Correlations between mechanical stress, electrical conductivity and nanostructure in Al films on a polymer substrate

The relation between mechanical stress, electrical resistivity and film nanostructure is investigated here for 100 nm thick aluminum films deposited on micrometer-thick polysulfone. It is observed that film electrical resistivity increases significantly before mechanical failure occurs, because of the formation of micro-cracks on the film surface. The applied tensile stress also influences the film nanostructure in an irreversible manner, causing plastic rearrangement of the film grains well before macroscopic failure occurs, which suggests stress-assisted grain growth at the nanostructural level.