Bio-Realistic Synaptic-Replicated “V” Type Oxygen Vacancy Memristor

The development of an artificial synaptic device is essential for the construction of a brain-like neuromorphic computing architecture. In this study, the goal is to create a multi-layer HfO_x memristor with a “V” type oxygen vacancy (V_o) distribution to mimic the function of calcium ions (Ca²⁺) during synaptic information transmission. By adjusting voltage and compliance current (I_cc), the HfO_x memristor can open or close different levels of volt-controlled Ca²⁺ channels, thus enabling the replication of synaptic structure, neurotransmitter release/acceptor, and information transmission. A mathematical model is adopted to describe the behavior of volt-controlled Ca²⁺ channels, which demonstrates that the device exhibits consistent characteristics with biological synapses. The device forms an “hourglass” conductive filament (CF) within its middle functional layer, allowing for precise control over filament formation and positioning. This results in ultra-low power consumption for erasing (581 fJ), fast erasing speed (10 ns), and a low resistance difference coefficient of only 1.8%. Furthermore, the device successfully simulates the physical dynamics of Ca²⁺ during short-term potentiation (STP) and long-term potentiation (LTP) in biological synapses while replicating various guided synaptic behaviors. This study provides a straightforward method for memristors to realize bio-realistic artificial neuromorphic applications.