Concepedia

Energy-Efficient Phase-Change Memory with Graphene as a Thermal Barrier

Chiyui Ahn, Scott W. Fong, Yongsung Kim, Seunghyun Lee, Aditya Sood, Christopher M. Neumann, Mehdi Asheghi, Kenneth E. Goodson, Eric Pop, H.‐S. Philip Wong

Nano Letters · 2015 · 142 citations · 35 references

DOI

TL;DR

Phase‑change memory (PCM) is an important class of data storage, yet lowering the programming current of individual devices remains a significant challenge. The study aims to improve PCM energy‑efficiency by adding a graphene layer at the interface between the phase‑change material Ge₂Sb₂Te₅ (GST) and the bottom electrode heater. This is accomplished by inserting graphene between GST and the tungsten electrode, creating an interfacial thermal barrier that confines heat within the active volume. The resulting G‑PCM devices show about 40 % lower RESET current, sustain 105 programming cycles, and the added thermal resistance may enhance endurance by limiting atomic migration at the interface.

Abstract

Phase-change memory (PCM) is an important class of data storage, yet lowering the programming current of individual devices is known to be a significant challenge. Here we improve the energy-efficiency of PCM by placing a graphene layer at the interface between the phase-change material, Ge2Sb2Te5 (GST), and the bottom electrode (W) heater. Graphene-PCM (G-PCM) devices have ∼40% lower RESET current compared to control devices without the graphene. This is attributed to the graphene as an added interfacial thermal resistance which helps confine the generated heat inside the active PCM volume. The G-PCM achieves programming up to 105 cycles, and the graphene could further enhance the PCM endurance by limiting atomic migration or material segregation at the bottom electrode interface.