The "gene" of reversible phase transformation of phase change materials: Octahedral motif

Nonvolatile phase change random access memory (PCRAM) is regarded as one of promising candidates for next-generation memory in the era of Big Data. The phase transition mechanism of phase change materials is the key scientific issue to be addressed for phase change memory. Moreover, obtaining homogeneous phase change materials with high speed, low power consumption, long life and good thermal stability is still the ultimate challenge for high-density three-dimensional (3D) PCRAM. In this paper, starting from the octahedral structure motifs (octahedrons) which are considered as the "gene" of phase change materials, a new view on the phase transition mechanism is proposed. Based on this mechanism, a homogeneous phase change material is developed by constructing three matched octahedrons, which achieved an overall improvement in performance, showing 180 ℃ ten-year data retention, 6 ns SET speed, one order of magnitude longer life time and 75% reduced power consumption compared with traditional Ge₂Sb₂Te₅ (GST) devices. It is of great significance to use it in 3D PCRAM chip and multi-level brain- inspired computing chip in the future.