Vertically Aligned WS2 Layers for High-Performing Memristors and Artificial Synapses

Inspired by the human brain, the quest for high-performing neuromorphic architecture has recently gained more attention, which can be achieved by two-terminal memristors. However, due to random and uncontrolled filament formation during a typical switching process, conventional memristors suffer from severe shortcomings such as temporal/spatial reproducibility as well as trivial sensitivity against applied spikes, however all these properties are crucial for accurate and quick information processing. Here, reproducible and robust two serially connected memristors comprised of ZnO and vertically grown WS2 layers are reported. The device demonstrates remarkable tunable dynamic range along with comprehensive synaptic functions, including short- to long-term plasticity, paired-pulse facilitation, and spike-timing-dependent plasticity. Vertically aligned WS2 layers confine the conduction along 1D channel and drastically enhance the performance. The dynamic processes of memorizing and forgetting are mimicked through a 3 x 3 memristive synapse array. A unique platform to design high-performing and reproducible artificial synapses for neuromorphic computing is provided.