Nanoporous Silicon Thin Film-Based Hydrogen Sensor Using Metal-Assisted Chemical Etching with Annealed Palladium Nanoparticles

Abstract

This article reports a nanoporous silicon (Si) thinfilm-based high-performance and low-power hydrogen (H-2) sensor fabricated by metal-assisted chemical etching (MaCE). The nanoporous Si thin film treated with Pd-based MaCE showed improvement over a flat Si thin film sensor in H-2 response (Delta I/I-0 = 4.36% -> 12.4% for 0.1% H-2). Furthermore, it was verified that the combination of thermal annealing of Pd and subsequent MaCE on the Si thin film synergistically enhances the H-2 sensitivity of the sensor by 65 times as compared to the flat Si thin film sensor (Delta I/I-0 = 4.36% -> 285% for 0.1% H-2). This sensor also showed a very low operating power of 1.62 mu W. After the thermal treatment, densely packed Pd nanoparticles agglomerate due to dewetting, which results in a higher surface-to-volume ratio by well-defined etched holes, leading to an increase in sensor response.