Dependency of the tunneling decay coefficient in molecular tunneling junctions on the topography of the bottom electrodes

Abstract

A controversy in molecular electronics is the unexplained large spread in values of the tunneling decay coefficient β in tunneling junctions with self-assembled monolayers of n-alkanethiolates (SC(n)). We show control of the β value over the range 0.4-1.0 n(C)(-1) in junctions by changing the topography of the bottom electrodes that support the SAMs. Very low β values (0.4-0.5 n(C)(-1)) are obtained for rough surfaces with large areas of exposed grain boundaries, while β=1.0 n(C)(-1) for smooth surfaces with small areas of exposed grain boundaries.

Keywords: bottom electrodes; charge transport; molecular electronics; self-assembled monolayers; tunneling decay constant.