Structural, morphological and hydrogen sensing studies on pulsed laser deposited nanostructured palladium thin films

We have systematically investigated hydrogen sensing properties of pulsed laser deposited palladium thin films with reference to their crystallinity, surface morphology and film thickness. Thin films were deposited on clean quartz substrates at varying growth parameters. Structural and surface morphological characterizations have been carried out using X-ray diffraction, scanning electron microscopy and atomic force microscopy. Thin films with nanostructured surface morphology were achieved. Electrical resistance measurements, carried out in situ, by a two-probe technique in a chamber with a provision to introduce a known concentration of hydrogen gas and air, showed saturation on exposure to hydrogen gas. The change in electrical resistance due to hydrogen loading is found to be reversible. The sensor response time is typically 10-20 s. The Pd films are stable after several cycles of hydrogenation and dehydrogenation.