Resistive Switching in α-In₂Se₃ Lateral Field-Effect Transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional ferroelectric semiconducting field-effect transistors (FeS-FETs) show promise for advanced memory and neuromorphic computing due to nonvolatile resistive switching.
• The precise mechanisms behind resistive switching in α-In₂Se₃ lateral devices, especially the roles of channel and contact resistance, are not fully understood.

Purpose of the Study:

• To spatially resolve gate-poling-dependent contact and channel resistances in α-In₂Se₃ FeS-FETs.
• To investigate the influence of spontaneous polarization and defect formation on resistive switching characteristics.
• To elucidate the mechanisms governing resistive switching for improved FeS-FET performance.

Main Methods:

• Kelvin probe force microscopy (KPFM) to map contact and channel resistances.
• Scanning photocurrent microscopy (SPCM) to quantify Schottky barrier height changes.
• Ex situ high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to observe structural defects.

Main Results:

• Both contact and channel resistances increased with positive poling and decreased with negative poling, correlating with Schottky barrier height modulation.
• Spontaneous polarization was confirmed to affect both channel and contact resistances in multidomain flakes.
• Clockwise resistive switching was observed even without clear ferroelectric polarization switching, often accompanied by stacking defects induced by gate poling.

Conclusions:

• Resistive switching in α-In₂Se₃ lateral devices is a complex phenomenon influenced by both reversible polarization switching and irreversible defect formation.
• The formation of stacking defects can impede domain wall motion, explaining the lack of abrupt switching thresholds.
• Improved domain wall control and defect mitigation strategies are crucial for enhancing FeS-FET performance and reliability in memory applications.