High-Mobility Indium Native Oxide Transistors via Liquid-Metal Printing in Air.

Area of Science:

• Materials Science
• Electronics Engineering
• Nanotechnology

Background:

• Oxide semiconductors are crucial for advanced electronics, but high mobility often relies on expensive vacuum processing.
• Developing cost-effective, low-temperature methods for high-performance oxide semiconductors is essential for next-generation devices.

Purpose of the Study:

• To investigate the potential of ultrathin indium oxide (InO_x) prepared by liquid-metal printing (LMP) as a channel material for field-effect transistors (FETs).
• To evaluate the electrical performance, stability, and integration compatibility of LMP-InO_x FETs.

Main Methods:

• Fabrication of ultrathin (5 nm) InO_x films using ambient-air liquid-metal printing (LMP) at a low temperature (250 °C).
• Characterization of InO_x film structure and properties.
• Fabrication and testing of InO_x FETs using the transfer length method and integration with HfO₂ gate dielectrics.
• Postfabrication oxygen plasma treatment for enhancement-mode operation and inverter demonstration.

Main Results:

• LMP-InO_x films were polycrystalline with large grains extending through the film thickness.
• InO_x FETs achieved a high conductivity mobility (μ_CON) of 125 cm² V^-1 s^-1.
• Integrated InO_x FETs with HfO₂ exhibited high field-effect mobility (μ_FE) of 107 cm² V^-1 s^-1, an on/off ratio >10⁷, and stable operation over 10⁴ cycles.
• Enhancement-mode operation and a depletion-load inverter with a voltage gain of 69.8 V/V were achieved.

Conclusions:

• Liquid-metal printing provides a low-temperature, cost-effective method for producing high-performance InO_x channel materials.
• LMP-InO_x demonstrates significant potential for high-performance, power-efficient transistors in next-generation oxide electronics.
• The compatibility with standard fabrication processes suggests broad applicability in future electronic devices.