Boosting Neuromorphic Synapses through Alloying-Induced Trap Engineering in Two-Dimensional Mo1– x W x S2

Abstract

Two-dimensional transition metal dichalcogenides (TMDs) are promising candidates for next-generation neuromorphic electronics owing to their tunable electronic structure and defect-mediated charge dynamics. Here, we demonstrate alloying engineering of Mo1–xWxS2 (0 ≤ x ≤ 1) via chemical vapor deposition to precisely tailor the lattice strain, defect density, and optoelectronic properties. Structural and spectroscopic analyses confirm the homogeneous distribution of Mo and W atoms within the alloy lattice, accompanied by strain fields that enhance trap-mediated charge processes. Optical measurements reveal composition-dependent bandgap tuning and exciton lifetimes, with near-equiatomic MoWS2 exhibiting the strongest non-radiative recombination pathways. Synaptic field-effect transistors based on these alloys display pronounced hysteresis windows of up to 22 V, high interface trap densities, and robust low-frequency noise characteristics, effectively linking alloy disorder to defect-driven memory functions. Remarkably, near-equiatomic MoWS2 synaptic devices emulate key biological features, including a paired-pulse facilitation index of up to 188%, dynamic learning–forgetting–relearning cycles, stable long-term potentiation/depression, and an 87.95% recognition accuracy in CNN simulation. These findings establish alloy-engineered Mo1–xWxS2 as a powerful platform for defect–strain coupling and neuromorphic functionality in two-dimensional materials.