Investigation of Trap Spacing for the Amorphous State of Phase-Change Memory Devices

The subthreshold conduction in the amorphous state of the phase-change material is dominated by the hopping of the carriers through the trap states or localized states with the assistance of the electric field across the material. It is important to understand the nature and number of these traps to properly model the physics of the conduction, threshold switching, and drift in phase-change materials. In this paper, we present a device structure and a methodology to extract the trap spacing directly from the I-V characteristics of the device. Furthermore, the dependence of the trap spacing on the amorphous region thickness, reset voltage, and drift is also discussed. These results are then correlated with the 1/f noise measurements of the device.