Hydrogen sensing characteristics of Pd/SiO2-nanoparticles (NPs)/AlGaN metal-oxide-semiconductor (MOS) diodes

A Pd/SiO2-nanoparticles (NPs)/AlGaN metal-oxide-semiconductor (MOS) structure is used to fabricate interesting Schottky diode-type hydrogen sensors. The employment of SiO2-NPs could effectively increase the specific surface area of Pd catalytic metal and the Schottky barrier height. Good hydrogen sensing performance is obtained. Experimentally, as compared to a conventional Pd/AlGaN MS diode, a significant 34.5-fold improvement on hydrogen sensing response is obtained under an introduced 1% H2/air gas at 300 K when a 10 wt% concentration of SiO2-NPs is employed in the studied device. Yet, the increase in SiO2-NP concentration relatively deteriorates the ability to detect very low hydrogen concentration levels (≦1 ppm H2/air). In addition, the increase in SiO2-NP concentration creates a decrease and increase on response and recovery time constants of transient behaviors, respectively.