Robust Metal and Semiconductor Phase Transition Memristor Using Ag-Intercalated Transition Metal Dichalcogenide.

Abstract

Metal (1T/1T')-semiconductor (2H) phase transition memristors (PTMEMs) based on intercalated alkali metal ions (Li⁺) in transition metal dichalcogenides (TMDs) exhibit excellent electrical properties, including heterosynaptic plasticity. However, the low stability of Li⁺ ions limits retention and on/off ratios of the PTMEMs. Here, a phase transition in MoTe₂ induced by intercalated Ag⁺ ions is demonstrated for the first time, enabling robust memristor operation. The migration of Ag⁺ ions, controlled by voltage biases, clearly realizes reversible 2H-1T/1T' phase transitions, as revealed by transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman mapping. The memristive mechanism of MoTe₂ shifts from doping (4-8 h) to phase transition (12 h) as Ag intercalation time increases, achieving a 200 000 on/off ratio at a 4 nm thickness. MoTe₂ exhibits the most evident phase transition due to its low transition barrier (0.84) compared to other TMDs (>1.22). Intercalated Ag⁺ ions provide outstanding memristive performance over Li⁺ ions, with a 100 times higher on/off ratio, 300 times better retention, and 8 times lower non-linearity (β_Ag = 0.5-0.6, β_Li = 4.0). Ag⁺MoTe₂ PTMEM achieves 91.7% accuracy in MNIST recognition, surpassing the 81.7% accuracy of Li⁺MoS₂ PTMEM. These findings demonstrate that Ag⁺MoTe₂ PTMEM holds great potential for advanced memory-based neural network applications.