Electrically Induced Phase Transition and Synaptic Functionality in MoTe 2 /Graphene Memristors

Two‐dimensional (2D) transition‐metal dichalcogenides offer electrically accessible polymorphisms for next‐generation memory and neuromorphic applications. Here, we demonstrate an electrically induced reversible phase transition between semiconducting 2H and metallic 1T′ MoTe 2 in a vertical Au/Ti/MoTe 2 /graphene memristor with a laterally contacted graphene electrode. The switching process is accompanied by the formation of a thin amorphous MoTe 2 interfacial region, which is proposed to serve as a defect‐rich interfacial region that facilitates reversible phase evolution and gradual conductance modulation. The device exhibits clear bipolar switching with retention exceeding 10 5 s, pulse endurance above 10 5 cycles, and ultrafast SET and RESET switching times down to 30 ns. Furthermore, key synaptic functionalities—including long‐term potentiation and depression, paired‐pulse facilitation, and spike‐timing‐dependent plasticity—are reliably emulated. Correlative electrical measurements combined with atomic‐scale scanning transmission electron microscopy (STEM) and electron energy‐loss spectroscopy (EELS), together with x‐ray photoelectron spectroscopy (XPS), reveal that switching is associated with a controllable amorphous/2H ↔ amorphous/1T′ phase transition without detectable stoichiometric variation, induced under electrical bias through coupled electric‐field and Joule‐heating effects. This compositionally invariant mechanism establishes a direct link between structural phase modulation and device functionality, highlighting the potential of phase‐engineered 2D materials for future nonvolatile memory and neuromorphic computing systems.