Role of Point Defects and Ion Intercalation in Two-Dimensional Multilayer Transition Metal Dichalcogenide Memristors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional materials, particularly transition metal dichalcogenides (TMDs), show promise for neuromorphic computing due to their synapse-like properties and nanoscale footprint.
• Understanding the physical mechanisms in TMD memristors is crucial for advancing their reliable performance.
• The precise contribution of defects and metal atoms to memristance in multilayer TMDs remains unclear.

Purpose of the Study:

• To systematically investigate the impact of intrinsic point defects and metal atoms on the out-of-plane conductivity of multilayer TMDs.
• To clarify the role of intrinsic point defects in forming conductive channels for memristive behavior.
• To determine the necessity of metallic atoms for enabling resistive switching in TMD-based memristors.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Non-equilibrium Green's function (NEGF) formalism.
• Analysis of molybdenum disulfide (MoS2) and platinum disulfide (PtS2) with 2H and 1T structures, respectively.

Main Results:

• Intrinsic sulfur vacancies, the dominant defects in MoS2 and PtS2, do not independently cause resistive switching under external bias.
• The presence of metallic atoms is demonstrated to be essential for triggering the memristive mechanism.
• Intrinsic point defects alone are unlikely to create a controllable conductive channel for valence change memory devices in multilayer TMDs.

Conclusions:

• Metallic atoms are critical for the memristive effect in TMDs, not intrinsic point defects alone.
• The selection of metal electrodes is vital for fabricating and optimizing TMD memristors.
• Further research should focus on the interplay between defects and metallic elements for advanced memristor design.