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DS: Fachverband Dünne Schichten

DS 39: Focus Session: Resistive Switching by Redox and Phase Change Phenomena VI (Kinetics and Transport in PC materials)

DS 39.4: Talk

Thursday, April 3, 2014, 10:30–10:45, CHE 89

Drift of the voltage dependence of resistance in melt-quenched phase change memory cells — •Martin Wimmer, Matthias Kaes, and Martin Salinga — 1. Physikalisches Institut (IA), RWTH Aachen

Phase change materials are the essential ingredients for promising novel non-volatile electronic memory devices. The materials have the ability to be switched upon electrical excitations within nanoseconds between two otherwise stable phases, which show large contrast in electrical resistivity. One approach to improve the information density of such a phase change memory device is to store several logic bits in one physical cell by distinguishing between different states of partial crystallization (multilevel storage). For such a device it is important that the resistance is stable over many orders of magnitude in time. While for the crystalline phase this requirement is sufficiently fulfilled, the amorphous phase shows a strong time dependence of the resistance, the so-called resistance drift. In literature this effect is often ascribed to structural relaxation effects, which, as a consequence, lead to changes of electronic defect states and thereby altering the electronic properties, e.g. the conductivity, of the material. In this work, we study the effect of drift on the voltage dependence of the resistance in phase change memory devices on a time scale starting only microseconds after melt-quenching. Our experimental findings are interpreted within the common drift theories, e.g. the Poole-Frenkel model for conduction in the sub-threshold regime.