Metastable Molecular Metal–Semiconductor Junctions

We demonstrate herein how to mechanically modulate the electrical properties of metastable molecular junctions, i.e., mercury−silicon junctions modified with “mobile” octadecanethiolate (C18) self-assembled monolayers (SAMs). By enlarging the mercury drop contact or changing its shape, the current density−voltage response of these molecular junctions vary remarkably from rectifying (off) to ohmic (on). More importantly, such switching behavior is reversible and reproducible when the shape of the mercury drop is changed from spherical to elliptical and vice versa (by pressing and releasing the mercury drop). Evaluation of the rectification ratio and effective barrier height of these molecular junctions enables determination of the threshold surface area of the mercury contact for the modulated electrical switching.