Nanocrystalline Palladium Thin Films for Hydrogen Sensor Application

Palladium nanocrystalline films on SiO2/Si were prepared by DC-magnetron sputtering and utilized, as-grown, to detect hydrogen at room temperature. The gas sensing mechanism for the as-deposited Pd based resistive sensors is postulated as a combination of chemical and electronic sensitization mechanism influenced by the size of the Pd particles in the film. Performance of the H-2 sensor (sensitivity and response) has been correlated to the deposition pressure and grain size of the Pd film. The morphology and crystallinity of the films were validated using Atomic Force Microscope (AFM) and X-Ray Diffraction (XRD), respectively. Real time hydrogen sensing using the as-deposited Pd nanocrystalline films circumvents catalytic poisoning effects while enabling a defect-free (PdO or PdxSiy) platform for cross-sensitivity studies.