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DS: Fachverband Dünne Schichten

DS 44: Poster III: Focus session: Resistive switching by redox and phase change phenomena

DS 44.18: Poster

Donnerstag, 3. April 2014, 16:00–19:00, P1

An alternative route for crossing the metal-insulator transition in GeTe-Sb₂Te₃-alloys — •Annika Poitz, Hanno Volker, Peter Jost, Peter Zalden, Tobias Schäfer, and Matthias Wuttig — I. Physikalisches Institut (IA), RWTH Aachen, 52056 Aachen

Phase-change materials (PCMs) are outstanding materials: Besides a fast transition between the amorphous and the crystalline state, these materials show a high contrast in their optical and electrical properties. Due to these properties PCMs can be employed in optical and electrical memory technologies.

Recently it has been demonstrated^[1] that the resistivity in the crystalline phase in some PCMs such as Ge₁Sb₂Te₄ depends on the annealing temperature. Higher annealing temperatures lead to smaller resistivities and even a change from non-metallic to metallic behavior. This is explained by a reduction of disorder upon annealing, which leads to a disorder-driven metal-insulator transition (MIT). This MIT has been proven to be independent of structural transitions^[1]. However Ge₁Sb₂Te₄ shows a cubic to trigonal transition near the MIT, which hampers a clear distinction between the influences of disorder and crystalline structure.

In this study we report an MIT in PCMs without such a structural change. Instead of annealing, we control disorder by varying the stoichiometry of (Sb₂Te₃)_1-x(GeTe)_x-alloys with 0.75≤ x ≤ 1. In this study we employ low- and high-temperature resistivity, Hall-effect and XRD measurements for a characterization of the samples.

^[1] T. Siegrist et al., Nat. Mat. 10, 202 (2011)