  Phase change superlattice is one of the emerging material technologies for
ultralow-power phase change memories. However, the resistance switching
mechanism of phase change superlattice is still hotly debated. Early electrical
measurements and recent materials characterizations have suggested that the
Kooi phase is very likely to be the as-fabricated low-resistance state. Due to
the difficulty in in-situ characterization at atomic resolution, the structure
of the electrically switched superlattice in its high-resistance state is still
unknown and mainly investigated by theoretical modellings. So far, there has
been no simple model that can unify experimental results obtained from
device-level electrical measurements and atomic-level materials
characterizations. In this work, we carry out atomistic transport modellings of
the phase change superlattice device and propose a simple mechanism accounting
for its high resistance. The modeled high-resistance state is based on the
interfacial phase changed superlattice that has previously been mistaken for
the low-resistance state. This work advances the understanding of phase change
superlattice for emerging memory applications.
