Abstract: Due to limited resources of the natural fossil fuels, hydrogen is projected as an important energy resource for the future generation. However, the problem with the hydrogen gas is that its production, transportation, and use are very risky due to its highly explosive nature. Since hydrogen is a colorless, odorless and tasteless flammable gas, it can’t be detected by human senses. Therefore, a highly efficient hydrogen gas sensor is required to detect and monitor hydrogen concentration in case of any accidental leakage.
In general, metal oxides such as the ZnO and TiO2 are widely used as the active materials for fabricating thin film hydrogen sensors. The present lecture will address the fabrication and characterization of some ZnO and TiO2 thin-film based gas sensors using low-cost techniques such as the sol-gel and vacuum deposition methods. In this regard, the Pd/ZnO based Schottky contact based hydrogen sensors fabricated by thermal evaporation method. Various sensing parameters of the device will be presented. Then TiO2 based metal-oxide-semiconductor (MOS) and metal-semiconductor-metal (MSM) structures will be discussed for the hydrogen gas sensing-applications. Finally, the suitability of the solution processed ZnO quantum dots for hydrogen detection will be presented. Some hydrogen sensors operating at room-temperature or low-temperatures will also be considered.