Thermally Assisted Nonvolatile Memory in Monolayer MoS₂ Transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Field-effect transistors (FETs) based on two-dimensional (2D) materials are promising for next-generation electronics.
• Understanding charge dynamics and memory effects in 2D FETs is crucial for device applications.

Purpose of the Study:

• To investigate a novel form of thermally-assisted hysteresis in monolayer MoS2 FETs.
• To explore the underlying mechanisms and potential applications of this phenomenon.

Main Methods:

• Fabrication and characterization of monolayer and bilayer MoS2 FETs.
• Electrical measurements of transistor transfer curves at elevated temperatures (above 400 K).
• Analysis of gate-voltage sweep parameters to understand hysteresis origins.

Main Results:

• Demonstrated thermally-assisted hysteresis in monolayer MoS2 FETs with a large gate-voltage window and current modulation of ~10^2.
• Identified charge injection into the SiO2 gate dielectric as the likely cause of hysteresis.
• Observed significant suppression of hysteresis in bilayer MoS2, indicating the importance of weak screening in monolayers.

Conclusions:

• Monolayer MoS2 FETs exhibit thermally-assisted memory effects due to charge injection, enhanced by weak screening.
• Programmable memory operation was successfully demonstrated by exploiting the hysteretic characteristics.
• This work paves the way for new thermally assisted memory devices utilizing 2D semiconductors.