SAW Hydrogen Sensors with Pd/SnO₂ Layers

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Surface Acoustic Wave (SAW) sensors are crucial for gas detection.
• Tin dioxide (SnO2) is a widely studied material for gas sensing applications.
• Palladium (Pd) is known to catalyze hydrogen reactions.

Purpose of the Study:

• To investigate the effect of deposition pressure on the morphology of Pd/SnO2 bilayers for SAW sensors.
• To evaluate the performance of these sensors in detecting hydrogen gas.
• To determine the influence of SnO2 and Pd film morphology on sensor response and selectivity.

Main Methods:

• Pd/SnO2 bilayers were fabricated using pulsed laser deposition (PLD) at varying pressures (100 and 700 mTorr).
• Film morphology was characterized using scanning electron microscopy (SEM).
• SAW sensors were tested with different hydrogen concentrations (0.2-2%) and selectivity tests were performed for H2, N2, O2, and CO2.

Main Results:

• The sensor with the most porous SnO2 film (deposited at 700 mTorr) exhibited the best performance, with a sensitivity of 0.21 Hz/ppm and a limit of detection (LOD) of 142 ppm.
• SnO2 film morphology significantly impacted sensor results, more so than Pd morphology.
• Palladium acted as an effective catalyst, substantially improving hydrogen sensitivity and sensor selectivity.

Conclusions:

• Optimizing SnO2 film morphology through deposition pressure is key to enhancing SAW sensor performance for hydrogen detection.
• The use of Pd as a catalyst significantly boosts the sensitivity and selectivity of SnO2-based SAW sensors for hydrogen.
• These findings contribute to the development of more effective hydrogen gas sensors.