Electrically Driven Reversible Phase Changes in Layered In₂ Se₃ Crystalline Film

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Phase-change memory (PCM) technology is crucial for advanced computing.
• Existing PCMs often rely on complex superlattice structures and melting-based phase transitions.
• There is a need for novel materials enabling simpler, more energy-efficient PCM devices.

Purpose of the Study:

• To report the first phase-change memory (PCM) utilizing Indium Selenide (In2Se3).
• To investigate the mechanism of phase transitions in In2Se3-based PCM.
• To explore the potential of In2Se3 for next-generation memory applications.

Main Methods:

• Fabrication of a PCM device using exfoliated In2Se3 layered film on a graphene electrode.
• Experimental characterization of SET/RESET switching behavior.
• Density Functional Theory (DFT) calculations to analyze phase stability and electronic properties.

Main Results:

• Demonstrated reversible phase changes between low-resistance (β phase) and high-resistance (γ phase) states in In2Se3.
• Identified SET/RESET switching mechanism involving the formation/annihilation of van der Waals (vdW) gaps and atomic reconfiguration.
• DFT calculations confirmed distinct bonding (octahedral vs. tetrahedral) and bandgaps (0.78 eV vs. 1.86 eV) for β and γ phases, respectively.
• Observed a metal-to-insulator transition during the β-to-γ phase change.

Conclusions:

• Monolithic In2Se3 layered films offer a novel approach for PCM fabrication.
• The demonstrated melting-free, low-entropy phase change mechanism in In2Se3 is advantageous over traditional PCM materials.
• This work paves the way for developing advanced, energy-efficient memory devices based on In2Se3.