Wafer-scale uniform non-ferroelectric κ-phase In₂Se₃ transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Device Physics

Background:

• Two-dimensional (2D) indium selenide (In₂Se₃) shows promise for processing-in-memory due to high carrier mobility and ferroelectricity.
• Challenges include the lack of wafer-scale, back-end-of-line (BEOL) compatible growth and polarization-induced hysteresis, hindering logic circuit applications.

Purpose of the Study:

• To develop a scalable, non-ferroelectric 2D In₂Se₃ material compatible with BEOL processes.
• To investigate the properties and device performance of the κ-phase In₂Se₃ for logic applications.

Main Methods:

• Thermal evaporation of non-ferroelectric κ-phase In₂Se₃ films over 4-inch wafers at temperatures below 450°C.
• Structural characterization to confirm phase, bandgap, and conduction type.
• Fabrication and testing of field-effect transistors (FETs) and complementary inverters.

Main Results:

• Uniform, wafer-scale κ-In₂Se₃ films were successfully grown with an indirect bandgap of 1.45 eV and n-type conduction.
• κ-In₂Se₃ FETs exhibited hysteresis-free operation, enhancement-mode behavior, and high field-effect mobility (39.3 cm²/Vs).
• A complementary inverter demonstrated full-swing operation and high voltage gain when integrated with a p-type FET.

Conclusions:

• κ-In₂Se₃ is a promising, scalable 2D semiconductor for BEOL-compatible logic integration.
• The elimination of hysteresis and high device performance open new avenues for advanced electronic applications.
• This work establishes a viable platform for next-generation logic circuits using 2D materials.