Synergistic Breakthrough in Speed and Power: TiO₂/SiO₂ Stacked Dielectric Heterostructures for Phase-Change Memory

Phase-change memory (PCM) emerges as a leading contender for storage-class memory applications yet faces inherent trade-offs between SET speed and RESET power due to competing crystallization and melt-quench dynamics. Herein, we demonstrate a stacked dielectric heterostructure strategy integrating lattice-matched TiO₂ and thermal-confining SiO₂ interlayers to overcome these limitations. The crystalline TiO₂ layer lowers nucleation barriers via epitaxial matching, while the ultralow thermal conductivity SiO₂ layer confines Joule heating localization via thermal-field regulation. By optimizing interlayer thicknesses guided by Poole-Frenkel emission modeling and interface state density analysis, the stacked dielectric PCM device achieves synchronized breakthroughs: 8 ns ultrafast speed (meeting DRAM-grade speed) and 2 pJ ultralow energy consumption. Finally, the localized thermal confinement capability of SiO₂ induced by Joule heating and the crystallographic plane matching of TiO₂ have been corroborated through finite element simulations and TEM characterization. This work further advances the development of PCM for high-speed cache memory applications.