$\hbox {Ge}_{2}\hbox {Sb}_{2}\hbox {Te}_{5}$ as a Ferroelectric: A Single-Element Low-Voltage Dynamic Memory

Ge₂Sb₂Te₅ (GST) is normally employed as a current-driven and heat-triggered structural phase-change material in multielement phase-change memories. This work identifies GST as a ferroelectric material suitable for a single-element memory operating at low voltages without heat-based transformation. With GST as a floating gate, hysteretic behavior that is opposite of that arising from charge trapping and consistent with ferroelectric phase transition is characterized. Saturating memory window of ~1 V under ±4 V cycling and retention times of hundreds of seconds constrained by depolarization are observed. Extracted remnant polarization is ~0.13 μC/cm². The result suggests potential for embedded use with the advantages of a retention time that is competitive or better than DRAMs, a single-element transistorlike structure and technologically easy integration.