Internal reverse-biased p-n junctions: a possible origin of the high resistance in phase change superlattice

TL;DR

This paper proposes a simple atomistic transport model suggesting that internal reverse-biased p-n junctions may cause high resistance in phase change superlattices, clarifying the switching mechanism for memory applications.

Contribution

It introduces a unified atomistic model explaining high resistance states in phase change superlattices, challenging previous interpretations of low-resistance states.

Findings

High-resistance state is due to interfacial phase change, not low-resistance phase.

Model aligns with experimental electrical measurements.

Provides new insights into resistance switching mechanisms.

Abstract

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.