Highly Reliable Van Der Waals Memory Boosted by a Single 2D Charge Trap Medium.

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• Efficient charge storage is crucial for nonvolatile memory and artificial synapse applications.
• Two-dimensional (2D) materials offer potential for compact and reliable memory due to their atomically uniform interfaces.
• However, 2D materials have not been explored as charge trap media.

Purpose of the Study:

• To investigate the potential of 2D semiconducting materials as charge trap media.
• To demonstrate the efficacy of lead iodide (PbI2) in nonvolatile memory and artificial synapse devices.
• To explore the unique properties of PbI2 for advanced electronic applications.

Main Methods:

• Fabrication of a MoS2/PbI2 heterostructure device.
• Characterization of the device's memory performance, including memory window, write speed, on-off ratio, multilevel memory capability, endurance, and retention.
• Analysis of the role of native iodine vacancies in PbI2's ionic activity.

Main Results:

• The MoS2/PbI2 device exhibited a large memory window (120 V), fast write speed (5 µs), and high on-off ratio (~10^6).
• The device demonstrated multilevel memory (over 8 states), high reliability (10^4 cycles endurance), and good retention (1.2 × 10^4 s).
• PbI2 was identified as an excellent charge trap material requiring no complex synthesis or defect engineering.

Conclusions:

• Two-dimensional semiconducting PbI2 is a highly effective charge trap material for nonvolatile memory and artificial synapses.
• PbI2-based devices are simple to fabricate and offer superior performance metrics.
• The ionic activity of PbI2, stemming from iodine vacancies, enables versatile van der Waals heterostructures for integrated and multifunctional devices.