Concepedia

Breaking the Speed Limits of Phase-Change Memory

Desmond K. Loke, T. H. Lee, W. J. Wang, Lu Shi, Rong Zhao, Yee‐Chia Yeo, Tow Chong Chong, Stephen R. Elliott

Science · 2012 · 835 citations · 33 references

TL;DR

Phase‑change random‑access memory (PCRAM) is a leading candidate for next‑generation data‑storage, yet its performance is limited by a trade‑off between crystallization speed and amorphous‑phase stability. The study seeks to control PCRAM crystallization kinetics by applying a constant low voltage through prestructural ordering (incubation) effects. This control is achieved by a constant low‑voltage, prestructural‑ordering protocol, supported by ab initio molecular‑dynamics simulations that reveal the kinetics and structural basis of the incubation‑assisted speed increase. The method achieves a 500‑picosecond crystallization speed with reversible switching, enabling nonvolatile operation beyond gigahertz data‑transfer rates.

Abstract

Phase-change random-access memory (PCRAM) is one of the leading candidates for next-generation data-storage devices, but the trade-off between crystallization (writing) speed and amorphous-phase stability (data retention) presents a key challenge. We control the crystallization kinetics of a phase-change material by applying a constant low voltage via prestructural ordering (incubation) effects. A crystallization speed of 500 picoseconds was achieved, as well as high-speed reversible switching using 500-picosecond pulses. Ab initio molecular dynamics simulations reveal the phase-change kinetics in PCRAM devices and the structural origin of the incubation-assisted increase in crystallization speed. This paves the way for achieving a broadly applicable memory device, capable of nonvolatile operations beyond gigahertz data-transfer rates.