  Interfacial Phase Change Memory (iPCM) retrench unnecessary power consumption
due to wasted heat generated during phase change by reducing unnecessary
entropic loss. In this study, an advanced iPCM (GeTe/Ti-Sb2Te3 Superlattice) is
synthesized by doping Ti into Sb2Te3. Structural analysis and density
functional theory (DFT) calculations confirm that bonding distortion and
structurally well-confined layers contribute to improve phase change properties
in iPCM. Ti-Sb2Te3 acts as an effective thermal barrier to localize the
generated heat inside active region, which leads to reduction of switching
energy. Since Ge-Te bonds adjacent to short and strong Ti-Te bonds are more
elongated than the bonds near Sb-Te, it is easier for Ge atoms to break the
bond with Te due to strengthened Peierls distortions (Rlong/Rshort) during
phase change process. Properties of advanced iPCM (cycling endurance, write
speed/energy) exceed previous records. Moreover, well-confined multi-level
states are obtained with advanced iPCM, showing potential as a neuromorphic
memory. Our work paves the way for designing superlattice based PCM by
controlling confinement layers.
