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 GeTe 6 (floppy) devices belonging to the binary Ge x Te 100- x glass system. Time-resolved electrical measurements were performed on the as-deposited amorphous GeTe and GeTe 6 -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 ( V T ) and require more than 70% overvoltage above V T to reduce the delay time to an order lower value. In contrast, GeTe 6 devices switch significantly faster within a relatively shorter delay time of ∼2.6 ns at V T and the delay time reduced to ∼800 ps within a minimal overvoltage of 26% above V T . The voltage-dependent delay time characteristics validate a significantly sharper exponential reduction in the delay time for GeTe 6 compared to GeTe devices. Confocal Raman spectroscopic measurements were carried out on GeTe and GeTe 6 thin films, validating the role of Te–Te network connectivity in shaping the vibrational landscape and rigidity of the amorphous Ge x Te 100- x glass systems. Together, these findings corroborate the floppy (GeTe 6 ) network that possesses longer Te–Te linkages, promoting higher transient phonon interactions and governing subnanosecond TS for a lower applied voltage above V T . 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 (GeTe 6 ) and PCM (GeTe) devices.