Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 51: Poster IV

HL 51.31: Poster

Thursday, February 28, 2008, 16:30–19:00, Poster D

I-V - Characteristics of chalcogenide glasses during threshold switching — •Hanno Volker, Carl Schlockermann, Gunnar Bruns, and Matthias Wuttig — 1. Physikalisches Institut 1A, RWTH Aachen, Germany

Phase Change Memories (PCMs) use the contrast in electrical conductivity between the amorphous and the crystalline phase of nanoscale cells of various chalcogenides. This memory technology has very promising scaling properties in contrast to the established flash memories. Switching from the crystalline to the amorphous phase (RESET) is achieved by applying a short, but high, current pulse. This heats the material above the melting temperature. Subsequent rapid quenching creates an amorphous phase. Switching from the amorphous phase to the crystalline phase (SET) is performed by applying a lower, but longer current pulse which heats up the material above the crystallization temperature.

This current can be applied at voltages of the same order of magnitude as for the reset pulse due to an effect called threshold-switching: At a specific threshold voltage, the amorphous material switches from a low-conductive (OFF) state to a high-conductive (ON) state. Several competing models which describe the conduction mechanism in the amorphous state can explain this effect.

Using an extremely fast measurement setup, we have gained a deeper insight both in the life time and I-V properties of this highly non-linear behavioir.