High-Performance InSe Transistors with Ohmic Contact Enabled by Nonrectifying Barrier-Type Indium Electrodes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Electrical contact quality is critical for the performance of two-dimensional (2D) semiconductor field-effect devices (FEDs).
• Schottky barriers at metal-semiconductor interfaces cause high contact resistance, limiting device conductance and carrier mobility.
• Ohmic contacts, characterized by nonrectifying or tunneling barriers, are essential for optimal device operation.

Purpose of the Study:

• To demonstrate a method for achieving nonrectifying (Ohmic) electrical contacts to layered indium selenide (InSe).
• To investigate the electronic properties and interface characteristics of indium (In) contacts on InSe.
• To enable high-performance 2D semiconductor devices through improved contact engineering.

Main Methods:

• Fabrication of field-effect devices using layered InSe and indium (In) as the contact metal.
• Electrical transport measurements at cryogenic (T = 2 K) and room temperatures.
• Characterization of the In-InSe interface using X-ray photoelectron spectroscopy (XPS).

Main Results:

• A nonrectifying barrier with a low barrier height (ΦB = 50 meV) was achieved at the In-InSe interface due to favorable band alignment.
• Ohmic contact behavior was confirmed at T = 2 K.
• High on-current (410 μA/μm) and excellent electron mobilities (3700 cm²/V·s at 2 K, 1000 cm²/V·s at room temperature) were demonstrated in In-InSe FEDs.
• XPS analysis indicated a reduction effect at the interface, supporting the improved contact quality.

Conclusions:

• Indium (In) forms excellent Ohmic contacts with layered indium selenide (InSe), significantly enhancing device performance.
• The favorable band alignment at the In-InSe interface is key to realizing nonrectifying contacts.
• This interface engineering approach offers a viable pathway for developing next-generation 2D semiconductor electronics.