Transition from junction limited to bulk limited subthreshold conduction in phase change memory

The impact of junction formed by the electrode and bulk in phase change memory to conduction at the amorphous high resistance state is studied in this paper. Analytical model deduced from basic physical equation elucidates that the current changes from junction barrier limited to bulk barrier limited when the applied voltage increases. The currents deduced from the model are in highly consistent with the measurement data at different temperatures. It is also found that the junction barrier becomes non-negligible when the radius of bottom electrode is scaled down to 20 nm.