Nanoporous\nSilicon Thin Film-Based Hydrogen Sensor\nUsing Metal-Assisted Chemical Etching with Annealed Palladium Nanoparticles

Abstract

This\narticle reports a nanoporous silicon (Si) thin-film-based\nhigh-performance and low-power hydrogen (H₂) sensor fabricated\nby metal-assisted chemical etching (MaCE). The nanoporous Si thin\nfilm treated with Pd-based MaCE showed improvement over a flat Si\nthin film sensor in H₂ response (Δ<i>I</i>/<i>I</i>₀ = 4.36% → 12.4% for 0.1% H₂). Furthermore, it was verified that the combination of thermal\nannealing of Pd and subsequent MaCE on the Si thin film synergistically\nenhances the H₂ sensitivity of the sensor by 65 times as\ncompared to the flat Si thin film sensor (Δ<i>I</i>/<i>I</i>₀ = 4.36% → 285% for 0.1% H₂). This sensor also showed a very low operating power of 1.62\nμW. After the thermal treatment, densely packed Pd nanoparticles\nagglomerate due to dewetting, which results in a higher surface-to-volume\nratio by well-defined etched holes, leading to an increase in sensor\nresponse.