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

Ovonic threshold switching in chalcogenide glasses is a crucial physical phenomenon behind state-of-the-art memory chip technologies. Binary tellurides are one of the emerging candidates that deliver excellent properties, notably the large driving current and fast accessing speed, for volatile selector applications; however, the underlying switching mechanism remains poorly understood. To tackle this issue, we targeted the prototypical boron tellurides, further elevating the selector performances. Via ab initio simulating the electronic excitation process in the amorphous boron tellurides, we observed reversible semiconductor-metal transitions that can reflect the switching principles of the selectors. The transient switching in conductance originates from fine structural tunings, namely, the changes of constraint surrounding the big boron clusters and conversions between covalent and hypervalent bonding schemes throughout the entire tellurium network. Our work provides much-needed atomistic insight into the ovonic threshold switching mechanisms that may enlighten the material design to enable superior selector devices.