Hydrogen gas detection using MOS capacitor sensor based on palladium nanoparticles-gate

In this study a palladium nanoparticles-gate MOS capacitor hydrogen sensor with Pd/SiO2/Si structure has been fabricated. The palladium nanoparticles by chemical method are synthesized and then characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and UV-VIS spectrum. Also, the preferred orientation and grain size of the palladium nanoparticles have been studied. Hydrogen absorption and desorption of the palladium nanoparticles at the low and high pressure and as function of time have been investigated. The sensing mechanism of the hydrogen detection by MOS capacitor sensor has been explained and theoretical and experimental results have been compared. At 287 K, compared to another Pd MOS capacitor hydrogen sensor and ultrathin Pd MOS capacitor, the palladium nanoparticles gate MOS capacitor showed much faster response and recovery speed. The time interval for reaching to 95% of the steady state signal magnitude (t(95%)) for 1% and 2% hydrogen in nitrogen were 2 s and 1.5 s respectively. The time interval for recovery transients from 95% to 10% of steady state signal magnitude (t(10%)) for 1% and 2% hydrogen in nitrogen were 10 s and 11 s respectively. The presented sensor illustrates a designing of hydrogen detectors with very fast response and recovery speed.