Circular-Gate Nanoscale Air Channel Transistors: Achieving ultralow Subthreshold Swing and Working Voltage

Area of Science:

• Semiconductor Physics
• Advanced Materials Science
• Nanoelectronics

Background:

• Traditional Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) face performance limitations in extreme environments due to physical constraints like Boltzmann's law.
• Nanoscale Air Channel Transistors (NACTs) offer a potential solution by utilizing a vacuum-like channel and Fowler-Nordheim tunneling.

Purpose of the Study:

• To propose and fabricate a novel Circular Gate Nanoscale Air Channel Transistor (CG-NACT).
• To evaluate the performance characteristics of CG-NACTs, focusing on subthreshold swing, current drive, and stability.

Main Methods:

• Fabrication of CG-NACTs on a 4-inch silicon wafer using a CMOS-compatible process.
• Implementation of an innovative gate control mechanism for enhanced transistor performance.
• Characterization of electrical properties, including subthreshold swing (SS) and on/off ratio.
• Testing device stability under high temperatures (up to 150°C) and irradiation.

Main Results:

• Achieved an ultralow subthreshold swing (SS) of 0.15 mV/decade, with an average of 1.5 mV/decade over three decades of drain current.
• Demonstrated milliamper-level drain current at a low operating voltage of 0.7 V.
• Obtained a maximum on/off ratio of 7.82×10⁶.
• Confirmed high operational stability at elevated temperatures and under irradiation.

Conclusions:

• The developed CG-NACTs exhibit superior performance compared to traditional MOSFETs, particularly in terms of subthreshold swing.
• CG-NACTs show promise for applications requiring high performance and reliability in extreme environments.
• Successfully demonstrated the first inverter circuit designed using CG-NACTs, showcasing practical applicability.