High-Performance Carbon Nanotube Complementary Electronics and Integrated Sensor Systems on Ultrathin Plastic Foil

Area of Science:

• Materials Science
• Electronics Engineering
• Nanotechnology

Background:

• Flexible electronics require high-performance integrated circuits (ICs) on plastic substrates for advanced applications like continuous health monitoring.
• Existing complementary metal-oxide-semiconductor (CMOS) technology has been limited on plastics, hindering the development of sophisticated wearable devices.

Purpose of the Study:

• To implement high-performance carbon nanotube (CNT)-based CMOS technology on ultrathin plastic foil.
• To demonstrate the application of this technology in an integrated sensor system for human body monitoring.

Main Methods:

• Fabrication of p- and n-type CNT field-effect transistors (FETs) on 2.5 μm thick plastic foil.
• Characterization of transistor performance including transconductance, on-state current, mobility, and on/off ratio.
• Integration of CNT FETs into CMOS digital ICs and a ring oscillator circuit.
• Development of a skin-mounted humidity sensor system with signal processing.

Main Results:

• Achieved excellent and symmetric performance for both p- and n-type CNT FETs at a low operation voltage of 2 V.
• Demonstrated high mobility (up to 97.09 cm²·V⁻¹·s⁻¹) and a current on/off ratio of approximately 10⁵.
• Showcased mechanically robust devices withstanding a curvature radius down to 124 μm.
• Successfully implemented CMOS digital ICs, a 5 MHz ring oscillator, and a functional humidity sensor system.

Conclusions:

• CNT-based CMOS technology offers a viable solution for high-performance flexible electronics on plastic.
• This advancement paves the way for sophisticated, wearable integrated sensor systems for real-time human body monitoring.
• The developed technology enables complex functionalities like in situ signal processing in ultrathin, flexible devices.