Threshold and Filament Current Densities in Chalcogenide-Based Switches and Phase-Change-Memory Devices

Threshold current density of switching was found to grow several decades at constant threshold electric field with reducing interelectrode distance. Data are compared with predictions of various switching theories. Experimental estimate of current density in an electronic filament is reported based on a programming "dead-space" observation in a ring contact device with one subcritical bottom contact dimension. Significance of the shape of S-type negative differential conductivity curve and, namely, the slope of the second part with positive differential conductivity for the programming of phase-change memory is discussed.