Abstract
Phase coexistence in nanoscale electrochemical random-access memory (ECRAM) has recently been demonstrated to enable both information storage and extraordinary reconfigurability. These proof-of-principle demonstrations have left the mechanistic details of such a process unresolved. Particularly, the mechanisms that stabilize the multiple phases, and the underlying processes behind sustained memory retention, remain unclear, and are necessary to design such devices. Here we report microscale ECRAM devices composed of VOx, which enables us to directly probe the active region in an operando fashion using optical techniques. Using Raman mapping, we show the phase coexistence driven by the electrochemical injection of O vacancies to be spatially uniform (i.e., with no filaments). The stability was observed to be unusually long, with 1% loss over 14 years in ambient conditions. First-principles calculations of the oxygen vacancy formation energies in VOx further support the thermodynamic coexistence of multiple VOx phases and clarify the origin of the observed long-term retention in the ECRAM devices. Further, we demonstrate single devices that can be voltage programmed to exhibit synaptic, neuronal, and reconfigurable logic gate functionalities. Therefore, we not only uncover the phase coexistence mechanism that may help device design, but also demonstrate the circuit-level applications of reconfigurability.
| Original language | English |
|---|---|
| Article number | 085001 |
| Journal | Physical Review Materials |
| Volume | 9 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 8 2025 |
| Externally published | Yes |
Funding
This work was supported by the Center for Reconfigurable Electronic Materials Inspired by Nonlinear Neuron Dynamics (ReMIND), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Additional support came from the DOE Office of Science Research Program for Microelectronics Codesign (sponsored by ASCR, BES, HEP, NP, and FES) through the Abisko Project (Program Manager: Robinson Pino at ASCR), the Laboratory-Directed Research and Development (LDRD) program at Sandia National Laboratories. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE's National Nuclear Security Administration under Contract No. DENA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.B.T.Z., S.O., T.D.B., and A.A.T. designed the experiments, characterized the devices and analyzed the data. P.F., S.P.B., and J.A. fabricated the devices. J.D.S. performed transmission electron microscopy and analysis. A.V.I. performed ToF-SIMS analysis. S.P.B., B.A.A.B., A.L.M., H.L., and P.B. performed theory and modeling. All authors contributed to the writing and editing of the manuscript. This work was supported by the Center for Reconfigurable Electronic Materials Inspired by Nonlinear Neuron Dynamics (ReMIND), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Additional support came from the DOE Office of Science Research Program for Microelectronics Codesign (sponsored by ASCR, BES, HEP, NP, and FES) through the Abisko Project (Program Manager: Robinson Pino at ASCR), the Laboratory-Directed Research and Development (LDRD) program at Sandia National Laboratories. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE's National Nuclear Security Administration under Contract No. DENA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.