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DS: Fachverband Dünne Schichten

DS 44: Postersession II

DS 44.29: Poster

Donnerstag, 23. März 2017, 17:00–19:00, P1C

Influence of Microstructure on the Amorphous to Crystalline Phase Transition in the Phase-Change Material GST124 — •Carl-Friedrich Schön, Nikita Polin, Matthias M. Dück, Christoph Persch, and Matthias Wuttig — I. Physikalisches Institut (IA), RWTH Aachen University, D-52056 Aachen, Germany

Phase-change materials (PCM) are a promising candidate for universal memory, as their optical reflectivity and electrical resistivity change considerably along the nanosecond scale transition between the amorphous and the crystalline state. Because this phase transition is the foundation of device functionality, significant effort has been devoted to its understanding. The microstructure of PCM thin films has been found to heavily impact the properties of the phase transition in GST124. While the investigation of microstructural defects is not relevant for application, it might yield new insights into the fundamental mechanisms of the phase transition.

In this work, the microstructure of GST124 thin films is varied and characterized utilizing x-ray reflectivity (XRR) and scanning electron microscopy (SEM). The effects of the microstructure on the film's properties are then measured by x-ray diffraction (XRD), while the phase transition is investigated with a laser setup featuring a high and low power laser combination, enabling the measurement of the materials reflectivity during crystallization. A higher gas pressure causes an increased incorporation of voids as well as an increased minimum energy to crystallize the sample. This energy shift can be attributed to the change of microstructure, as subsidiary effects can be excluded.