Unconventional thickness dependence of electrical resistivity of silver film electrodes in substoichiometric oxidation states

The scaling down of metallic electrodes into ultrathin film geometries presents significant challenges in precisely controlling electrical resistivity. This difficulty stems from the rapid variation in resistivity with thickness, particularly near the percolation threshold. Currently, our understanding of the prediction of thickness-dependent resistivity in metallic film electrodes in volatile substoichiometric oxide (suboxide) states is limited. This study offers experimental and numerical evidence demonstrating a marked resistivity fluctuation spanning four to five orders of magnitude during the initial growth stages of suboxidized Ag film electrodes. These stages range from cluster coalescence to reaching the percolation threshold. The unusual resistivity change is attributed to the variation in suboxidation states with thickness, as well as the outward migration of interstitial O ions. These findings offer a crucial framework for controlling the electrical properties of thin metallic oxide films in extreme suboxidation states, extending beyond the conventional understanding applicable to thermodynamically stable metallic oxide phases.