Gate-voltage-induced reversible electrical phase transitions in Mo_0.67W_0.33Se₂ devices

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional transition-metal dichalcogenides exhibit tunable electrical phase transitions.
• These transitions are driven by structural and quantum-state changes.
• Applications in semiconducting and quantum electronics are highly sought after.

Purpose of the Study:

• To investigate gate-voltage-induced reversible electrical phase transitions in Mo0.67W0.33Se2 (MoWSe) field-effect transistors.
• To understand the behavior of these transitions concerning temperature, layer number, and gate voltage.
• To explore the underlying mechanisms and potential applications of these phenomena.

Main Methods:

• Fabrication of Mo0.67W0.33Se2 (MoWSe) field-effect transistors on SiO2/Si substrates.
• Electrical characterization including current-voltage measurements at varying temperatures and gate voltages.
• Analysis of thermal activation energies and transfer curves to identify phase transition characteristics.
• Hysteresis measurements to confirm the reversibility of the electrical transitions.

Main Results:

• Reversible electrical phase transitions were induced by gate voltage in MoWSe transistors between 150 K and 200 K.
• A new electron-doped conducting channel emerged in the 2H phase depletion region.
• Distinct thermal activation energies for the conducting and 2H-phase branches were observed.
• Negative differential transconductance and deflection points in transfer curves indicated phase transition behavior.
• Hysteresis measurements confirmed the reversible nature of the observed electrical transitions.

Conclusions:

• Gate-voltage control enables reversible electrical phase transitions in MoWSe.
• The observed transitions involve significant modification of the electrical band structure at the Fermi level.
• These findings offer a pathway for novel electronic devices based on tunable phase transitions in 2D materials.