In Memory Energy Application for Electrochemical Random Access Memory

This work explores the innovative concept of a hybrid dual-behavior device, based on emerging nonvolatile memory technology, for both data retention and energy storage. Electrochemical random access memory (ECRAM) is considered a major candidate as next-generation memory, thanks to its promising performances in terms of scalability and CMOS process compatibility. In particular, three-terminal synaptic transistors (SynT) offer an ion conductor-gated control from which ion doping content can be monitored with high energy efficiency via redox reactions, thus decoupling write-read actions and improving the linearity of programming states for neuromorphic computing 1 . Its working mechanisms, based on faradaic processes, motivate the study on the feasibility of operating ECRAM also as energy storage element. To evaluate the energy capability, various electrochemical characterizations are presented. Cyclic voltammetry tests reveal that the cells behave as standard electrochemical storage elements when investigating the impact of the scan rate, maximum positive voltage, and area on the reduction peak. Storage capability amounts up to 1.5µAh.cm -2 have been obtained, two decades higher than deep trench capacitor existing solutions, while showing outstanding synaptic behavior: A nonvolatile conductance modulation (<75 nS) is achieved through reversible lithium intercalation into the channel, and synaptic functions, such as long-term potentiation/depression involve ultralow switching energy of 2 fJ μm −2 . Moreover, this SynT shows excellent endurance (>10 5 weight updates) and recognition accuracy (>95% on the MNIST data test using crossbar simulations). Finally, design concepts are proposed, where ECRAM “in-memory energy” technology would be a newfangled approach to meet the needs of various emerging and standard applications. Reference Nguyen, N. et al. An Ultralow Power Li x TiO 2 -Based Synaptic Transistor for Scalable Neuromorphic Computing. Adv. Electron. Mater. 2200607 , 2200607 (2022). Figure 1. Schematic view of the elaborated SynT, and corresponding dual energy and data storage properties: vertical gate stack is a nanobattery with energy storage function while lateral architecture allows for conductance modulation and data storage. Figure 1