Objectif
In phase change memory devices based on amorphous semiconductor GeSbTe compounds, the switching is achieved through application of current pulses with various pulse widths and trailing edges. When the device is in the low resistance polycrystalline state (set-state) the application of a high amplitude current pulse can increase the local temperature above the melting point and if the trailing edge is short enough the molten state is quenched into an amorphous phase (high resistance-reset state) after the pulse is turned off. Above a threshold dc voltage the amorphous state becomes more conductive, allowing high enough currents to flow and induce spontaneous crystallization due to joule heating. This way the device switches back to its low resistance-set state. In this project the stability of the switching parameters (threshold voltage and reset resistance) in time will be studied using radio frequency (RF) probes and a time domain sampling oscilloscope. Performed measurements on the already fabricated samples of Ge2Sb2Te5 nanopillars with circular or rectangular cross-sections down to 50 nm in diameter will elucidate the role of nano-scale current distribution in the overall drift characteristics. Further measurements at elevated temperatures will reveal the relative contributions from thermally accelerated structural relaxations and electronic relaxation mechanisms. In our study, we will gain a much better understanding of the nature of the drift properties of the switching parameters and therefore we will contribute to the solution and control of one of the most important problems in the practical applications of phase change memory, one of the most important memory devices that nanotechnology has produced as of today.
Champ scientifique
Appel à propositions
FP7-PEOPLE-2009-RG
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Régime de financement
MC-IRG - International Re-integration Grants (IRG)Coordinateur
34342 Istanbul
Turquie