Liquid-Metal-Printed Ultrathin Oxides for Atomically Smooth 2D Material Heterostructures

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Two-dimensional (2D) semiconductors are crucial for scaling complementary metal-oxide-semiconductor (CMOS) logic circuits.
• Integration challenges, particularly the lack of suitable high-k dielectrics, hinder the full potential of 2D materials.
• Achieving atomically smooth interfaces, small equivalent oxide thicknesses (EOTs), and low leakage currents are key requirements for advanced 2D devices.

Purpose of the Study:

• To report the development and application of large-area liquid-metal-printed ultrathin gallium oxide (Ga₂O₃) dielectrics for 2D electronics and optoelectronics.
• To demonstrate the capability of liquid metal printing for creating high-quality dielectric interfaces with 2D materials.
• To integrate these dielectrics into functional gate stacks for next-generation nanoelectronics.

Main Methods:

• Large-area fabrication of ultrathin Ga₂O₃ dielectrics using liquid metal printing.
• Direct visualization of Ga₂O₃/WS₂ interfaces to confirm atomic smoothness.
• Integration of Ga₂O₃/HfO₂ dielectric stacks using atomic layer deposition on chemical-vapor-deposition-grown monolayer WS₂.
• Electrical characterization of the fabricated devices to determine EOT, subthreshold swing, and gate leakage.

Main Results:

• Atomically smooth Ga₂O₃/WS₂ interfaces were achieved through conformal liquid metal printing.
• Demonstrated compatibility with atomic layer deposition for high-k Ga₂O₃/HfO₂ top-gate stacks.
• Achieved small equivalent oxide thicknesses (EOTs) of approximately 1 nm.
• Obtained excellent gate control with subthreshold swings as low as 84.9 mV/dec.
• Measured gate leakage currents well within the operational requirements for low-power logic circuits.

Conclusions:

• Liquid-metal-printed Ga₂O₃ offers a scalable solution for high-quality dielectric integration with 2D materials.
• This approach bridges a critical gap in enabling 2D materials for advanced nanoelectronics and optoelectronics.
• The demonstrated fabrication method paves the way for ultrascaled, low-power logic circuits utilizing 2D semiconductors.