Volatile Memristive Devices With Tunable Temporal Dynamics For Event-Based Sensing.

Abstract

Volatile memristive devices with controllable temporal dynamics enable adaptation to diverse temporal coding tasks, making them attractive for low-power neuromorphic edge applications that process asynchronous sensory streams. However, most reported volatile memristors rely on abrupt filamentary switching, suffering from high variability, unreliable operation, and the need for current compliance and forming steps. In this work, an area-dependent volatile memristive device based on a Pt/ <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>α</mi></math> - <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>SrTiO</mi> <mn>3</mn></msub> </math> / <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>TaO</mi> <mi>x</mi></msub> </math> /Ta stack is presented, exhibiting ionic-based volatility and a CMOS BEOL-compatible process flow. The device combines low variability with forming-free, self-compliant, rectifying operation and gradual, analog-like switching, achieving an ON/OFF ratio of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>∼</mo> <msup><mn>10</mn> <mn>3</mn></msup> </mrow> </math> . An in-depth experimental and physical analysis of the mechanisms governing current transport and volatile behavior is provided. By exploiting the device's rich ionic dynamics, its volatility can be systematically tuned through applied stimulus and stack engineering, yielding decay time constants from tens of milliseconds to several seconds. A reliability study, including endurance and multilevel operation, demonstrates reproducible access to distinct volatile states. Finally, it is shown how a complete system, combining the device with spiking neuron models and CMOS circuitry, could exploit its programmable temporal dynamics for event-based vision, with the wide range of decay constants supporting multiple sensory modalities.