Impact of Te Network Connectivity in Governing the Threshold Switching Dynamics of Amorphous GeTe and GeTe ₆ Devices

The threshold switching (TS) in amorphous chalcogenides is a critical factor governing the performance of phase-change memory (PCM) and Ovonic Threshold Switching (OTS) selector devices. While its technological relevance is well-established, the dynamics of resistance breakdown during TS, especially its relationship to the atomic-scale network, remains unclear. In this study, we investigate the influence of amorphous network connectivity and rigidity percolation on the TS dynamics of GeTe (rigid) and GeTe6 (floppy) devices belonging to the binary GexTe100-x glass system. Time-resolved electrical measurements were performed on the as-deposited amorphous GeTe and GeTe6-based devices to precisely capture the current evolution from subthreshold to superthreshold regimes. GeTe devices exhibit a relatively longer delay time of ∼14 ns at the threshold voltage (VT) and require more than 70% overvoltage above VT to reduce the delay time to an order lower value. In contrast, GeTe6 devices switch significantly faster within a relatively shorter delay time of ∼2.6 ns at VT and the delay time reduced to ∼800 ps within a minimal overvoltage of 26% above VT. The voltage-dependent delay time characteristics validate a significantly sharper exponential reduction in the delay time for GeTe6 compared to GeTe devices. Confocal Raman spectroscopic measurements were carried out on GeTe and GeTe6 thin films, validating the role of Te–Te network connectivity in shaping the vibrational landscape and rigidity of the amorphous GexTe100-x glass systems. Together, these findings corroborate the floppy (GeTe6) network that possesses longer Te–Te linkages, promoting higher transient phonon interactions and governing subnanosecond TS for a lower applied voltage above VT. On the other hand, rigid (GeTe) networks dominated by Ge–Te bonding with damped Te–Te vibrational modes exhibit a delayed TS process. These results elucidate the influence of the network connectivity and its impact on local phonons in enabling extraordinarily faster TS in chalcogenide-based OTS selectors (GeTe6) and PCM (GeTe) devices.