Tunneling through Fatty Acid Salt Monolayers

Abstract

Sandwiches of monolayers of Cd salts of fatty acids CH₃(CH₂)_n−2COOH of different chain lengths between metal electrodes show the exponential decrease of conductivity vs thickness predicted by the tunnel theory. The electron work function from metal to dielectric is obtained. The current‐on‐voltage dependence is predicted and it is found to be in good agreement with experiment. The effects of changing the electrode material are quantitatively predicted from the differences between the vacuum work functions of the metals used (Hg, Al, Pb, and Au). The good agreement between theory and experiment can be taken as an extremely sensitive test for the uniformity of the monolayers obtained by the monolayer assembling technique used in this investigation.