Pd/n-SiC nanofilm sensor for molecular hydrogen detection in oxygen atmosphere

We demonstrate a concept of molecular hydrogen sensor operable continuously in oxygen-rich atmosphere, using a Pd/n-SiC heterojunction structure with nanometer thickness metallization. The sensing mechanism is based on the excitation of hot electrons in the Pd nanofilm traveling ballistically over the Schottky barrier and toward the semiconductor layer to constitute a detectable electric current. If molecular oxygen is also present in the host ambient, the hydrogen sensitivity of the device increases by an order of the magnitude and the generated current acquires a stationary character. Magnitude of the stationary current is linearly proportional to the mixture pressure and to the rate of hydrogen-to-water oxidation process occurring on the Pd nanofilm surface. Hydrogen sensors of the present type can have very fast response and recovery times of only several seconds.