Gold cluster formation at the interface of a gold Langmuir-Blodgett film gold microsandwich resulting in Coulomb charging phenomena

Structural analysis of the cross section of gold/Langmuir-Blodgett (LB) pol ymer film/gold sandwich structures was performed using transmission electro n microscopy (TEM), and the obtained results were complemented by electron transport investigations of the sandwich structures. The polymer film consi sted of four to ten LB monolayers of a nonconducting polymer. TEM analysis of the sandwich cross section revealed a number of gold particles, 2-5 nm i n size, formed during the fabrication process within the LB film close to t he top electrode. Low temperature dc-transport measurements showed current- voltage (I-V) characteristics with equidistant steps that are not expected if the polymer film is thought to form a single laterally extended tunnelin g barrier between the metal electrodes. This feature can be understood, how ever, on the basis of the Coulomb blockade model applied to cluster-like me tallic inclusions acting as an island separated from both Au electrodes by tunneling barriers. (C) 1999 American Institute of Physics. [S0021-8979(99) 02806-6].