High-Field Electron Transport and High Saturation Velocity in Multilayer Indium Selenide Transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Physics

Background:

• High-frequency electronic devices require materials with high electron saturation velocity (υ_sat).
• Van der Waals (vdW) semiconductors offer tunable electronic properties for advanced applications.

Purpose of the Study:

• To investigate the high-field transport properties of multilayer indium selenide (InSe).
• To determine the saturation velocity (υ_sat) and its temperature dependence in encapsulated InSe.

Main Methods:

• Fabrication of multilayer InSe on hexagonal boron nitride (hBN) substrate.
• Encapsulation of InSe with a thin indium (In) layer.
• Measurement of high-field transport properties and electron mobility at room and cryogenic temperatures.

Main Results:

• Achieved an impressive electron mobility of 2600 cm²/(V s) at room temperature.
• Demonstrated a saturation velocity (υ_sat) exceeding 2 × 10⁷ cm/s, surpassing other gapped vdW semiconductors.
• Observed a 50-60% improvement in υ_sat upon cooling to 80 K.
• Identified an optical phonon energy (ℏω_op) of 23-27 meV for InSe.
• Measured υ_sat values higher than predicted by optical phonon emission models, indicating weak electron-phonon scattering.

Conclusions:

• Multilayer InSe exhibits superior saturation velocity (υ_sat) due to weak electron-phonon scattering.
• The high υ_sat of InSe makes it a promising candidate for high-frequency electronics.
• Potential applications include control of cryogenic quantum computers.