Direct Measurement of Trap Spacing in Phase Change Memory Cells Using ATE Devices

The electrical conduction in the amorphous state of the phase change material is through the localized states. The density of these trap states or the trap spacing plays a major role in determining the characteristics of the PCM cell in the sub threshold region. In this work, we have developed a method to extract the trap spacing in the amorphous material directly from the I-V characteristics rather than the conventional method of curve fitting. Further the dependence of the trap spacing on the amorphous thickness and reset voltage is discussed. Preliminary results on the 1/f noise measurements are also reported.