Layer-Switching Mechanisms in Sb2Te3

Interfacial phase-change memory (iPCM) based on layer-structured Ge-Sb-Te crystals has been recently proposed, offering an energy-efficient implementation of nonvolatile memory cells and supplementing the development of Ge-Sb-Te-based phase-change random access memories (PRAMs). Although the working principle of iPCM is still under debate, it is believed that layer-switching plays a role in the switching process between the low-resistance and high-resistance states of iPCM memory cells. However, the role of Ge in forming swapped bilayers-the key elements for layer-switching-is not yet clarified. This work manages to achieve layer-switching in Sb2Te3 thin films by manipulating the formation of bilayer defects using magnetron sputtering and post-thermal annealing. By combining scanning transmission electron microscopy (STEM) experiments with density functional theory (DFT) calculations, the essential role of Sb-Te intermixing is elucidated in stabilizing swapped bilayers at a low energy cost. In situ STEM experiments provide a real-time and real-space view of dynamical reconfiguration of van der Waals-like gaps in Sb2Te3 thin films under electron-beam irradiation. The results show that the Ge atoms are not necessary for the formation and motion of swapped bilayers, providing atomic insights on the layer-switching mechanism in layer-structured binary and ternary group V- and IV-V-tellurides for memory applications.