Room-Temperature WSe₂ Impact Ionization Field-Effect Transistor Based on a Stepwise Homojunction.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Device Physics

Background:

• Low subthreshold swing (SS) is critical for power-efficient transistors, aiming below the 60 mV/decade Boltzmann limit.
• Impact ionization field-effect transistors (II-FETs) offer steep SS and high performance but face fabrication complexity.
• Developing advanced transistors requires overcoming fabrication challenges for array integration.

Purpose of the Study:

• To introduce a novel II-FET design overcoming fabrication hurdles.
• To demonstrate ultra-low SS and high performance using a new material junction.
• To explore temperature-dependent performance improvements for energy-efficient electronics.

Main Methods:

• Fabrication of a stepwise van der Waals WSe2 homojunction.
• Characterization of the II-FET's electrical properties at room and low temperatures.
• Analysis of subthreshold swing, multiplication factor, and current on/off ratio.

Main Results:

• Achieved a low SS of 3.09 mV/decade at room temperature.
• Demonstrated a high multiplication factor exceeding 10^4.
• Observed further SS improvement to 0.25 mV/decade at low temperatures.
• Reported a current on/off ratio >10^5 and on-state current density of ~1 µA/µm.

Conclusions:

• The novel WSe2 homojunction II-FET offers a promising pathway for energy-efficient electronics.
• The device overcomes fabrication complexity challenges associated with traditional II-FETs.
• This work paves the way for next-generation, power-saving electronic devices.