A Unified Hopping Model for Subthreshold Current of Phase-Change Memories in Amorphous State

The conduction process of phase-change-memory (PCM) devices in the amorphous high-resistance state is described by a trap-limited transport model. Based on numerical simulations of the barrier lowering in a potential landscape due to localized charged states, we propose a physically based analytical hopping model accounting for the different voltage dependence of current characteristics in the low- and high-field regimes. The analytical model is able to accurately describe, with the same set of parameters, the experimental behavior of both the temperature-dependent I- V curves and the voltage-dependent activation energy for conduction. Comparison with experimental data is provided, demonstrating the physical consistency of the proposed model.