Thermal stability of silver thin films on zirconia substrates

The thermal stability of silver thin films between 100 nm and 820 nm thick deposited onto single crystal yttria-stabilised zirconia (YSZ) substrates by evaporation was investigated by annealing the films between 250 °C and 550 °C for different durations. Films approximately 100 nm thick were thermally unstable at temperatures as low as 250 °C. A dewetting process occurred in which grain boundaries ruptured, to uncover the substrate and reduce the overall energy of the system, by a combination of grain boundary grooving at the outer surface and void growth at the Ag-YSZ interface. The surface self diffusion coefficient of Ag was determined from the kinetics of the process to be 2.6 ± 0.3 × 10− 5 cm2s− 1 at 500 °C. The resulting silver morphology ranged from 'self-organised' interconnected silver network structures to completely isolated silver islands. A structure predominance map of the rearrangement process is presented.