WSe₂ Negative Capacitance Field-Effect Transistor for Biosensing Applications

Area of Science:

• Materials Science
• Nanotechnology
• Biosensors

Background:

• Field-effect transistor (FET) biosensors using 2D materials offer high sensitivity and label-free detection but are limited by the Boltzmann limit (SS > 60 mV/dec) and gate leakage in liquid environments.
• Enhancing FET biosensor sensitivity and stability in aqueous solutions remains a significant challenge for accurate and reliable detection.

Purpose of the Study:

• To introduce a novel two-dimensional material WSe2 negative capacitance field-effect transistor (NCFET) for biosensing applications.
• To overcome the Boltzmann limit for subthreshold swing (SS) and reduce gate leakage in FET biosensors operating in aqueous solutions.

Main Methods:

• Fabrication of a WSe2-based NCFET utilizing an Al2O3/HfZrO (HZO) bilayer dielectric.
• Characterization of the NCFET's electrical properties, including subthreshold swing (SS) and gate leakage in aqueous solution.
• Demonstration of biosensing capabilities through pH detection and enzyme-catalyzed glucose detection.

Main Results:

• The WSe2 NCFET achieved a minimum subthreshold swing (SS) of 56 mV/dec in aqueous solution, surpassing the Boltzmann limit.
• pH detection sensitivity reached 994 pH-1, an order of magnitude higher than traditional WSe2 FET biosensors.
• The NCFET biosensor demonstrated specific glucose detection with high sensitivity (4800 A/A in 5 mM glucose) and a low detection limit (10-9 M), and successfully detected glucose in sweat.

Conclusions:

• The developed WSe2 NCFET effectively overcomes the SS limitation and reduces gate leakage in liquid environments, significantly enhancing biosensor performance.
• This NCFET technology offers a promising platform for highly sensitive and stable label-free biosensing, with potential applications in diagnostics and environmental monitoring.
• The NCFET biosensor's ability to detect glucose in sweat highlights its potential for real-time, non-invasive health monitoring.