In-situ observation of Ge₂Sb₂Te₅ crystallization at the passivated interface

The unique properties of phase change materials (PCMs) in the amorphous and crystalline phase, and the feasibility of manipulating the phase transition process, have enabled the application of PCMs in optics and electronics systems, for data storage and neuromorphic computing. As the semiconductor device employing PCMs scales down with the complementary metal oxide semiconductor (CMOS) technology node, the impact of interface on the crystallization of PCMs becomes increasingly significant, that is of great importance for the system performance, e.g. phase change memory (PCM). In this work, crystallization of Ge₂Sb₂Te₅ (GST) on passivated SiO₂ surface is triggered by thermal pulses, in-situ observed in transmission electron microscope. A distinguishing heterogenous nucleation dominated crystallization behavior of GST has been verified at the GST/SiO₂ interface. Meanwhile, in the in-situ prepared reactive GST/SiO₂ interface, the interfacial covalent interaction between atoms in GST and SiO₂ is believed to hamper the GST nucleation at the interface. Interfaces consist of the same materials but with different reactivity will lead to distinct crystallization behaviors of PCMs. By forming passive interface between PCMs and surrounding dielectric materials, promotion in nucleation and enhancement in operation speed can be expected in PCM with decreasing cell size.