Thermal stability of silver thin films on zirconia substrates

Abstract

The thermal stability of silver thin films between 100nm and 820nm 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 100nm 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.