Regensburg 2019 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 36: Liquid and Amorphous Metals

MM 36.2: Talk

Thursday, April 4, 2019, 10:30–10:45, H46

Impact of Glass Transition on Crystallization Kinetics of Phase-Change Material Ge2Sb2Te5 — •Julian Pries¹, Shuai Wei¹, Matthias Wuttig^{1, 2}, and Pierre Lucas³ — ¹Institute of Physics IA, RWTH Aachen University, Germany — ²Peter Grünberg Institute (PGI 10), Forschungszentrum Jülich, Germany — ³Department of Materials Science and Engineering, University of Arizona, United States

Phase-Change materials (PCMs) can be switched in nanoseconds between the amorphous and crystalline phase. In combination with the pronounced change of physical properties like electrical resistivity or optical reflectivity upon this transition, PCMs offer a wide potential for memory applications. A deep understanding of crystallization kinetics is essential for increasing the data transfer rate of such devices. Here, crystallization kinetics of the prototypical PCM Ge2Sb2Te5 is investigated. Combining conventional and Flash DSC opens a heating rate interval of over six orders of magnitude. The resulting crystallization data reveals a sharp transition from a high to a low Kissinger activation energy of crystallization when exceeding the critical heating rate. Moreover, pre-annealing affects this activation energy at low, but not at high rates. Utilizing Fluctuation Electron Microscopy and JMAK-simulations uncovers the origin of this behavior: The manifestation of glass dynamics and glass transition in crystallization behavior. Accordingly, Ge2Sb2Te5 crystallizes from the glass at low and undercooled liquid phase at high heating rates. The presence of this transition has major consequences for estimating the performance of PCM memory.