Fabrication of nano-gap electrodes for measuring electrical properties of organic molecules using a focused ion beam

Abstract Molecular electronics, in which a single molecule is used as an element, requires the ability to interface nanometer-sized molecules to macroscopic electronic circuits. For this end, a simple and highly reproducible method to fabricate metallic electrodes with nanometer gaps is proposed. This method consists of the patterning of a metallic mask by focused ion beam (FIB) etching and the pattern transfer to an underlying metallic electrode by dry etching. Metallic electrodes with gaps of 5–8 nm, which are much smaller than the minimum diameter of a FIB, can be reproducibly fabricated using this method. Electrical measurements of the electrodes reveal very good insulating characteristics. These electrodes are expected to be useful for electrically measuring single molecules.