As promising building blocks for molecular electronics, organic molecules have attracted intense research interest. Metal-molecule-metal junctions are often used as testbeds for studying organic molecules' charge transport properties. In this article, fabrication methods, nanoscalability and addressability of these junctions are reviewed. Fabrication approaches are classified into soft contact, scanning probe microscopy, against-nanowire, crossed-wire, shadow angle evaporation and nanopore

more »

... ions. The effects of preparation method on the junction charge transport properties are systematically discussed. In general, the scanning tunneling microscopy technique is suitable for fast screening of molecular conductance, but cannot address junction that limits their in-situ temperature-dependent characterizations. The nanopore junction guarantees good control over the device size and the intrinsic contact stability, however, the nature of the electrode-molecule interface is not well understood. Shadow angle evaporation and soft contact techniques can effectively reduce the possibility of device short circuiting; however, the electrode dimensions limit potential applications. The against-nanowire method provides an easy way to fabricate addressable junctions, and if combined with the crossed-wire procedure may have potential for fabrication and three-dimensional integration of molecular junctions.