An experimental characterization and theoretical analysis of MOS-based Schottky diode hydrogen sensors

In past years, compact hydrogen sensing device research has been focused on applications in the aerospace industry. These devices however, may be useful in medical and telecommunication applications. Our work focuses on understanding MOS based hydrogen sensing Schottky diode devices fabricated at Case Western Reserve University for an application involving sensing hydrogen levels in sealed microwave telecommunication modules. Here, we explain the behavior of these devices over a wide range of hydrogen concentration using a model based on the standard semiconductor diode theory and hydrogen diffusion theory. The model assumes that the Schottky barrier of the MOS diode varies with the concentration of hydrogen. Data from tests on devices with hydrogen concentrations between 25 ppm and 588 ppm at temperatures from 20{dollar}spcirc{dollar}C to 80{dollar}spcirc{dollar}C were found to be in excellent agreement with the model.