Electronic Excitation-Induced Semiconductor-Metal Transitions Enabling Ovonic Threshold Switching in Boron Telluride Glasses

Ovonic threshold switching in chalcogenide glasses isa crucialphysical phenomenon behind state-of-the-art memory chip technologies.Binary tellurides are one of the emerging candidates that deliverexcellent properties, notably the large driving current and fast accessingspeed, for volatile selector applications; however, the underlyingswitching mechanism remains poorly understood. To tackle this issue,we targeted the prototypical boron tellurides, further elevating theselector performances. Via ab initio simulating the electronic excitationprocess in the amorphous boron tellurides, we observed reversiblesemiconductor-metal transitions that can reflect the switching principlesof the selectors. The transient switching in conductance originatesfrom fine structural tunings, namely, the changes of constraint surroundingthe big boron clusters and conversions between covalent and hypervalentbonding schemes throughout the entire tellurium network. Our workprovides much-needed atomistic insight into the ovonic threshold switchingmechanisms that may enlighten the material design to enable superiorselector devices.