Hydrogen sensors based on Ni/SiO2/Si MOS capacitors

A novel hydrogen sensor based on Ni/SiO2/Si MOS capacitors were fabricated and characterized at hydrogen concentrations ranging from 50 to 1000 ppm at an operating temperature of 140 °C. The highest response occurs at the same bias voltage (−0.4 V) for all the concentration levels measured and is about 18% at 50 ppm. The response/recovery transients of the Ni-based sensors are similar to those of the Pd-based hydrogen sensors. A Langmuir isotherm model is adapted to explain the observed phenomena, which is in agreement with our experimental results.