Electric-field penetration into metals: Consequences for high-dielectric-constant capacitors

A consequence of the finite electronic screening length in metals is that e lectric fields penetrate short distances into the metal surface. Using a si mple, semiclassical model of an idealized capacitor, we estimate the capaci tance correction due to the distribution of displacement charge in the meta l electrodes. We compare our result with experimental data from thin-film h igh-dielectric-constant capacitors, which are currently leading contenders for use in future high-density memory applications. This intrinsic mechanis m contributes to the universally-seen decrease in measured dielectric const ant with capacitor film thickness.