Ultralow-Power Circuit and Sensing Applications Based on Subthermionic Threshold Switching Transistors.

Area of Science:

• Materials Science and Engineering
• Electrical Engineering
• Optoelectronics

Background:

• State-of-the-art electronics and optoelectronics face challenges in minimizing power consumption.
• Steep-slope field-effect transistors (FETs) offer a solution by overcoming the "Boltzmann limit" with sub-60 mV/dec subthreshold swing (SS).
• Existing devices often lack the abrupt transition characteristics required for highly efficient circuits.

Purpose of the Study:

• To develop a novel steep-slope transistor, termed TS-FET, by integrating nanoscale copper-based resistive-filamentary threshold switch (TS) with an Indium Gallium Zinc Oxide (IGZO) channel-based FET.
• To investigate the electrical characteristics and device performance of the developed TS-FET.
• To explore potential circuit applications of the TS-FET, moving beyond device-centric studies.

Main Methods:

• Fabrication of a TS-FET by integrating a nanoscale copper-based threshold switch (TS) with an IGZO channel-based FET.
• Characterization of the TS-FET's turn-on characteristics, including subthreshold swing (SS), on/off ratio, and leakage current.
• Demonstration of circuit applications, including logic inverters, pulse-sensor amplification, and photodetectors using the TS-FET.

Main Results:

• The TS-FET exhibited an abrupt turn-on characteristic over five decades with an extremely low SS of 7 mV/dec.
• Achieved a high on/off ratio (>10^9) and a significant 40-fold decrease in ultralow leakage current, ensuring excellent repeatability and device yield.
• Demonstrated high performance in circuit applications: logic inverters with a voltage gain of ≈800 (intrinsic gain >1000), wearable pulse sensor amplification by 450 times, and a photodetector with high responsivity (1.08 × 10^4 mA/W) and detectivity (1.03 × 10^20 Jones).

Conclusions:

• The developed TS-FET effectively overcomes the Boltzmann limit, offering a promising low-power strategy for advanced electronics.
• The device's sharp transition behavior and high performance enable efficient circuit applications, including logic operations and signal amplification.
• TS-FETs hold significant potential for energy-efficient integrated circuits and sensor-interconnected biomedical applications in wearable technology.