Plasmon-Induced Graphene/Silicon Schottky Junctions for Ultrasensitive Gas Sensing

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Metal oxide gas sensors can be improved by light modulation.
• Plasmonic sensors utilize localized surface plasmon resonance (LSPR) in noble metals for enhanced properties.
• Chemiresistive sensors decorated with plasmonic nanoparticles offer an alternative to optical sensing methods.

Purpose of the Study:

• To demonstrate a chemiresistive gas sensor utilizing a graphene/silicon Schottky junction decorated with palladium nanoparticles (PdNPs).
• To investigate the enhancement of gas sensing properties through localized surface plasmon resonance (LSPR) and light modulation.
• To establish a simplified method for recording plasmonic gas sensor responses using only DC characteristic measurements.

Main Methods:

• Fabrication of a graphene/silicon Schottky junction gas sensor decorated with palladium nanoparticles (PdNPs).
• Excitation of PdNPs using UV light at different wavelengths (255 nm, 275 nm, 355 nm) to induce LSPR.
• Measurement of sensor responses to NO2 and NH3 gases based on DC characteristics.

Main Results:

• The highest sensitivity to NO2 and NH3 gases was achieved when the PdNPs were excited at their plasmonic resonant wavelength of approximately 275 nm.
• The LSPR-modulated sensor response to NO2 gas was nearly 14 times greater than that for NH3 gas.
• An ultralow detection limit of 4 ppb for NO2 gas was achieved, demonstrating significant sensitivity enhancement.

Conclusions:

• Light modulation, specifically at the LSPR wavelength, significantly enhances both sensitivity and selectivity of plasmonic chemiresistive gas sensors.
• The developed graphene/silicon Schottky junction sensor decorated with PdNPs offers a promising platform for highly sensitive and selective gas detection.
• Simplified DC characteristic measurements provide an effective method for evaluating plasmonic gas sensor performance.