Ion-Induced Phase Changes in 2D MoTe₂ Films for Neuromorphic Synaptic Device Applications.

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Two-dimensional molybdenum ditelluride (2D MoTe₂) shows promise for artificial synapses due to its electronic properties and phase tunability.
• Challenges exist in growing stable, large-scale 2D MoTe₂ on CMOS-compatible substrates due to high temperatures and transfer processes.

Purpose of the Study:

• To develop a scalable method for fabricating 2D MoTe₂ films on Si/SiO₂ substrates.
• To investigate the application of these films in artificial synaptic devices.
• To understand the role of lithium-ion intercalation in stabilizing the material and enabling synaptic functions.

Main Methods:

• Fabrication of large-scale MoTe₂ films on Si/SiO₂ via sputtering and lithium-ion intercalation.
• Use of an Al₂O₃ passivation layer to stabilize the 1T'-MoTe₂ phase.
• Characterization using in situ Raman spectroscopy and microstructural analysis.
• Evaluation of synaptic behaviors including potentiation, depression, I_on/I_off ratio, and retention.

Main Results:

• Successful development of a large-scale MoTe₂ film on Si/SiO₂.
• Stabilization of the 1T'-MoTe₂ phase using Al₂O₃ passivation, preventing Te segregation.
• Demonstration of excellent artificial synaptic properties: long-term potentiation/depression, high I_on/I_off ratio (≈10³), and long-term retention.
• In situ Raman and microstructural analysis confirmed Li ion's role in conducting filament formation.

Conclusions:

• A simple and scalable method for producing stable 1T'-MoTe₂ films on Si/SiO₂ was established.
• The fabricated MoTe₂-based artificial synapses exhibit promising performance for neuromorphic computing.
• Lithium-ion intercalation is crucial for stabilizing the phase and facilitating the formation of conductive filaments essential for synaptic function.