Stable Resistive Switching of Highly Polycrystalline Two-dimensional Molybdenum Ditelluride based Memristor Array

Two-dimensional (2D) materials have generated attention for neuromorphic computing applications, and are promising for use in low-power synaptic devices at the atomic scale. However, 2D material-based memristors are disadvantaged by the large stochastic forming process, which results in switching variability. In this study, we present a 2-inch wafer scale memristor array that contains nanometer-sized grains of highly polycrystalline 2H-MoTe₂ as an active medium and exhibits reliable resistive switching. The polycrystalline 2H-MoTe₂ films were synthesized on a 2-inch SiO₂/Si wafer by tailoring the Te flux through a Te vapor-confined method using a eutectic alloy. The synthesized films contain uniformly sized nanograins (~60 nm) and exhibit ultrahigh-density (1.37<b>×</b>10¹¹cm^-2) grain boundaries (GBs). These GBs provide confined defective paths to enable conduction, facilitating reliable resistive switching. Compared to single-crystalline 2H-MoTe₂-based memristors, the polycrystalline 2H-MoTe₂-based memristor (PMM) arrays show improved resistive switching uniformity and stable multi-level resistance states, along with high device yields (&gt;83.7%), small device-to-device variations (&lt;13.8%), and long retention times (&gt;10⁵s). Finally, this PMM shows linear analog synaptic plasticity under repeated pulses more than 2,500 and exhibits a learning accuracy of 96.05% for MNIST handwritten digit classification. The introduction of nanograins in the PMM represents a novel route to accelerate the use of 2D memristors in practical neuromorphic computing applications.