Understanding the role of GeSbTe layer on atomic switch through current sweep mode measurement for enhanced threshold switching device

We demonstrate how to improve the turn-off speed of Ag-based volatile atomic switches with an Al2O3 electrolyte by understanding the origin of filament instability. Under the current sweep mode, our findings reveal that the formation of Ag–Te bonding due to the insertion of a GeSbTe layer (Ag/GeSbTe/Al2O3-based device) prevents the formation of a thick and stable Ag filament. As a result, the end of the filament appears to have the size of a single Ag atom, when analyzed based on the quantum conductance model. Thus, the instability of the Ag filament is maximized because of the large surface energy of the small filament. Furthermore, the low thermal conductivity of GeSbTe maximizes the internal thermal energy and accelerates the spontaneous dissolution of the unstable Ag filament. Based on these observations, the GeSbTe layer was introduced into the Ag/HfO2-based volatile atomic switch to quantify its effects on the turn-off speed. Our results show that the turn-off speed can be increased by more than a hundredfold by controlling both the amount of metal ions in the electrolyte and the internal thermal energy.