Size-dependent electrical behavior of spatially inhomogeneous barrier height regions on silicon

A series of ordered, periodic arrays of low barrier height n-Si/Ni nanometer-scale contacts interspersed among high barrier height n-Si/liquid contacts were prepared by evaporating Ni through bilayers of close-packed latex spheres deposited on n-Si. By varying the diameter of the spheres from 174 to 1530 nm, geometrically self-similar Si/Ni structures were produced having triangular Si/Ni features ranging from approximately 100 to 800 nm on a side. The resulting Si surfaces were used as electrodes in methanolic electrochemical cells containing LiClO4 and 1,1′-dimethylferrocene+/o. The dark current density–voltage properties of the resulting mixed barrier height contacts were strongly dependent on the size of the low barrier height contact regions even though the fraction of the Si surface covered by Ni remained constant.