A high-performance room-temperature hydrogen sensor based on Pd nanoparticle-decorated β-Ga2O3 prepared by mist-CVD

Hydrogen is a promising clean energy carrier, but its high flammability demands reliable sensing at room temperature with low power consumption. Here, we demonstrate a room-temperature hydrogen sensor based on Pd-decorated β-Ga2O3 thin films grown by mist chemical vapor deposition (mist-CVD), a non-vacuum thin-film deposition technique. The device delivers a large sensing response of ∼1300 toward 1% H2 with detectable responses down to 10 ppm. Owing to the wide bandgap of β-Ga2O3, the sensor exhibits an intrinsically low baseline current at the pA level, allowing hydrogen-induced carrier modulation triggered by Pd surface reactions to be clearly resolved. The device further shows excellent selectivity to H2 over common interfering gases, robust operation up to 85% relative humidity, and stable performance over 98 days without encapsulation. A spillover-assisted charge-modulation mechanism, involving Pd-catalyzed hydrogen dissociation and activation of oxygen-vacancy-related donor states in β-Ga2O3, is proposed to account for the strong room-temperature response. These results highlight Pd/β-Ga2O3 sensing platforms fabricated by mist-CVD as promising candidates for low-power and durable hydrogen detection.