Ultrasensitive Hydrogen Detection Using GNRFET Sensor: Multimetric Optimization via Geometry, Temperature, and Oxygen...

Area of Science:

• Nanotechnology
• Materials Science
• Sensor Technology

Background:

• Graphene nanoribbon field-effect transistors (GNRFETs) show promise for gas sensing applications.
• Palladium (Pd) gating enhances sensitivity in GNRFET-based sensors.
• Understanding environmental factors like oxygen is crucial for sensor performance.

Purpose of the Study:

• To comprehensively analyze a Pd-gated GNRFET as a high-sensitivity hydrogen sensor.
• To investigate the influence of structural and environmental factors on sensor sensitivity.
• To model hydrogen adsorption and its impact on sensor performance.

Main Methods:

• Simulated hydrogen adsorption using pressure-dependent work-function modulation and interface coverage.
• Analyzed band diagrams, transmission spectra, local density of states, and transfer characteristics.
• Evaluated sensitivity using drain current change, threshold voltage shift, and subthreshold swing variation across various conditions (H2 pressure, temperature, gate length, nanoribbon width).

Main Results:

• Maximum threshold voltage sensitivity of ~300 mV at PH2=10-6 Torr (no O2), reduced to ~40 mV with 152 Torr O2.
• Current-based sensitivity is high at ultralow H2 pressures but decreases at higher pressures.
• Subthreshold-based sensitivity shows different pressure-dependent behavior compared to current-based sensitivity.
• Threshold voltage sensitivity is largely independent of device geometry, indicating robustness against fabrication variations.

Conclusions:

• Pd-gated GNRFETs demonstrate high potential as hydrogen sensors.
• Oxygen significantly impacts sensor sensitivity, highlighting the need for controlled environments.
• Threshold voltage shift is a reliable metric for hydrogen sensing, offering geometric tolerance for practical applications.