Semimetal graphite/ZnO Schottky diodes and their use for hydrogen sensing

A method is described for the fabrication of highly rectifying Schottky contacts on n-type ZnO (O and Zn polar face) single crystals, both bare and partially covered with Pt nanoparticles, coated with mechanically deposited colloidal graphite. A layer of Pt nanoparticles deposited by in situ pulsed electrophoretic deposition from isooctane colloid solutions is inserted between the graphite and the ZnO surface serves to dissociate hydrogen molecules in hydrogen sensing elements based on the highly rectifying Schottky barriers. The sensing elements are sensitive to gas mixtures with a low hydrogen concentration down to 10 ppm and show an extremely fast response above 1000 ppm.