Fabrication of ultrathin metallic membranes on ceramic supports by sputter deposition

The present work focuses on the synthesis of ultrathin palladium films (< 500 nm) grown on porous ceramic supports by the sputter deposition technique. The following two parameters were found most critical to the synthesis of the gas-tight metal-ceramic composite: substrate type (surface roughness) and the deposition temperature. Fairly gas-tight Pd films with good adhesion could be coated on sol-gel derived fine pore γ-alumina supports but not on coarse α-alumina supports. Poor adhesion between the coated film and the γ-alumina support was observed for films coated at room temperature, to a thickness of 300 nm or larger. Both coating temperature (80-600°C) and substrate type affect the grain size, nitrogen gas-tightness and the adhesion of the deposited metallic films. Characterization results show that 400°C is the optimum coating temperature. XRD and SEM data on these films show that the films are fairly crystalline, with a uniform and smooth surface morphology.