterns, which implies short range order phenomena unknown for PCMs so far. In-situ heating experiments indicate that close to 150°C diffuse scattering is altered to an ordered superlattice structure. This is in accordance with the resistance-temperature behavior, which is characterized by a remarkable additional resistance drop at ~150°C (heating rate of 5 K/min). Possibly, these results suggest that the diffuse scattering is an indication for a new intermediate phase.