Enhanced analog switching in Ta2O5/HfO2 bilayer resistive switching device for improved synaptic behavior in neuromorphic computing

초록

Memristor with analog resistive switching (RS) characteristics has potential for effective utilization in hardware neuromorphic systems. We investigated the response by applying identical pulses to filamentary RS devices to induce synaptic functions. This study examined the effects of inserting Al<inf>2</inf>O<inf>3</inf> or HfO<inf>2</inf> into Ta<inf>2</inf>O<inf>5</inf>-based RS device on its switching behavior to analyze long-term plasticity. Abrupt potentiation (or depression) behavior in Ta<inf>2</inf>O<inf>5</inf> single layer structure may be inappropriate for neuromorphic applications. Thus, we proposed bilayer structures to alleviate abrupt conductance change. More linear and symmetric conductance modulation was confirmed in Ta<inf>2</inf>O<inf>5</inf>/HfO<inf>2</inf> device compared to Ta<inf>2</inf>O<inf>5</inf>/Al<inf>2</inf>O<inf>3</inf> device: exhibiting high potential as a synaptic device for neuromorphic computing. High learning accuracy was verified in Ta<inf>2</inf>O<inf>5</inf>/HfO<inf>2</inf> device through neural network simulation. Among all devices, its RS behavior was most consistent. This could originate from fewer remaining nucleation sites for reformation of conductive filament (CF). This stable CF reformation might contribute to reliable synaptic behavior. © 2025

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