Ferroelectric‐Driven Nonvolatile Phase Transition in MoTe 2 Transistors With an Expanded Memory Window

ABSTRACT Polymorphic MoTe 2 offers a unique opportunity for phase‐transition memristors due to its reversible structural transitions between semiconducting (2H) and metallic (1T′) phases. Although gate‐tunable phase transitions have been demonstrated, the presence of mobile ions in electrolyte gating leads to volatile behavior. Here, we demonstrate a phase‐transition ferroelectric field‐effect transistor (PT‐FeFET) employing a polymorphic MoTe 2 channel and a Hf 0.5 Zr 0.5 O 2 (HZO) ferroelectric gate insulator. The ferroelectric polarization of the HZO layer induces an electrically driven, long‐term nonvolatile phase transition in the MoTe 2 channel. Unlike conventional FeFETs, in which the memory window is confined between the SET and RESET threshold voltages ( V th ), the 1T′ metallic phase in the MoTe 2 PT‐FeFET eliminates the OFF state and the corresponding SET V th , thereby enabling expansion of the memory window across the entire voltage range below the RESET V th . Consequently, the device exhibits both a wide memory window (82.5%) and a high ON/OFF current ratio (10 6 ), outperforming conventional FeFETs. Owing to its wide memory window, the PT‐FeFET accesses the full spectrum of synaptic weights (0–1) with near‐ideal linearity ( β = 0.9). As a result, the PT‐FeFET achieves 82% accuracy in CIFAR‐10 classification, surpassing the 59%–75% accuracy of conventional FeFETs.