Dresden 2011 – scientific programme

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DS: Fachverband Dünne Schichten

DS 42: Poster I: Progress in Micro- and Nanopatterning: Techniques and Applications (jointly with O); Spins in Organic Materials; Ion Interactions with Nano Scale Materials; Organic Electronics and Photovoltaics; Plasmonics and Nanophotonics (jointly with HL and O); High-k and Low-k Dielectrics (jointly with DF); Organic Thin Films; Nanoengineered Thin Films; Layer Deposition Processes; Layer Properties: Electrical, Optical, and Mechanical Properties; Thin Film Characterisation: Structure Analysis and Composition; Application of Thin Films

DS 42.93: Poster

Wednesday, March 16, 2011, 15:00–17:30, P1

Trends in crystallization behavior of phase-change materials under high external pressure — •Matthias Kaes¹, Peter Zalden¹, Julia van Eijk¹, Giuliana Aquilanti², Sakura Pascarelli², and Matthias Wuttig¹ — ¹I. Physikalisches Institut (1A), RWTH Aachen University, D-52056 Aachen, Germany — ²European Synchrotron Radiation Facility, Grenoble, France

Phase-change materials (PCMs) exhibit a rapid crystallization of their amorphous phase and a related change in electrical conductivity of several orders of magnitude. There have been estimations that high pressures (6 GPa) might occur in a phase-change random access memory (PCRAM)-cell due to thermal expansion, which could influence the switching mechanism in small PCRAM-cells. Moreover, PCMs show surprising pressure-dependent behavior, as the prototypical PCM Ge₂Sb₂Te₅ has been observed to amorphize under increasing pressures (10-20 GPa) [1].

Here, we present in-situ EXAFS experiments at the Ge K absorption edge by which we have investigated the pressure-induced changes in short-range order in Ge₂Sb₂Te₅ and Ge₄Sb₁Te₅.

While both materials show similar crystallization behavior under ambient pressure, it is found that the crystallization is influenced or even suppressed by applied external pressures. We compare our results with previous findings and derive stoichiometric trends, from which we propose that the reliability of PCRAM-devices could benefit from the use of PCMs with high content of GeTe.

[1] A.V. Kolobov et al. Physical Review Letters 035701, p. 2-5 (2006).