Hydrogen sensing properties of a novel GaN/AlGaN Schottky diode decorated with palladium nanoparticles and a platinum thin film

Abstract The interesting bimetallic catalysts incorporating a GaN/AlGaN heterostructure are used herein to produce a new Schottky diode-type hydrogen sensor. This bimetallic-catalytic structure includes palladium (Pd) nanoparticles (NP) and a platinum (Pt) thin film. Due to the increased surface area/volume (SA/V) ratio and spill-over effect of Pd NPs and the catalytic reactivity of the Pt thin film, the result is prominent hydrogen sensing performance. In our experiment, the studied Pd NP/Pt thin film/GaN/AlGaN-based sensor exhibits a very high sensing response of 2.35 × 107 (under 1% H2/air gas at 300 K) with short response and recovery times of 18 s and 12 s. In addition, an extremely low detecting level (≤ 1 ppm H2/air) is acquired. The studied device shows the hydrogen sensing ability among widespread range for operating temperature (300-473 K) and hydrogen concentration (1 ppm - 1% H2/air). The humidity effect on the sensing response is studied in this work. Moreover, the related hydrogen sensing mechanism and a theoretical analysis used to study the hydrogen coverage at the Pt/GaN interface are included in this work. For the Internet of Things (IoT) application, a modified Kalman algorithm is used to substantially reduce the redundant data. More than 1040 (71.9%) data points of the original data under 100 ppm H2/air gas at 300 K are removed. Furthermore, the related mean recovery error (MRE) is only 5.75%.