Toward ultimate nonvolatile resistive memories: The mechanism behind ovonic threshold switching revealed

XAS measurements with synchrotron radiation were performed at the BM08/LISA beamline of the European synchrotron (ESRF) thanks to beamtimes under experience numbers 08-01-1037/MA-3993/MA-3995.Computational resources provided by CEA-LETI, the CÉCI funded by the F.R.S.-FNRS under grant number 2.5020.11, and the Tier-1 CWB supercomputer infrastructure (Walloon Region under grant agreement number 1117545).International audienceFifty years after its discovery, the ovonic threshold switching (OTS) phenomenon, a unique nonlinear conductivity behavior observed in some chalcogenide glasses, has been recently the source of a real technological breakthrough in the field of data storage memories. This breakthrough was achieved because of the successful 3D integration of so-called OTS selector devices with innovative phase-change memories, both based on chalcogenide materials. This paves the way for storage class memories as well as neuromorphic circuits. We elucidate the mechanism behind OTS switching by new state-of-the-art materials using electrical, optical, and x-ray absorption experiments, as well as ab initio molecular dynamics simulations. The model explaining the switching mechanism occurring in amorphous OTS materials under electric field involves the metastable formation of newly introduced metavalent bonds. This model opens the way for design of improved OTS materials and for future types of applications such as brain-inspired computing