Ion-Induced Phase Changes in 2D MoTe<sub>2</sub> Films for Neuromorphic Synaptic Device Applications.

Rupom, Rifat Hasan; Jung, Moonyoung; Pathak, Anil; Park, Jeongmin; Lee, Eunho; Ju, Hyeon-Ah; Kim, Young-Min; Chyan, Oliver et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

Two-dimensional molybdenum ditelluride (2D MoTe<sub>2</sub>) is an interesting material for artificial synapses due to its unique electronic properties and phase tunability in different polymorphs 2H/1T'. However, the growth of stable and large-scale 2D MoTe<sub>2</sub> on a CMOS-compatible Si/SiO<sub>2</sub> substrate remains challenging because of the high growth temperature and impurity-involved transfer process. We developed a large-scale MoTe<sub>2</sub> film on a Si/SiO<sub>2</sub> wafer by simple sputtering followed by lithium-ion intercalation and applied it to artificial synaptic devices. The Al<sub>2</sub>O<sub>3</sub> passivation layer allows us to develop a stable 1T'-MoTe<sub>2</sub> phase by preventing Te segregation caused by the weak bonding between Mo and Te atoms during lithiation. The lithiated MoTe<sub>2</sub> film exhibits excellent synaptic behavior such as long-term potentiation/depression, a high <i>I</i><sub>on</sub>/<i>I</i><sub>off</sub> ratio (≈10<sup>3</sup>) at lower sweep voltage, and long-term retention. The in situ Raman analysis along with a systematic microstructural analysis reveals that the intercalated Li ion can provide an efficient pathway for conducting filament formation.